🕷️ Crawler Inspector

URL Lookup

Direct Parameter Lookup

Raw Queries and Responses

1. Shard Calculation

Query:

Response:

Calculated Shard: 152 (from laksa122)

2. Crawled Status Check

Query:

curl -X POST \
  'http://laksa152.int.ahrefs:8124/' \
  -H 'Content-Type: text/plain' \
  -H 'X-ClickHouse-Database: crawler3' \
  -H 'Authorization: Basic YXBpOg==' \
  -d 'SELECT getAhrefsURLFromUnparsed(src_unparsed) AS found_url, ifNull(toUnixTimestamp(download_stamp), 0) AS crawl_time, ifNull(toUnixTimestamp(props_url_first_seen), 0) AS first_indexed_time, download_http_code AS http_code, src_unparsed AS src_unparsed, src_root_hash AS src_root_hash, history_drop_reason AS history_drop_reason, meta_title AS meta_title, meta_descriptions AS meta_descriptions, attrs_boilerpipe_text AS attrs_boilerpipe_text, attrs_markdown AS attrs_markdown, attrs_readable_markdown AS attrs_readable_markdown, meta_canonical AS meta_canonical FROM crawler3.page_info_local FINAL PREWHERE (src_root_hash, src_unparsed) IN ((getAhrefsRootHashFromUnparsed(getAhrefsUnparsedNoserviceFromURL(\'https://en.wikipedia.org/wiki/Well\')), getAhrefsUnparsedNoserviceFromURL(\'https://en.wikipedia.org/wiki/Well\'))) FORMAT JSONEachRow'

Response:

{"found_url":"https:\/\/en.wikipedia.org\/wiki\/Well","crawl_time":1775939902,"first_indexed_time":1434636077,"http_code":200,"src_unparsed":"org,wikipedia!en,\/wiki\/Well s443","src_root_hash":"17790707453426894952","history_drop_reason":null,"meta_title":"Well - Wikipedia","meta_descriptions":[],"attrs_boilerpipe_text":"\"Village pump\" redirects here. For the set of Wikipedia discussion pages, see\nWikipedia:Village pump\n.\nA dug well in a village in\nFaryab Province\n,\nAfghanistan\nThe difference between a well and a\ncistern\nis in the source of the water: a cistern collects\nrainwater\nwhereas a well draws from\ngroundwater\n.\nA\nwell\nis an excavation or structure created on the earth by\ndigging\n, driving, or\ndrilling\nto access\nliquid\nresources, usually\nwater\n. The oldest and most common kind of well is a water well, to access\ngroundwater\nin underground\naquifers\n. The well water is drawn up by a\npump\n, or using containers, such as\nbuckets\nthat are raised mechanically or by hand. Water can also be\ninjected back into the aquifer\nthrough the well. Wells were first constructed at least eight thousand years ago and historically vary in construction from a sediment of a dry watercourse to the\nqanats\nof Iran, and the\nstepwells\nand\nsakiehs\nof India. Placing a lining in the well shaft helps create stability, and linings of wood or\nwickerwork\ndate back at least as far as the\nIron Age\n.\nWells have traditionally been sunk by hand digging, as is still the case in rural areas of the developing world. These wells are inexpensive and low-tech as they use mostly manual labour, and the structure can be lined with\nbrick\nor stone as the excavation proceeds. A more modern method called\ncaissoning\nuses pre-cast reinforced concrete well rings that are lowered into the hole. Driven wells can be created in unconsolidated material with a well hole structure, which consists of a hardened drive point and a screen of perforated pipe, after which a pump is installed to collect the water. Deeper wells can be excavated by hand drilling methods or machine drilling, using a\nbit\nin a\nborehole\n. Drilled wells are usually cased with a factory-made pipe composed of steel or plastic. Drilled wells can access water at much greater depths than dug wells.\nTwo broad classes of well are shallow or unconfined wells completed within the uppermost saturated\naquifer\nat that location, and deep or confined wells, sunk through an impermeable stratum into an aquifer beneath. A collector well can be constructed adjacent to a freshwater lake or stream with water percolating through the intervening material. The site of a well can be selected by a\nhydrogeologist\n, or groundwater surveyor. Water may be pumped or hand drawn. Impurities from the surface can easily reach shallow sources and contamination of the supply by pathogens or chemical contaminants needs to be avoided. Well water typically contains more minerals in solution than surface water and may require\ntreatment\nbefore being potable.\nSoil salination\ncan occur as the water table falls and the surrounding soil begins to dry out. Another environmental problem is the potential for\nmethane\nto seep into the water.\nCamel drawing water from a well,\nDjerba\nisland, Tunisia, 1960\nVery early\nNeolithic\nwells are known from the\nEastern Mediterranean\n.\n[\n1\n]\nThe oldest reliably dated well is from the\npre-pottery neolithic\n(PPN) site of Kissonerga-Mylouthkia on\nCyprus\n. At around 8400 BC a shaft (well 116) of circular diameter was driven through limestone to reach an\naquifer\nat a depth of 8 metres (26 ft). Well 2070 from Kissonerga-Mylouthkia, dating to the late PPN, reaches a depth of 13 metres (43 ft). Other slightly younger wells are known from this site and from neighbouring Parekklisha-Shillourokambos. A first stone lined\n[\n2\n]\nwell of 5.5 metres (18 ft) depth is documented from a drowned final PPN (c. 7000 BC) site at\n'Atlit-Yam\noff the coast near modern\nHaifa\nin\nIsrael\n.\nNeolithic\nLinear Pottery culture\nwell, 5300 BC,\nErkelenz\n, Germany\nWood-lined wells are known from the early Neolithic\nLinear Pottery culture\n, for example in Ostrov, Czech Republic, dated 5265 BC,\n[\n3\n]\nKückhoven (an outlying centre of\nErkelenz\n), dated 5300 BC,\n[\n4\n]\nand\nEythra\nin Schletz (an outlying centre of\nAsparn an der Zaya\n) in\nAustria\n, dated 5200 BC.\n[\n5\n]\nThe Neolithic Chinese discovered and made extensive use of deep drilled groundwater for drinking.\n[\ncitation needed\n]\nThe Chinese text\nThe Book of Changes\n, originally a divination text of the Western Zhou dynasty (1046 -771 BC), contains an entry describing how the ancient Chinese maintained their wells and protected their sources of water.\n[\n6\n]\nA well excavated at the\nHemedu\nexcavation site was believed to have been built during the neolithic era.\n[\n7\n]\nThe well was cased by four rows of logs with a square frame attached to them at the top of the well. 60 additional tile wells southwest of Beijing are also believed to have been built around 600 BC for drinking and irrigation.\n[\n7\n]\n[\n8\n]\nA Chinese ceramic model of a well with a water\npulley\nsystem, excavated from a tomb of the\nHan dynasty\n(202 BC – 220 AD) period\nIn\nEgypt\n,\nshadoofs\nand\nsakias\nare used.\n[\n9\n]\n[\n10\n]\nThe sakia is much more efficient, as it can bring up water from a depth of 10 metres (versus the 3 metres of the shadoof). The sakia is the Egyptian version of the\nnoria\n. Some of the world's oldest known wells, located in Cyprus, date to 7000–8,500 BC.\n[\n11\n]\nTwo wells from the Neolithic period, around 6500 BC, have been discovered in Israel. One is in Atlit, on the northern coast of Israel, and the other is in the Jezreel Valley.\n[\n12\n]\nWells for other purposes came along much later, historically. The first recorded\nsalt well\nwas dug in the Sichuan province of China around 2,250 years ago. This was the first time that ancient water well technology was applied successfully for the exploitation of salt, and marked the beginning of Sichuan's salt drilling industry.\n[\n6\n]\nThe earliest known\noil wells\nwere also drilled in China, in 347 CE. These wells had depths of up to about 240 metres (790 ft) and were drilled using\nbits\nattached to\nbamboo\npoles.\n[\n13\n]\nThe oil was burned to evaporate\nbrine\nand produce\nsalt\n. By the 10th century, extensive\nbamboo\npipelines connected oil wells with salt springs. The ancient records of China and\nJapan\nare said to contain many allusions to the use of natural gas for lighting and heating. Petroleum was known as\nBurning water\nin Japan in the 7th century.\n[\n14\n]\nWater well near\nSimaisma\n, eastern Qatar\nLeather bucket used for the water well\nWell, Historical Village, Bhaini Sahib,\nLudhiana\n,\nPunjab\n, India\nView into a hand-dug well cased with concrete rings.\nOuelessebougou\n, Mali.\nA dug well in a village in\nKerala\n, India\nWell with a flower bag-shaped wall and podium\nUntil recent centuries, all artificial wells were\npumpless\nhand-dug wells of varying degrees of sophistication, and they remain a very important source of\npotable water\nin some rural developing areas, where they are routinely dug and used today. Their indispensability has produced a number of literary references, literal and figurative, including the reference to the incident of\nJesus\nmeeting a woman at\nJacob\n's well (\nJohn\n4:6) in the Bible and the \"\nDing Dong Bell\n\"\nnursery rhyme\nabout a cat in a well.\nHand-dug wells are excavations with diameters large enough to accommodate one or more people with shovels digging down to below the\nwater table\n. The excavation is braced horizontally to avoid landslide or erosion endangering the people digging. They can be lined with stone or brick; extending this lining upwards above the ground surface to form a wall around the well serves to reduce both contamination and accidental falls into the well.\nA more modern method called\ncaissoning\nuses reinforced concrete or plain concrete pre-cast well rings that are lowered into the hole. A well-digging team digs under a cutting ring and the well column slowly sinks into the\naquifer\n, whilst protecting the team from collapse of the well\nbore\n.\nHand-dug wells are inexpensive and low tech (compared to drilling) and they use mostly manual labour to access groundwater in rural locations of developing countries.  They may be built with a high degree of community participation, or by local entrepreneurs who specialize in hand-dug wells. They have been successfully excavated to 60 metres (200 ft). They have low operational and maintenance costs, in part because water can be extracted by hand, without a pump. The water often comes from an aquifer or groundwater, and can be easily deepened, which may be necessary if the ground water level drops, by telescoping the lining further down into the aquifer. The yield of existing hand dug wells may be improved by deepening or introducing vertical tunnels or perforated pipes.\nDrawbacks to hand-dug wells are numerous. It can be impractical to hand dig wells in areas where hard rock is present, and they can be time-consuming to dig and line even in favourable areas. Because they exploit shallow aquifers, the well may be susceptible to yield fluctuations and possible contamination from surface water, including sewage. Hand dug well construction generally requires the use of a well trained construction team, and the capital investment for equipment such as concrete ring moulds, heavy lifting equipment, well shaft formwork, motorized de-watering pumps, and fuel can be large for people in developing countries. Construction of hand dug wells can be dangerous due to collapse of the well bore, falling objects and asphyxiation, including from dewatering pump exhaust fumes.\nThe\nWoodingdean Water Well\n, hand-dug between 1858 and 1862, is the deepest hand-dug well at 392 metres (1,285 ft).\n[\n15\n]\nThe\nBig Well\nin\nGreensburg, Kansas\n, is billed as the world's largest hand-dug well, at 109 feet (33 m) deep and 32 feet (9.8 m) in diameter. However, the\nWell of Joseph\nin the\nCairo Citadel\nat 280 feet (85 m) deep and the\nPozzo di San Patrizio\n(St. Patrick's Well) built in 1527 in\nOrvieto, Italy\n, at 61 metres (200 ft) deep by 13 metres (43 ft) wide\n[\n16\n]\nare both larger by volume.\nDriven wells may be very simply created in unconsolidated material with a\nwell hole structure\n, which consists of a hardened drive point and a screen (perforated pipe). The point is simply hammered into the ground, usually with a tripod and\ndriver\n, with pipe sections added as needed. A driver is a weighted pipe that slides over the pipe being driven and is repeatedly dropped on it. When\ngroundwater\nis encountered, the well is washed of sediment and a pump installed.\n[\n17\n]\nDrilled wells are constructed using various types of drilling machines, such as top-head rotary, table rotary, or cable tool, which all use drilling stems that rotate to cut into the formation, thus the term \"drilling.\"\nDrilled wells can be excavated by simple hand drilling methods (augering, sludging, jetting, driving, hand percussion) or machine drilling (auger, rotary, percussion, down the hole hammer). Deep rock rotary drilling method is most common. Rotary can be used in 90% of formation types (consolidated).\nDrilled wells can get water from a much deeper level than dug wells can − often down to several hundred metres.\n[\n18\n]\nDrilled wells with electric pumps are used throughout the world, typically in rural or sparsely populated areas, though many urban areas are supplied partly by municipal wells. Most shallow well drilling machines are mounted on large trucks, trailers, or tracked vehicle carriages. Water wells typically range from 3 to 18 metres (10–60 ft) deep, but in some areas it can go deeper than 900 metres (3,000 ft).\n[\ncitation needed\n]\nCable tool\nwater well drilling rig in\nKimball, West Virginia\nIsraeli geologist\nLeo Picard\n(white shirt) inspects a drilled water well outside the depopulated Palestinian village of\nBayt Naqquba\nRotary drilling machines use a segmented steel drilling string, typically made up of 3m (10ft), 6 m (20 ft) to 8m (26ft) sections of steel tubing that are threaded together, with a\nbit\nor other drilling device at the bottom end.  Some rotary drilling machines are designed to install (by driving or drilling) a steel casing into the well in conjunction with the drilling of the actual bore hole. Air and\/or water is used as a circulation fluid to displace cuttings and cool bits during the drilling. Another form of rotary-style drilling, termed\nmud rotary\n, makes use of a specially made mud, or drilling fluid, which is constantly being altered during the drill so that it can consistently create enough hydraulic pressure to hold the side walls of the bore hole open, regardless of the presence of a casing in the well. Typically, boreholes drilled into solid rock are not cased until after the drilling process is completed, regardless of the machinery used.\nThe oldest form of drilling machinery is the\ncable tool\n, still used today. Specifically designed to raise and lower a bit into the bore hole, the\nspudding\nof the drill causes the bit to be raised and dropped onto the bottom of the hole, and the design of the cable causes the bit to twist at approximately\n1\n⁄\n4\nrevolution per drop, thereby creating a drilling action. Unlike rotary drilling, cable tool drilling requires the drilling action to be stopped so that the bore hole can be bailed or emptied of drilled cuttings. Cable tool drilling rigs are rare as they tend to be 10x slower to drill through materials compared to similar diameter rotary air or rotary mud equipped rigs.\nDrilled wells are usually cased with a factory-made pipe, typically\nsteel\n(in air rotary or cable tool drilling) or\nplastic\n\/\nPVC\n(in mud rotary wells, also present in wells drilled into solid rock). The casing is constructed by welding, either chemically or thermally, segments of casing together. If the casing is installed during the drilling, most drills will drive the casing into the ground as the bore hole advances, while some newer machines will actually allow for the casing to be rotated and drilled into the formation in a similar manner as the bit advancing just below.  PVC or plastic is typically solvent welded and then lowered into the drilled well, vertically stacked with their ends nested and either glued or splined together. The sections of casing are usually 6 metres (20 ft) or more in length, and 4 to 12 in (10 to 30 cm) in diameter, depending on the intended use of the well and local groundwater conditions.\nSurface contamination of wells in the United States is typically controlled by the use of a\nsurface seal\n. A large hole is drilled to a predetermined depth or to a confining formation (clay or bedrock, for example), and then a smaller hole for the well is completed from that point forward. The well is typically cased from the surface down into the smaller hole with a casing that is the same diameter as that hole. The annular space between the large bore hole and the smaller casing is filled with\nbentonite clay\n, concrete, or other sealant material. This creates an impermeable seal from the surface to the next confining layer that keeps contaminants from traveling down the outer sidewalls of the casing or borehole and into the\naquifer\n. In addition, wells are typically capped with either an engineered well cap or seal that vents air through a screen into the well, but keeps insects, small animals, and unauthorized persons from accessing the well.\nAt the bottom of wells, based on formation, a screening device, filter pack, slotted casing, or open bore hole is left to allow the flow of water into the well. Constructed screens are typically used in unconsolidated formations (sands, gravels, etc.), allowing water and a percentage of the formation to pass through the screen. Allowing some material to pass through creates a large area filter out of the rest of the formation, as the amount of material present to pass into the well slowly decreases and is removed from the well. Rock wells are typically cased with a PVC liner\/casing and screen or slotted casing at the bottom, this is mostly present just to keep rocks from entering the pump assembly. Some wells use a\nfilter pack\nmethod, where an undersized screen or slotted casing is placed inside the well and a filter medium is packed around the screen, between the screen and the borehole or casing. This allows the water to be filtered of unwanted materials before entering the well and pumping zone.\nAn automated water well system powered by a jet-pump\nAn automated water well system powered by a submersible pump\nA water well system with a cistern\nA water well system with a pressurized cistern\nA section of a stainless steel screen well\nWater well types\nThere are two broad classes of drilled-well types, based on the type of\naquifer\nthe well is in:\nShallow\nor\nunconfined wells\nare completed in the uppermost saturated aquifer at that location (the upper unconfined aquifer).\n[\ncitation needed\n]\nDeep\nor\nconfined wells\nare sunk through an impermeable stratum into an aquifer that is sandwiched between two impermeable strata (aquitards or aquicludes).  The majority of deep aquifers are classified as artesian because the hydraulic head in a confined well is higher than the level of the top of the aquifer. If the hydraulic head in a confined well is higher than the land surface it is a \"flowing\"\nartesian well\n(named after\nArtois\nin\nFrance\n).\n[\n19\n]\nAn old-fashioned water well in the countryside of\nUtajärvi\n,\nFinland\nA special type of water well may be constructed adjacent to freshwater lakes or streams. Commonly called a collector well but sometimes referred to by the trade name Ranney well or\nRanney collector\n, this type of well involves sinking a caisson vertically below the top of the aquifer and then advancing lateral collectors out of the caisson and beneath the surface water body. Pumping from within the caisson induces infiltration of water from the surface water body into the aquifer, where it is collected by the collector well laterals and conveyed into the caisson where it can be pumped to the ground surface.\n[\ncitation needed\n]\nTwo additional broad classes of well types may be distinguished, based on the use of the well:\nproduction\nor\npumping wells\n, are large diameter (greater than 15 cm in diameter) cased (metal, plastic, or concrete) water wells,  constructed for extracting water from the aquifer by a\npump\n(if the well is not\nartesian\n).\n[\ncitation needed\n]\nSchematic diagram of a groundwater monitoring well\nmonitoring wells\nor\npiezometers\n, are often smaller diameter wells used to monitor the hydraulic head or sample the groundwater for chemical constituents. Piezometers are monitoring wells completed over a very short section of aquifer. Monitoring wells can also be completed at multiple levels, allowing discrete samples or measurements to be made at different vertical elevations at the same map location.\n[\n20\n]\nA water well constructed for pumping groundwater can be used passively as a monitoring well and a small diameter well can be pumped, but this distinction by use is common.\n[\ncitation needed\n]\nBefore excavation, information about the geology, water table depth, seasonal fluctuations, recharge area and rate should be found if possible. This work can be done by a\nhydrogeologist\n, or a groundwater surveyor using a variety of tools including electro-seismic surveying,\n[\n21\n]\nany available information from nearby wells, geologic maps, and sometimes\ngeophysical imaging\n.  These professionals provide advice that is almost as accurate a driller who has experience and knowledge of nearby wells\/bores and the most suitable drilling technique based on the expected target depth.\nWaterborne diseases\ncan be spread via a well which is contaminated with fecal pathogens from\npit latrines\n.\nMan cleaning a well in\nYaoundé\n,\nCameroon\nHand pump to pump water from a well in a village near Chennai in India, where the well water might be polluted by nearby\npit latrines\n.\nShallow pumping wells can often supply\ndrinking water\nat a very low cost. However, impurities from the surface easily reach shallow sources, which leads to a greater risk of contamination for these wells compared to deeper wells. Contaminated wells can lead to the spread of various\nwaterborne diseases\n. Dug and driven wells are relatively easy to contaminate; for instance, most dug wells are unreliable in the majority of the United States.\n[\n22\n]\nSome research has found that, in cold regions, changes in river flow and flooding caused by extreme rainfall or snowmelt can degrade well water quality.\n[\n23\n]\nMost of the\nbacteria\n,\nviruses\n,\nparasites\n, and\nfungi\nthat contaminate well water comes from\nfecal material\nfrom humans and other animals. Common bacterial contaminants include\nE. coli\n,\nSalmonella\n,\nShigella\n, and\nCampylobacter jejuni\n. Common viral contaminants include\nnorovirus\n,\nsapovirus\n,\nrotavirus\n,\nenteroviruses\n, and\nhepatitis A\nand\nE\n. Parasites include\nGiardia lamblia\n,\nCryptosporidium\n,\nCyclospora cayetanensis\n, and\nmicrosporidia\n.\n[\n22\n]\nChemical contamination\n[\nedit\n]\nChemical contamination is a common problem with groundwater.\n[\n24\n]\nNitrates\nfrom\nsewage\n,\nsewage sludge\nor\nfertilizer\nare a particular problem for babies and young children. Pollutant chemicals include\npesticides\nand\nvolatile organic compounds\nfrom\ngasoline\n,\ndry-cleaning\n, the fuel additive\nmethyl tert-butyl ether\n(MTBE), and\nperchlorate\nfrom rocket fuel, airbag inflators, and other artificial and natural sources.\n[\ncitation needed\n]\nSeveral minerals are also contaminants, including\nlead\nleached from brass fittings or old lead pipes,\nchromium VI\nfrom electroplating and other sources, naturally occurring\narsenic\n,\nradon\n, and\nuranium\n—all of which can cause cancer—and naturally occurring\nfluoride\n, which is desirable in low quantities to prevent\ntooth decay\n, but can cause\ndental fluorosis\nin higher concentrations.\n[\n22\n]\nSome chemicals are commonly present in water wells at levels that are not toxic, but can cause other problems.\nCalcium\nand\nmagnesium\ncause what is known as\nhard water\n, which can precipitate and clog pipes or burn out water heaters.\nIron\nand\nmanganese\ncan appear as dark flecks that stain clothing and plumbing, and can promote the growth of\niron and manganese bacteria\nthat can form slimy black colonies that clog pipes.\n[\n22\n]\nThe quality of the well water can be significantly increased by lining the well, sealing the well head, fitting a self-priming hand pump, constructing an apron, ensuring the area is kept clean and free from stagnant water and animals, moving sources of contamination (\npit latrines\n, garbage pits,\non-site sewer systems\n) and carrying out hygiene education. The well should be cleaned with 1% chlorine solution after construction and periodically every 6 months.\n[\ncitation needed\n]\nWell holes should be covered to prevent loose debris, animals, animal excrement, and wind-blown foreign matter from falling into the hole and decomposing. The cover should be able to be in place at all times, including when drawing water from the well. A suspended roof over an open hole helps to some degree, but ideally the cover should be tight fitting and fully enclosing, with only a screened air vent.\n[\ncitation needed\n]\nMinimum distances and soil percolation requirements between sewage disposal sites and water wells need to be observed. Rules regarding the design and installation of private and municipal septic systems take all these factors into account so that nearby drinking water sources are protected.\nEducation of the general population in society also plays an important role in protecting drinking water.\n[\ncitation needed\n]\nCleanup of\ncontaminated groundwater\ntends to be very costly. Effective\nremediation of groundwater\nis generally very difficult. Contamination of groundwater from surface and subsurface sources can usually be dramatically reduced by correctly centering the casing during construction and filling the casing\nannulus\nwith an appropriate sealing material. The sealing material (grout) should be placed from immediately above the production zone back to surface, because, in the absence of a correctly constructed casing seal, contaminated fluid can travel into the well through the casing annulus. Centering devices are important (usually one per length of casing or at maximum intervals of 9 m) to ensure that the grouted annular space is of even thickness.\n[\ncitation needed\n]\nUpon the construction of a new test well, it is considered best practice to invest in a complete battery of chemical and biological tests on the well water in question.  Point-of-use treatment is available for individual properties and treatment plants are often constructed for municipal water supplies that suffer from contamination.  Most of these treatment methods involve the\nfiltration\nof the contaminants of concern, and additional protection may be garnered by installing well-casing screens only at depths where contamination is not present.\n[\ncitation needed\n]\nWellwater for personal use is often filtered with\nreverse osmosis\nwater processors; this process can remove very small particles.  A simple, effective way of killing microorganisms is to bring the water to a full boil for one to three minutes, depending on location. A household well contaminated by microorganisms can initially be treated by shock chlorination using bleach, generating concentrations hundreds of times greater than found in community water systems; however, this will not fix any structural problems that led to the contamination and generally requires some expertise and testing for effective application.\n[\n22\n]\nAfter the filtration process, it is common to implement an\nultraviolet\n(UV) system to kill pathogens in the water. UV light affects the DNA of the pathogen by UV-C photons breaking through the cell wall. UV disinfection has been gaining popularity in the past decades as it is a chemical-free method of water treatment.\n[\n25\n]\nEnvironmental problems\n[\nedit\n]\nA risk with the placement of water wells is\nsoil salination\nwhich occurs when the water table of the soil begins to drop and salt begins to accumulate as the soil begins to dry out.\n[\n26\n]\nAnother environmental problem that is very prevalent in water well drilling is the potential for methane to seep through.\nThe potential for soil salination is a large risk when choosing the placement of water wells. Soil salination is caused when the water table of the soil drops over time and salt begins to accumulate. In turn, the increased amount of salt begins to dry the soil out. The increased level of salt in the soil can result in the degradation of soil and can be very harmful to vegetation.\n[\ncitation needed\n]\nMethane\n, an asphyxiant, is a chemical compound that is the main component of natural gas. When methane is introduced into a confined space, it displaces oxygen, reducing oxygen concentration to a level low enough to pose a threat to humans and other aerobic organisms but still high enough for a risk of\nspontaneous\nor externally caused explosion.  This potential for explosion is what poses such a danger in regards to the drilling and placement of water wells.\n[\ncitation needed\n]\nLow levels of methane in drinking water are not considered toxic. When methane seeps into a water supply, it is commonly referred to as \"methane migration\". This can be caused by old natural gas wells near water well systems becoming abandoned and no longer monitored.\n[\ncitation needed\n]\nLately,\n[\nwhen?\n]\nhowever, the described wells\/pumps are no longer very efficient and can be replaced by either\nhandpumps\nor\ntreadle pumps\n. Another alternative is the use of self-dug wells, electrical deep-well pumps (for higher depths).\nAppropriate technology\norganizations as\nPractical Action\nare now\n[\nwhen?\n]\nsupplying information on how to build\/set-up (\nDIY\n) handpumps and\ntreadle pumps\nin practice.\n[\n27\n]\n[\n28\n]\nPFAS\/PFOS Fire fighting foam\n[\nedit\n]\nPer- and polyfluoroalkyl substances\n(\nPFAS\nor\nPFASs\n) are a group of synthetic\norganofluorine\nchemical compounds\nthat have multiple\nfluorine\natoms attached to an\nalkyl\nchain.  PFAS are a group of \"forever chemicals\" that spread very quickly and very far in ground water polluting it permanently.  Water wells near certain airports where any foam fire fighting or training activities occurred up to 2010 are likely to be contaminated by PFAS.\nA study concluded that of ~39 million groundwater wells 9-20% are at\nhigh risk of running dry\nif local groundwater levels decline by less than five meters, or – as with many areas and possibly more than half of major\naquifers\n[\n29\n]\n– continue to decline.\n[\n30\n]\n[\n31\n]\n[\nfurther explanation needed\n]\nSociety and culture\n[\nedit\n]\nWater use,\nTacuinum Sanitatis\n,\nBiblioteca Casanatense\n(14th century)\nSprings\nand wells have had\ncultural significance\nsince\nprehistoric\ntimes, leading to the foundation of towns such as\nWells\nand\nBath\nin\nSomerset\n.  Interest in health benefits led to the growth of\nspa towns\nincluding many with\nwells\nin their name, examples being\nLlandrindod Wells\nand\nRoyal Tunbridge Wells\n.\n[\n32\n]\nEratosthenes\nis sometimes claimed to have used a well in his calculation of the\nEarth's circumference\n; however, this is just a simplification used in a shorter explanation of\nCleomedes\n, since Eratosthenes had used a more elaborate and precise method.\n[\n33\n]\nMany incidents in the\nBible\ntake place around wells, such as the finding of a wife for\nIsaac\nin\nGenesis\nand\nJesus\n's talk with the Samaritan woman in the\nGospels\n.\n[\n34\n]\nA simple model for water well recovery\n[\nedit\n]\nDiagram of a water well partially filled to level\nz\nwith the top of the aquifer at\nz\nT\nFor a well with impermeable walls, the water in the well is resupplied from the bottom of the well. The rate at which water flows into the well will depend on the pressure difference between the ground water at the well bottom and the well water at the well bottom. The pressure of a column of water of height\nz\nwill be equal to the weight of the water in the column divided by the cross-sectional area of the column, so the pressure of the ground water a distance\nz\nT\nbelow the top of the water table will be:\nwhere\nρ\nis the mass density of the water and\ng\nis the acceleration due to gravity. When the water in the well is below the water table level, the pressure at the bottom of the well due to the water in the well will be less than\nP\ng\nand water will be forced into the well. Referring to the diagram, if\nz\nis the distance from the bottom of the well to the well water level and\nz\nT\nis the distance from the bottom of the well to the top of the water table, the pressure difference will be:\nApplying\nDarcy's law\n, the volume rate (\nF\n) at which water is forced into the well will be proportional to this pressure difference:\nwhere\nR\nis the resistance to the flow, which depends on the well cross section, the pressure gradient at the bottom of the well, and the characteristics of the substrate at the well bottom. (e.g., porosity). The volume flow rate into the well can be written as a function of the rate of change of the well water level:\nCombining the above three equations yields a simple differential equation in\nz\n:\nwhich may be solved:\nwhere\nz\n0\nis the well water level at time\nt=0\nand\nτ\nis the well time constant:\nNote that if\ndz\/dt\nfor a depleted well can be measured, it will be equal to\nand the time constant τ can be calculated. According to the above model, it will take an infinite amount of time for a well to fully recover, but if we consider a well that is 99% recovered to be \"practically\" recovered, the time for a well to practically recover from a level at\nz\nwill be:\nFor a well that is fully depleted (\nz=0\n) it would take a time of about\n4.6 τ\nto practically recover.\nThe above model does not take into account the depletion of the aquifer due to the pumping which lowered the well water level (See\naquifer test\nand\ngroundwater flow equation\n). Also, practical wells may have impermeable walls only up to, but not including the bedrock, which will give a larger surface area for water to enter the well.\n[\n35\n]\n[\n36\n]\nTypes of ancient wells\nBrick-lined well\nCastle well\n, for use in the castle\nCistern\n, ancient Greek\nStepwell\n, ancient India\nModern construction techniques\nBaptist well drilling\n, simple technique\nRodriguez well\n, for harvesting drinking water in polar regions\nSpring supply\n, piped water supply from the well\nUses\nHoly well\n, sacred wells in various religions\nAbraham's well\n, sacred well in Israel\nGhat\n, sacred in Hinduism and Buddhism\nDrainage and irrigation\nDrainage by wells\nShadoof\n, an irrigation tool that is used to lift water from a water source onto land or into another waterway or basin\nWashing\nLavoir\n, public place for washing clothes.\nFossil water\nHistory of water supply and sanitation\nAncient water conservation techniques\nSelf-supply of water and sanitation\n^\nPeltenburg, Edgar (2012). \"East Mediterranean water wells of the 9th–7th millennium BC\". In Klimscha, Florian (ed.).\nWasserwirtschaftliche Innovationen im archäologischen Kontext. Von den prähistorischen Anfängen bis zu den Metropolen der Antike\n. Rahden\/Westfalia: Leidorf. pp. \n69–\n82.\n^\nGalili, Ehud; Nir, Yaacov (1993). \"The submerged Pre-Pottery Neolithic water well of Atlit-Yam, northern Israel, and its palaeoenvironmental implications\".\nThe Holocene\n.\n3\n(3):\n265–\n270.\nBibcode\n:\n1993Holoc...3..265G\n.\ndoi\n:\n10.1177\/095968369300300309\n.\nS2CID\n \n130032420\n.\n^\nRybníček, Michal; Kočár, Petr; Muigg, Bernhard; Peška, Jaroslav; Sedláček, Radko; Tegel, Willy; Kolář, Tomáš (2020).\n\"World's oldest dendrochronologically dated archaeological wood construction\"\n.\nJournal of Archaeological Science\n.\n115\n105082.\nBibcode\n:\n2020JArSc.115j5082R\n.\ndoi\n:\n10.1016\/j.jas.2020.105082\n.\nS2CID\n \n213707193\n.\n^\n\"Kückhovener Brunnen – Dorfgemeinschaft Kückhoven E. V.\"\n[\npermanent dead link\n]\n^\nTegel W, Elburg R, Hakelberg D, Stäuble H, Büntgen U (2012).\n\"Early Neolithic Water Wells Reveal the World's Oldest Wood Architecture\"\n.\nPLOS ONE\n.\n7\n(12) e51374.\nBibcode\n:\n2012PLoSO...751374T\n.\ndoi\n:\n10.1371\/journal.pone.0051374\n.\nPMC\n \n3526582\n.\nPMID\n \n23284685\n.\n^\na\nb\nKuhn, Oliver (2004-06-30).\n\"Ancient Chinese Drilling\"\n.\nCanadian Society of Exploration Geophysicists\n.\n29\n(6).\n^\na\nb\nChang, Mingteh (2012).\nForest Hydrology: An Introduction to Water and Forests\n(3rd ed.). CRC Press (published November 1, 2012). p. 31.\nISBN\n \n978-1-4398-7994-8\n.\n^\nKoon, Wee Kek (July 25, 2015).\n\"How the ancient Chinese looked after their drinking water\"\n.\nSouth China Morning Post\n.\n^\n\"Sakieh explication\/difference vs Sakia\"\n.\nBritannica.com\n. Retrieved\n2011-12-19\n.\n^\n\"Sakia explication\"\n.\nBritannica.com\n. Retrieved\n2011-12-19\n.\n^\n\"Stone Age wells found in Cyprus\"\n.\nBBC News\n.\n^\nAshkenazi, Eli (November 9, 2012).\n\"Ancient Well Reveals Secrets of First Jezreel Valley Farmers\"\n.\nHaaretz\n.\n^\n\"ASTM International – Standards Worldwide\"\n.\nwww.astm.org\n. Archived from\nthe original\non 2020-08-01\n. Retrieved\n2019-02-01\n.\n^\nJoseph P. Riva Jr. and Gordon I. Atwater.\n\"petroleum\"\n.\nEncyclopædia Britannica\n. Retrieved\n2008-06-30\n.\n^\n\"Woodingdean Well\"\n. 2005\n. Retrieved\n26 Jan\n2010\n.\n^\n\"St. Patrick's Well\"\n. Umbriatravel.com\n. Retrieved\n2011-12-19\n.\n[\npermanent dead link\n]\n^\n\"How I drill a Well.\"\nPopular Science\n, April 1952, pp. 177–181.\n^\nAssociation), NKBA (National Kitchen and Bath (2013-10-29).\nKitchen & Bath Residential Construction and Systems\n. John Wiley & Sons.\nISBN\n \n978-1-118-71104-0\n.\n^\n\"Artesian Water and Artesian Wells | U.S. Geological Survey\"\n.\nwww.usgs.gov\n. 2018-10-09\n. Retrieved\n2026-03-23\n.\n^\nArnold, L.R.; Flynn, J.L.; Paschke, S.S. (2009-10-20).\n\"Design and installation of a groundwater monitoring-well network in the High Plains aquifer, Colorado\"\n.\nUSGS Report\n. Data Series. U.S. Geological Survey: 5.\nBibcode\n:\n2009usgs.rept....5A\n.\ndoi\n:\n10.3133\/ds456\n. Retrieved\n27 May\n2024\n.\n^\nDu Preez, Michael.\n\"ELECTRO-SEISMIC SURVEYS APPLIED TO MODDELING OF GROUNDWATER FLOW SYSTEMS\"\n(PDF)\n. Bloemfontein, South Africa. Archived from\nthe original\n(PDF)\non 31 May 2011\n. Retrieved\n21 April\n2011\n.\n^\na\nb\nc\nd\ne\nCommittee on Environmental Health; Committee on Infectious Diseases (2009).\n\"Drinking water from private wells and risks to children\"\n.\nPediatrics\n.\n123\n(6):\n1599–\n1605.\ndoi\n:\n10.1542\/peds.2009-0751\n.\nPMID\n \n19482772\n.\n^\nWiebe, Andrew J.; Rudolph, David L.; Pasha, Ehsan; Brook, Jacqueline M.; Christie, Mike; Menkveld, Paul G. (2021).\n\"Impacts of Event-Based Recharge on the Vulnerability of Public Supply Wells\"\n.\nSustainability\n.\n13\n(14): 7695.\nBibcode\n:\n2021Sust...13.7695W\n.\ndoi\n:\n10.3390\/su13147695\n.\nISSN\n \n2071-1050\n.\n^\nAssociation, American Water Works (2003).\nWater Sources\n. American Water Works Association.\nISBN\n \n978-1-58321-229-5\n.\n^\nMeulemans, C. C. E. (1987-09-01). \"The Basic Principles of UV–Disinfection of Water\".\nOzone: Science & Engineering\n.\n9\n(4):\n299–\n313.\nBibcode\n:\n1987OzSE....9..299M\n.\ndoi\n:\n10.1080\/01919518708552146\n.\nISSN\n \n0191-9512\n.\n^\n\"Soil salination by placement of water wells mentioned in India\"\n. Ngm.nationalgeographic.com. 2002-10-17. Archived from\nthe original\non May 22, 2009\n. Retrieved\n2011-12-19\n.\n^\n\"Practical Answers – Handpumps\"\n. Practicalaction.org\n. Retrieved\n2011-12-19\n.\n^\n\"Treadle pump\"\n. Dev.practicalaction.org\n. Retrieved\n2011-12-19\n.\n^\nFamiglietti, James S.; Ferguson, Grant (23 April 2021).\n\"The hidden crisis beneath our feet\"\n.\nScience\n.\n372\n(6540):\n344–\n345.\nBibcode\n:\n2021Sci...372..344F\n.\ndoi\n:\n10.1126\/science.abh2867\n.\nPMID\n \n33888627\n.\nS2CID\n \n233353241\n. Retrieved\n10 May\n2021\n.\n^\n\"The largest assessment of global groundwater wells finds many are at risk of drying up\"\n.\nScienceDaily\n. Retrieved\n10 May\n2021\n.\n^\nJasechko, Scott; Perrone, Debra (23 April 2021).\n\"Global groundwater wells at risk of running dry\"\n.\nScience\n.\n372\n(6540):\n418–\n421.\nBibcode\n:\n2021Sci...372..418J\n.\ndoi\n:\n10.1126\/science.abc2755\n.\nISSN\n \n0036-8075\n.\nPMID\n \n33888642\n.\nS2CID\n \n233353207\n. Retrieved\n10 May\n2021\n.\n^\nBurr, Thomas Benge (1766).\nThe History of Tunbridge Wells\n. London. Archived from\nthe original\non 2021-01-31\n. Retrieved\n2019-10-09\n.\n^\nRusso, Lucio\n(2004).\nThe Forgotten Revolution\n. Berlin: Springer. pp. \n273–\n277.\n^\nBromiley, Geoffrey W. (1982),\nInternational Standard Bible Encyclopedia: E-J\n, Wm. B. Eerdmans Publishing, p. 955,\nISBN\n \n978-0-8028-3782-0\n^\n\"Well Flow Equations\"\n(PDF)\n. Cal Poly Humboldt, Department of Geology\n. Retrieved\nJune 13,\n2022\n.\n^\n\"How Much Water Can the Well Deliver\"\n. Inspectapedia\n. Retrieved\nJune 13,\n2022\n.\nDriscoll, F. (1986).\nGroundwater and Wells\n.\nSt. Paul\n: Johnson Filtration Systems.\nISBN\n \n978-0-9616456-0-1\n.\nRaymond Rowles (1995).\nDrilling for Water\n(2nd ed.). Avebury, Cranfield University.\nISBN\n \n1-85628-984-2\n.\nSustainable Groundwater Development theme of the Rural Water Supply Network (RWSN)\nWater Portal – Akvopedia\nArchived\n2014-10-18 at the\nWayback Machine\nSustainable Sanitation and Water Management Toolbox\nU.S. Centers for Disease Control and Prevention (CDC) Healthy Water – Water Wells\nSite covering well basics, guidelines for proper siting and location of wells to avoid contamination, well testing, diseases related to wells, emergency well treatment and other topics.\nUS Geological Survey – Ground water: Wells\nUS Geological Survey – Water Science Pictures Flowing Artesian Well\nDrilling wells 18 extremely useful questions and answers\nAmerican Ground Water Trust\nLifewater International Technical Library\nArchived\n2013-06-16 at the\nWayback Machine\nWell Construction Technical Resources for NGOs","attrs_markdown":"[Jump to content](https:\/\/en.wikipedia.org\/wiki\/Well#bodyContent)\n\nMain menu\n\nMain menu\n\nmove to sidebar\n\nhide\n\nNavigation\n\n- [Main page](https:\/\/en.wikipedia.org\/wiki\/Main_Page \"Visit the main page [z]\")\n- [Contents](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Contents \"Guides to browsing Wikipedia\")\n- [Current events](https:\/\/en.wikipedia.org\/wiki\/Portal:Current_events \"Articles related to current events\")\n- [Random article](https:\/\/en.wikipedia.org\/wiki\/Special:Random \"Visit a randomly selected article [x]\")\n- [About Wikipedia](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:About \"Learn about Wikipedia and how it works\")\n- [Contact us](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Contact_us \"How to contact Wikipedia\")\n\nContribute\n\n- [Help](https:\/\/en.wikipedia.org\/wiki\/Help:Contents \"Guidance on how to use and edit Wikipedia\")\n- [Learn to edit](https:\/\/en.wikipedia.org\/wiki\/Help:Introduction \"Learn how to edit Wikipedia\")\n- [Community portal](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Community_portal \"The hub for editors\")\n- [Recent changes](https:\/\/en.wikipedia.org\/wiki\/Special:RecentChanges \"A list of recent changes to Wikipedia [r]\")\n- [Upload file](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:File_upload_wizard \"Add images or other media for use on Wikipedia\")\n- [Special pages](https:\/\/en.wikipedia.org\/wiki\/Special:SpecialPages \"A list of all special pages [q]\")\n\n[![](https:\/\/en.wikipedia.org\/static\/images\/icons\/enwiki-25.svg) ![Wikipedia](https:\/\/en.wikipedia.org\/static\/images\/mobile\/copyright\/wikipedia-wordmark-en-25.svg) ![The Free Encyclopedia](https:\/\/en.wikipedia.org\/static\/images\/mobile\/copyright\/wikipedia-tagline-en-25.svg)](https:\/\/en.wikipedia.org\/wiki\/Main_Page)\n\n[Search](https:\/\/en.wikipedia.org\/wiki\/Special:Search \"Search Wikipedia [f]\")\n\nAppearance\n\n- [Donate](https:\/\/donate.wikimedia.org\/?wmf_source=donate&wmf_medium=sidebar&wmf_campaign=en.wikipedia.org&uselang=en)\n- [Create account](https:\/\/en.wikipedia.org\/w\/index.php?title=Special:CreateAccount&returnto=Well \"You are encouraged to create an account and log in; however, it is not mandatory\")\n- [Log in](https:\/\/en.wikipedia.org\/w\/index.php?title=Special:UserLogin&returnto=Well \"You're encouraged to log in; however, it's not mandatory. [o]\")\n\nPersonal tools\n\n- [Donate](https:\/\/donate.wikimedia.org\/?wmf_source=donate&wmf_medium=sidebar&wmf_campaign=en.wikipedia.org&uselang=en)\n- [Create account](https:\/\/en.wikipedia.org\/w\/index.php?title=Special:CreateAccount&returnto=Well \"You are encouraged to create an account and log in; however, it is not mandatory\")\n- [Log in](https:\/\/en.wikipedia.org\/w\/index.php?title=Special:UserLogin&returnto=Well \"You're encouraged to log in; however, it's not mandatory. [o]\")\n\n## Contents\nmove to sidebar\n\nhide\n\n- [(Top)](https:\/\/en.wikipedia.org\/wiki\/Well)\n- [1 History](https:\/\/en.wikipedia.org\/wiki\/Well#History)\n- [2 Types](https:\/\/en.wikipedia.org\/wiki\/Well#Types)\n  Toggle Types subsection\n  - [2\\.1 Dug wells](https:\/\/en.wikipedia.org\/wiki\/Well#Dug_wells)\n  - [2\\.2 Driven wells](https:\/\/en.wikipedia.org\/wiki\/Well#Driven_wells)\n  - [2\\.3 Drilled wells](https:\/\/en.wikipedia.org\/wiki\/Well#Drilled_wells)\n- [3 Classification](https:\/\/en.wikipedia.org\/wiki\/Well#Classification)\n- [4 Siting](https:\/\/en.wikipedia.org\/wiki\/Well#Siting)\n- [5 Contamination](https:\/\/en.wikipedia.org\/wiki\/Well#Contamination)\n  Toggle Contamination subsection\n  - [5\\.1 Pathogens](https:\/\/en.wikipedia.org\/wiki\/Well#Pathogens)\n  - [5\\.2 Chemical contamination](https:\/\/en.wikipedia.org\/wiki\/Well#Chemical_contamination)\n  - [5\\.3 Prevention](https:\/\/en.wikipedia.org\/wiki\/Well#Prevention)\n  - [5\\.4 Mitigation](https:\/\/en.wikipedia.org\/wiki\/Well#Mitigation)\n- [6 Environmental problems](https:\/\/en.wikipedia.org\/wiki\/Well#Environmental_problems)\n  Toggle Environmental problems subsection\n  - [6\\.1 Soil salination](https:\/\/en.wikipedia.org\/wiki\/Well#Soil_salination)\n  - [6\\.2 Methane](https:\/\/en.wikipedia.org\/wiki\/Well#Methane)\n  - [6\\.3 PFAS\/PFOS Fire fighting foam](https:\/\/en.wikipedia.org\/wiki\/Well#PFAS\/PFOS_Fire_fighting_foam)\n- [7 Water security](https:\/\/en.wikipedia.org\/wiki\/Well#Water_security)\n- [8 Society and culture](https:\/\/en.wikipedia.org\/wiki\/Well#Society_and_culture)\n- [9 A simple model for water well recovery](https:\/\/en.wikipedia.org\/wiki\/Well#A_simple_model_for_water_well_recovery)\n- [10 Similar and related water structures](https:\/\/en.wikipedia.org\/wiki\/Well#Similar_and_related_water_structures)\n- [11 See also](https:\/\/en.wikipedia.org\/wiki\/Well#See_also)\n- [12 References](https:\/\/en.wikipedia.org\/wiki\/Well#References)\n  Toggle References subsection\n  - [12\\.1 Bibliography](https:\/\/en.wikipedia.org\/wiki\/Well#Bibliography)\n- [13 External links](https:\/\/en.wikipedia.org\/wiki\/Well#External_links)\n\nToggle the table of contents\n\n# Well\n123 languages\n\n- [Alemannisch](https:\/\/als.wikipedia.org\/wiki\/Brunnen \"Brunnen – Alemannic\")\n- [Aragonés](https:\/\/an.wikipedia.org\/wiki\/Pozo \"Pozo – Aragonese\")\n- [अंगिका](https:\/\/anp.wikipedia.org\/wiki\/%E0%A4%87%E0%A4%A8%E0%A4%BE%E0%A4%B0%E0%A4%BE \"इनारा – Angika\")\n- [العربية](https:\/\/ar.wikipedia.org\/wiki\/%D8%A8%D8%A6%D8%B1 \"بئر – Arabic\")\n- [অসমীয়া](https:\/\/as.wikipedia.org\/wiki\/%E0%A6%95%E0%A7%81%E0%A6%81%E2%80%8C%E0%A7%B1%E0%A6%BE \"কুঁ‌ৱা – Assamese\")\n- [Asturianu](https:\/\/ast.wikipedia.org\/wiki\/Pozu \"Pozu – Asturian\")\n- [Aymar aru](https:\/\/ay.wikipedia.org\/wiki\/Phuju \"Phuju – Aymara\")\n- [Azərbaycanca](https:\/\/az.wikipedia.org\/wiki\/Quyu \"Quyu – Azerbaijani\")\n- [Basa Bali](https:\/\/ban.wikipedia.org\/wiki\/S%C3%A9m%C3%A9r \"Sémér – Balinese\")\n- [Boarisch](https:\/\/bar.wikipedia.org\/wiki\/Brunn \"Brunn – Bavarian\")\n- [Žemaitėška](https:\/\/bat-smg.wikipedia.org\/wiki\/%C5%A0oln%C4%97s \"Šolnės – Samogitian\")\n- [Bikol Central](https:\/\/bcl.wikipedia.org\/wiki\/Bubon \"Bubon – Central Bikol\")\n- [Беларуская (тарашкевіца)](https:\/\/be-tarask.wikipedia.org\/wiki\/%D0%A1%D1%82%D1%83%D0%B4%D0%BD%D1%8F \"Студня – Belarusian (Taraškievica orthography)\")\n- [Беларуская](https:\/\/be.wikipedia.org\/wiki\/%D0%9A%D0%B0%D0%BB%D0%BE%D0%B4%D0%B7%D0%B5%D0%B6 \"Калодзеж – Belarusian\")\n- [Български](https:\/\/bg.wikipedia.org\/wiki\/%D0%92%D0%BE%D0%B4%D0%B5%D0%BD_%D0%BA%D0%BB%D0%B0%D0%B4%D0%B5%D0%BD%D0%B5%D1%86 \"Воден кладенец – Bulgarian\")\n- [भोजपुरी](https:\/\/bh.wikipedia.org\/wiki\/%E0%A4%87%E0%A4%A8%E0%A4%BE%E0%A4%B0 \"इनार – Bhojpuri\")\n- [বাংলা](https:\/\/bn.wikipedia.org\/wiki\/%E0%A6%95%E0%A7%82%E0%A6%AA \"কূপ – Bangla\")\n- [Brezhoneg](https:\/\/br.wikipedia.org\/wiki\/Pu%C3%B1s \"Puñs – Breton\")\n- [Bosanski](https:\/\/bs.wikipedia.org\/wiki\/Bunar \"Bunar – Bosnian\")\n- [Català](https:\/\/ca.wikipedia.org\/wiki\/Pou \"Pou – Catalan\")\n- [閩東語 \/ Mìng-dĕ̤ng-ngṳ̄](https:\/\/cdo.wikipedia.org\/wiki\/Ci%C4%81ng \"Ciāng – Mindong\")\n- [Tsetsêhestâhese](https:\/\/chy.wikipedia.org\/wiki\/V%C3%B3t%C3%A2h%C3%A1%C3%A9no \"Vótâháéno – Cheyenne\")\n- [Čeština](https:\/\/cs.wikipedia.org\/wiki\/Studna \"Studna – Czech\")\n- [Чӑвашла](https:\/\/cv.wikipedia.org\/wiki\/%C3%87%C4%83%D0%BB \"Çăл – Chuvash\")\n- [Dansk](https:\/\/da.wikipedia.org\/wiki\/Br%C3%B8nd \"Brønd – Danish\")\n- [Deutsch](https:\/\/de.wikipedia.org\/wiki\/Brunnen \"Brunnen – German\")\n- [Zazaki](https:\/\/diq.wikipedia.org\/wiki\/Bir_\\(co%C4%9Frafya\\) \"Bir (coğrafya) – Dimli\")\n- [Ελληνικά](https:\/\/el.wikipedia.org\/wiki\/%CE%A0%CE%B7%CE%B3%CE%AC%CE%B4%CE%B9 \"Πηγάδι – Greek\")\n- [Esperanto](https:\/\/eo.wikipedia.org\/wiki\/Puto \"Puto – Esperanto\")\n- [Español](https:\/\/es.wikipedia.org\/wiki\/Pozo \"Pozo – Spanish\")\n- [Eesti](https:\/\/et.wikipedia.org\/wiki\/Kaev \"Kaev – Estonian\")\n- [Euskara](https:\/\/eu.wikipedia.org\/wiki\/Putzu \"Putzu – Basque\")\n- [فارسی](https:\/\/fa.wikipedia.org\/wiki\/%DA%86%D8%A7%D9%87_%D8%A2%D8%A8 \"چاه آب – Persian\")\n- [Suomi](https:\/\/fi.wikipedia.org\/wiki\/Kaivo \"Kaivo – Finnish\")\n- [Français](https:\/\/fr.wikipedia.org\/wiki\/Puits_%C3%A0_eau \"Puits à eau – French\")\n- [Nordfriisk](https:\/\/frr.wikipedia.org\/wiki\/Suas \"Suas – Northern Frisian\")\n- [Gaeilge](https:\/\/ga.wikipedia.org\/wiki\/Tobar \"Tobar – Irish\")\n- [Galego](https:\/\/gl.wikipedia.org\/wiki\/Pozo \"Pozo – Galician\")\n- [Avañe'ẽ](https:\/\/gn.wikipedia.org\/wiki\/Ykua \"Ykua – Guarani\")\n- [ગુજરાતી](https:\/\/gu.wikipedia.org\/wiki\/%E0%AA%95%E0%AB%82%E0%AA%B5%E0%AB%8B \"કૂવો – Gujarati\")\n- [Gungbe](https:\/\/guw.wikipedia.org\/wiki\/Dot%E1%BB%8D \"Dotọ – Gun\")\n- [Hausa](https:\/\/ha.wikipedia.org\/wiki\/Rijiya_Mai_Zurfi \"Rijiya Mai Zurfi – Hausa\")\n- [עברית](https:\/\/he.wikipedia.org\/wiki\/%D7%91%D7%90%D7%A8_%D7%9E%D7%99%D7%9D \"באר מים – Hebrew\")\n- [हिन्दी](https:\/\/hi.wikipedia.org\/wiki\/%E0%A4%95%E0%A5%81%E0%A4%86%E0%A4%81 \"कुआँ – Hindi\")\n- [Hrvatski](https:\/\/hr.wikipedia.org\/wiki\/Zdenac \"Zdenac – Croatian\")\n- [Kreyòl ayisyen](https:\/\/ht.wikipedia.org\/wiki\/Pwi \"Pwi – Haitian Creole\")\n- [Magyar](https:\/\/hu.wikipedia.org\/wiki\/K%C3%BAt \"Kút – Hungarian\")\n- [Հայերեն](https:\/\/hy.wikipedia.org\/wiki\/%D5%8B%D6%80%D5%B0%D5%B8%D6%80_\\(%D5%BB%D6%80%D5%A1%D5%BF%D5%A5%D5%AD%D5%B6%D5%AB%D5%AF%D5%A1%D5%AF%D5%A1%D5%B6_%D5%AF%D5%A1%D5%BC%D5%B8%D6%82%D5%B5%D6%81\\) \"Ջրհոր (ջրատեխնիկական կառույց) – Armenian\")\n- [Արեւմտահայերէն](https:\/\/hyw.wikipedia.org\/wiki\/%D5%8B%D6%80%D5%B0%D5%B8%D6%80 \"Ջրհոր – Western Armenian\")\n- [Interlingua](https:\/\/ia.wikipedia.org\/wiki\/Puteo \"Puteo – Interlingua\")\n- [Bahasa Indonesia](https:\/\/id.wikipedia.org\/wiki\/Sumur \"Sumur – Indonesian\")\n- [Iñupiatun](https:\/\/ik.wikipedia.org\/wiki\/Nivviaq \"Nivviaq – Inupiaq\")\n- [Italiano](https:\/\/it.wikipedia.org\/wiki\/Pozzo \"Pozzo – Italian\")\n- [日本語](https:\/\/ja.wikipedia.org\/wiki\/%E4%BA%95%E6%88%B8 \"井戸 – Japanese\")\n- [Jawa](https:\/\/jv.wikipedia.org\/wiki\/Sumur \"Sumur – Javanese\")\n- [Қазақша](https:\/\/kk.wikipedia.org\/wiki\/%D2%9A%D2%B1%D0%B4%D1%8B%D2%9B \"Құдық – Kazakh\")\n- [ಕನ್ನಡ](https:\/\/kn.wikipedia.org\/wiki\/%E0%B2%AC%E0%B2%BE%E0%B2%B5%E0%B2%BF \"ಬಾವಿ – Kannada\")\n- [한국어](https:\/\/ko.wikipedia.org\/wiki\/%EC%9A%B0%EB%AC%BC \"우물 – Korean\")\n- [کٲشُر](https:\/\/ks.wikipedia.org\/wiki\/%DA%A9%D8%B1%D9%9B%DB%8C%D9%88%D9%97%D9%84 \"کرٛیوٗل – Kashmiri\")\n- [Kurdî](https:\/\/ku.wikipedia.org\/wiki\/%C3%87al \"Çal – Kurdish\")\n- [Коми](https:\/\/kv.wikipedia.org\/wiki\/%D3%A6%D1%88%D0%BC%D3%A7%D1%81 \"Ӧшмӧс – Komi\")\n- [Latina](https:\/\/la.wikipedia.org\/wiki\/Puteus \"Puteus – Latin\")\n- [Lëtzebuergesch](https:\/\/lb.wikipedia.org\/wiki\/P%C3%ABtz \"Pëtz – Luxembourgish\")\n- [Limburgs](https:\/\/li.wikipedia.org\/wiki\/Waterp%C3%B6t \"Waterpöt – Limburgish\")\n- [Lombard](https:\/\/lmo.wikipedia.org\/wiki\/Pozz \"Pozz – Lombard\")\n- [Lietuvių](https:\/\/lt.wikipedia.org\/wiki\/%C5%A0ulinys \"Šulinys – Lithuanian\")\n- [Latviešu](https:\/\/lv.wikipedia.org\/wiki\/Aka \"Aka – Latvian\")\n- [Minangkabau](https:\/\/min.wikipedia.org\/wiki\/Sumua \"Sumua – Minangkabau\")\n- [Македонски](https:\/\/mk.wikipedia.org\/wiki\/%D0%91%D1%83%D0%BD%D0%B0%D1%80 \"Бунар – Macedonian\")\n- [മലയാളം](https:\/\/ml.wikipedia.org\/wiki\/%E0%B4%95%E0%B4%BF%E0%B4%A3%E0%B5%BC \"കിണർ – Malayalam\")\n- [मराठी](https:\/\/mr.wikipedia.org\/wiki\/%E0%A4%B5%E0%A4%BF%E0%A4%B9%E0%A5%80%E0%A4%B0 \"विहीर – Marathi\")\n- [Bahasa Melayu](https:\/\/ms.wikipedia.org\/wiki\/Perigi \"Perigi – Malay\")\n- [မြန်မာဘာသာ](https:\/\/my.wikipedia.org\/wiki\/%E1%80%A1%E1%80%9D%E1%80%AE%E1%80%85%E1%80%AD%E1%80%90%E1%80%BD%E1%80%84%E1%80%BA%E1%80%B8 \"အဝီစိတွင်း – Burmese\")\n- [Napulitano](https:\/\/nap.wikipedia.org\/wiki\/Puzzo \"Puzzo – Neapolitan\")\n- [Plattdüütsch](https:\/\/nds.wikipedia.org\/wiki\/Sood \"Sood – Low German\")\n- [नेपाली](https:\/\/ne.wikipedia.org\/wiki\/%E0%A4%AA%E0%A4%A7%E0%A5%87%E0%A4%81%E0%A4%B0%E0%A4%BE \"पधेँरा – Nepali\")\n- [Li Niha](https:\/\/nia.wikipedia.org\/wiki\/Hele \"Hele – Nias\")\n- [Nederlands](https:\/\/nl.wikipedia.org\/wiki\/Waterput \"Waterput – Dutch\")\n- [Norsk nynorsk](https:\/\/nn.wikipedia.org\/wiki\/Brunn \"Brunn – Norwegian Nynorsk\")\n- [Norsk bokmål](https:\/\/no.wikipedia.org\/wiki\/Br%C3%B8nn \"Brønn – Norwegian Bokmål\")\n- [Nouormand](https:\/\/nrm.wikipedia.org\/wiki\/Pyit \"Pyit – Norman\")\n- [Occitan](https:\/\/oc.wikipedia.org\/wiki\/Potz \"Potz – Occitan\")\n- [Ирон](https:\/\/os.wikipedia.org\/wiki\/%D0%A6%D1%8A%D0%B0%D0%B9 \"Цъай – Ossetic\")\n- [ਪੰਜਾਬੀ](https:\/\/pa.wikipedia.org\/wiki\/%E0%A8%96%E0%A9%82%E0%A8%B9 \"ਖੂਹ – Punjabi\")\n- [Picard](https:\/\/pcd.wikipedia.org\/wiki\/Pure_\\(treu\\) \"Pure (treu) – Picard\")\n- [Deitsch](https:\/\/pdc.wikipedia.org\/wiki\/Brunne \"Brunne – Pennsylvania German\")\n- [Polski](https:\/\/pl.wikipedia.org\/wiki\/Studnia \"Studnia – Polish\")\n- [Piemontèis](https:\/\/pms.wikipedia.org\/wiki\/Poss_d%27eva \"Poss d'eva – Piedmontese\")\n- [پنجابی](https:\/\/pnb.wikipedia.org\/wiki\/%DA%A9%DA%BE%D9%88%DB%81 \"کھوہ – Western Punjabi\")\n- [پښتو](https:\/\/ps.wikipedia.org\/wiki\/%D8%AF_%D8%A7%D8%A8%D9%88_%DA%85%D8%A7%DA%AB%D8%A7%D9%86%DB%90 \"د ابو څاګانې – Pashto\")\n- [Português](https:\/\/pt.wikipedia.org\/wiki\/Po%C3%A7o \"Poço – Portuguese\")\n- [Runa Simi](https:\/\/qu.wikipedia.org\/wiki\/Yaku_hurquna \"Yaku hurquna – Quechua\")\n- [Română](https:\/\/ro.wikipedia.org\/wiki\/Pu%C8%9B_de_ap%C4%83 \"Puț de apă – Romanian\")\n- [Руски](https:\/\/rsk.wikipedia.org\/wiki\/%D0%A1%D1%82%D1%83%D0%B4%D0%BD%D1%8F \"Студня – Pannonian Rusyn\")\n- [Русский](https:\/\/ru.wikipedia.org\/wiki\/%D0%9A%D0%BE%D0%BB%D0%BE%D0%B4%D0%B5%D1%86 \"Колодец – Russian\")\n- [Sicilianu](https:\/\/scn.wikipedia.org\/wiki\/Puzzu \"Puzzu – Sicilian\")\n- [Srpskohrvatski \/ српскохрватски](https:\/\/sh.wikipedia.org\/wiki\/Bunar \"Bunar – Serbo-Croatian\")\n- [Simple English](https:\/\/simple.wikipedia.org\/wiki\/Well \"Well – Simple English\")\n- [Slovenčina](https:\/\/sk.wikipedia.org\/wiki\/Stud%C5%88a \"Studňa – Slovak\")\n- [Slovenščina](https:\/\/sl.wikipedia.org\/wiki\/Vodnjak \"Vodnjak – Slovenian\")\n- [ChiShona](https:\/\/sn.wikipedia.org\/wiki\/Tsime \"Tsime – Shona\")\n- [Soomaaliga](https:\/\/so.wikipedia.org\/wiki\/Ceel \"Ceel – Somali\")\n- [Shqip](https:\/\/sq.wikipedia.org\/wiki\/Pusi \"Pusi – Albanian\")\n- [Српски \/ srpski](https:\/\/sr.wikipedia.org\/wiki\/%D0%91%D1%83%D0%BD%D0%B0%D1%80 \"Бунар – Serbian\")\n- [Sesotho](https:\/\/st.wikipedia.org\/wiki\/Sediba \"Sediba – Southern Sotho\")\n- [Sunda](https:\/\/su.wikipedia.org\/wiki\/Sumur \"Sumur – Sundanese\")\n- [Svenska](https:\/\/sv.wikipedia.org\/wiki\/Brunn \"Brunn – Swedish\")\n- [Sakizaya](https:\/\/szy.wikipedia.org\/wiki\/tebun \"tebun – Sakizaya\")\n- [தமிழ்](https:\/\/ta.wikipedia.org\/wiki\/%E0%AE%95%E0%AE%BF%E0%AE%A3%E0%AE%B1%E0%AF%81 \"கிணறு – Tamil\")\n- [తెలుగు](https:\/\/te.wikipedia.org\/wiki\/%E0%B0%AC%E0%B0%BE%E0%B0%B5%E0%B0%BF \"బావి – Telugu\")\n- [Tagalog](https:\/\/tl.wikipedia.org\/wiki\/Balon \"Balon – Tagalog\")\n- [Tolışi](https:\/\/tly.wikipedia.org\/wiki\/Col \"Col – Talysh\")\n- [Türkçe](https:\/\/tr.wikipedia.org\/wiki\/Kuyu \"Kuyu – Turkish\")\n- [Українська](https:\/\/uk.wikipedia.org\/wiki\/%D0%9A%D1%80%D0%B8%D0%BD%D0%B8%D1%86%D1%8F \"Криниця – Ukrainian\")\n- [اردو](https:\/\/ur.wikipedia.org\/wiki\/%DA%A9%D9%86%D9%88%D8%A7%DA%BA \"کنواں – Urdu\")\n- [Oʻzbekcha \/ ўзбекча](https:\/\/uz.wikipedia.org\/wiki\/Quduq \"Quduq – Uzbek\")\n- [Vepsän kel’](https:\/\/vep.wikipedia.org\/wiki\/Kaiv \"Kaiv – Veps\")\n- [Tiếng Việt](https:\/\/vi.wikipedia.org\/wiki\/Gi%E1%BA%BFng \"Giếng – Vietnamese\")\n- [Walon](https:\/\/wa.wikipedia.org\/wiki\/Pousse \"Pousse – Walloon\")\n- [吴语](https:\/\/wuu.wikipedia.org\/wiki\/%E4%BA%95 \"井 – Wu\")\n- [閩南語 \/ Bân-lâm-gí](https:\/\/zh-min-nan.wikipedia.org\/wiki\/Ch%C3%A9%E2%81%BF \"Chéⁿ – Minnan\")\n- [粵語](https:\/\/zh-yue.wikipedia.org\/wiki\/%E4%BA%95 \"井 – Cantonese\")\n- [中文](https:\/\/zh.wikipedia.org\/wiki\/%E4%BA%95 \"井 – Chinese\")\n\n[Edit links](https:\/\/www.wikidata.org\/wiki\/Special:EntityPage\/Q43483#sitelinks-wikipedia \"Edit interlanguage links\")\n\n- [Article](https:\/\/en.wikipedia.org\/wiki\/Well \"View the content page [c]\")\n- [Talk](https:\/\/en.wikipedia.org\/wiki\/Talk:Well \"Discuss improvements to the content page [t]\")\n\nEnglish\n\n- [Read](https:\/\/en.wikipedia.org\/wiki\/Well)\n- [Edit](https:\/\/en.wikipedia.org\/w\/index.php?title=Well&action=edit \"Edit this page [e]\")\n- [View history](https:\/\/en.wikipedia.org\/w\/index.php?title=Well&action=history \"Past revisions of this page [h]\")\n\nTools\n\nTools\n\nmove to sidebar\n\nhide\n\nActions\n\n- [Read](https:\/\/en.wikipedia.org\/wiki\/Well)\n- [Edit](https:\/\/en.wikipedia.org\/w\/index.php?title=Well&action=edit \"Edit this page [e]\")\n- [View history](https:\/\/en.wikipedia.org\/w\/index.php?title=Well&action=history)\n\nGeneral\n\n- [What links here](https:\/\/en.wikipedia.org\/wiki\/Special:WhatLinksHere\/Well \"List of all English Wikipedia pages containing links to this page [j]\")\n- [Related changes](https:\/\/en.wikipedia.org\/wiki\/Special:RecentChangesLinked\/Well \"Recent changes in pages linked from this page [k]\")\n- [Upload file](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:File_Upload_Wizard \"Upload files [u]\")\n- [Permanent link](https:\/\/en.wikipedia.org\/w\/index.php?title=Well&oldid=1348155091 \"Permanent link to this revision of this page\")\n- [Page information](https:\/\/en.wikipedia.org\/w\/index.php?title=Well&action=info \"More information about this page\")\n- [Cite this page](https:\/\/en.wikipedia.org\/w\/index.php?title=Special:CiteThisPage&page=Well&id=1348155091&wpFormIdentifier=titleform \"Information on how to cite this page\")\n- [Get shortened URL](https:\/\/en.wikipedia.org\/w\/index.php?title=Special:UrlShortener&url=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FWell)\n\nPrint\/export\n\n- [Download as PDF](https:\/\/en.wikipedia.org\/w\/index.php?title=Special:DownloadAsPdf&page=Well&action=show-download-screen \"Download this page as a PDF file\")\n- [Printable version](https:\/\/en.wikipedia.org\/w\/index.php?title=Well&printable=yes \"Printable version of this page [p]\")\n\nIn other projects\n\n- [Wikimedia Commons](https:\/\/commons.wikimedia.org\/wiki\/Category:Water_wells)\n- [Wikidata item](https:\/\/www.wikidata.org\/wiki\/Special:EntityPage\/Q43483 \"Structured data on this page hosted by Wikidata [g]\")\n\nAppearance\n\nmove to sidebar\n\nhide\n\nFrom Wikipedia, the free encyclopedia\n\nExcavation or structure to provide access to groundwater\n\nThis article is about water wells. For other uses, see [Well (disambiguation)](https:\/\/en.wikipedia.org\/wiki\/Well_\\(disambiguation\\) \"Well (disambiguation)\").\n\n\"Village pump\" redirects here. For the set of Wikipedia discussion pages, see [Wikipedia:Village pump](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Village_pump \"Wikipedia:Village pump\").\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/0\/01\/Faryab-_village_dug_well.JPG\/250px-Faryab-_village_dug_well.JPG)](https:\/\/en.wikipedia.org\/wiki\/File:Faryab-_village_dug_well.JPG)\n\nA dug well in a village in [Faryab Province](https:\/\/en.wikipedia.org\/wiki\/Faryab_Province \"Faryab Province\"), [Afghanistan](https:\/\/en.wikipedia.org\/wiki\/Afghanistan \"Afghanistan\")\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/0\/02\/Well-cistern.jpg\/250px-Well-cistern.jpg)](https:\/\/en.wikipedia.org\/wiki\/File:Well-cistern.jpg)\n\nThe difference between a well and a [cistern](https:\/\/en.wikipedia.org\/wiki\/Cistern \"Cistern\") is in the source of the water: a cistern collects [rainwater](https:\/\/en.wikipedia.org\/wiki\/Rainwater \"Rainwater\") whereas a well draws from [groundwater](https:\/\/en.wikipedia.org\/wiki\/Groundwater \"Groundwater\").\n\nA **well** is an excavation or structure created on the earth by [digging](https:\/\/en.wikipedia.org\/wiki\/Digging \"Digging\"), driving, or [drilling](https:\/\/en.wikipedia.org\/wiki\/Drilling \"Drilling\") to access [liquid](https:\/\/en.wikipedia.org\/wiki\/Liquid \"Liquid\") resources, usually [water](https:\/\/en.wikipedia.org\/wiki\/Water \"Water\"). The oldest and most common kind of well is a water well, to access [groundwater](https:\/\/en.wikipedia.org\/wiki\/Groundwater \"Groundwater\") in underground [aquifers](https:\/\/en.wikipedia.org\/wiki\/Aquifer \"Aquifer\"). The well water is drawn up by a [pump](https:\/\/en.wikipedia.org\/wiki\/Pump \"Pump\"), or using containers, such as [buckets](https:\/\/en.wikipedia.org\/wiki\/Bucket \"Bucket\") that are raised mechanically or by hand. Water can also be [injected back into the aquifer](https:\/\/en.wikipedia.org\/wiki\/Aquifer_storage_and_recovery \"Aquifer storage and recovery\") through the well. Wells were first constructed at least eight thousand years ago and historically vary in construction from a sediment of a dry watercourse to the [qanats](https:\/\/en.wikipedia.org\/wiki\/Qanat \"Qanat\") of Iran, and the [stepwells](https:\/\/en.wikipedia.org\/wiki\/Stepwell \"Stepwell\") and [sakiehs](https:\/\/en.wikipedia.org\/wiki\/Sakia \"Sakia\") of India. Placing a lining in the well shaft helps create stability, and linings of wood or [wickerwork](https:\/\/en.wikipedia.org\/wiki\/Wicker \"Wicker\") date back at least as far as the [Iron Age](https:\/\/en.wikipedia.org\/wiki\/Iron_Age \"Iron Age\").\n\nWells have traditionally been sunk by hand digging, as is still the case in rural areas of the developing world. These wells are inexpensive and low-tech as they use mostly manual labour, and the structure can be lined with [brick](https:\/\/en.wikipedia.org\/wiki\/Brick \"Brick\") or stone as the excavation proceeds. A more modern method called [caissoning](https:\/\/en.wikipedia.org\/wiki\/Caisson_\\(engineering\\) \"Caisson (engineering)\") uses pre-cast reinforced concrete well rings that are lowered into the hole. Driven wells can be created in unconsolidated material with a well hole structure, which consists of a hardened drive point and a screen of perforated pipe, after which a pump is installed to collect the water. Deeper wells can be excavated by hand drilling methods or machine drilling, using a [bit](https:\/\/en.wikipedia.org\/wiki\/Drill_bit \"Drill bit\") in a [borehole](https:\/\/en.wikipedia.org\/wiki\/Borehole \"Borehole\"). Drilled wells are usually cased with a factory-made pipe composed of steel or plastic. Drilled wells can access water at much greater depths than dug wells.\n\nTwo broad classes of well are shallow or unconfined wells completed within the uppermost saturated [aquifer](https:\/\/en.wikipedia.org\/wiki\/Aquifer \"Aquifer\") at that location, and deep or confined wells, sunk through an impermeable stratum into an aquifer beneath. A collector well can be constructed adjacent to a freshwater lake or stream with water percolating through the intervening material. The site of a well can be selected by a [hydrogeologist](https:\/\/en.wikipedia.org\/wiki\/Hydrogeology \"Hydrogeology\"), or groundwater surveyor. Water may be pumped or hand drawn. Impurities from the surface can easily reach shallow sources and contamination of the supply by pathogens or chemical contaminants needs to be avoided. Well water typically contains more minerals in solution than surface water and may require [treatment](https:\/\/en.wikipedia.org\/wiki\/Water_treatment \"Water treatment\") before being potable. [Soil salination](https:\/\/en.wikipedia.org\/wiki\/Soil_salinity \"Soil salinity\") can occur as the water table falls and the surrounding soil begins to dry out. Another environmental problem is the potential for [methane](https:\/\/en.wikipedia.org\/wiki\/Methane \"Methane\") to seep into the water.\n\n## History\n\\[[edit](https:\/\/en.wikipedia.org\/w\/index.php?title=Well&action=edit&section=1 \"Edit section: History\")\\]\n\nSee also: [History of water supply and sanitation](https:\/\/en.wikipedia.org\/wiki\/History_of_water_supply_and_sanitation \"History of water supply and sanitation\")\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/7\/7b\/Tunis1960-150_hg.jpg\/250px-Tunis1960-150_hg.jpg)](https:\/\/en.wikipedia.org\/wiki\/File:Tunis1960-150_hg.jpg)\n\nCamel drawing water from a well, [Djerba](https:\/\/en.wikipedia.org\/wiki\/Djerba \"Djerba\") island, Tunisia, 1960\n\nVery early [Neolithic](https:\/\/en.wikipedia.org\/wiki\/Neolithic \"Neolithic\") wells are known from the [Eastern Mediterranean](https:\/\/en.wikipedia.org\/wiki\/Eastern_Mediterranean \"Eastern Mediterranean\").[\\[1\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-1) The oldest reliably dated well is from the [pre-pottery neolithic](https:\/\/en.wikipedia.org\/wiki\/Prehistoric_Cyprus#Aceramic_Neolithic \"Prehistoric Cyprus\") (PPN) site of Kissonerga-Mylouthkia on [Cyprus](https:\/\/en.wikipedia.org\/wiki\/Cyprus \"Cyprus\"). At around 8400 BC a shaft (well 116) of circular diameter was driven through limestone to reach an [aquifer](https:\/\/en.wikipedia.org\/wiki\/Aquifer \"Aquifer\") at a depth of 8 metres (26 ft). Well 2070 from Kissonerga-Mylouthkia, dating to the late PPN, reaches a depth of 13 metres (43 ft). Other slightly younger wells are known from this site and from neighbouring Parekklisha-Shillourokambos. A first stone lined[\\[2\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-2) well of 5.5 metres (18 ft) depth is documented from a drowned final PPN (c. 7000 BC) site at ['Atlit-Yam](https:\/\/en.wikipedia.org\/wiki\/Atlit_Yam \"Atlit Yam\") off the coast near modern [Haifa](https:\/\/en.wikipedia.org\/wiki\/Haifa \"Haifa\") in [Israel](https:\/\/en.wikipedia.org\/wiki\/Israel \"Israel\").\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/7\/74\/K%C3%BCckhoven_%28Erkelenz%29%2C_Brunnenbaureste_um_5300_v._Ch._.jpg\/120px-K%C3%BCckhoven_%28Erkelenz%29%2C_Brunnenbaureste_um_5300_v._Ch._.jpg)](https:\/\/en.wikipedia.org\/wiki\/File:K%C3%BCckhoven_\\(Erkelenz\\),_Brunnenbaureste_um_5300_v._Ch._.jpg)\n\nNeolithic [Linear Pottery culture](https:\/\/en.wikipedia.org\/wiki\/Linear_Pottery_culture \"Linear Pottery culture\") well, 5300 BC, [Erkelenz](https:\/\/en.wikipedia.org\/wiki\/Erkelenz \"Erkelenz\"), Germany\n\nWood-lined wells are known from the early Neolithic [Linear Pottery culture](https:\/\/en.wikipedia.org\/wiki\/Linear_Pottery_culture \"Linear Pottery culture\"), for example in Ostrov, Czech Republic, dated 5265 BC,[\\[3\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-3) Kückhoven (an outlying centre of [Erkelenz](https:\/\/en.wikipedia.org\/wiki\/Erkelenz \"Erkelenz\")), dated 5300 BC,[\\[4\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-4) and [Eythra](https:\/\/en.wikipedia.org\/wiki\/Eythra \"Eythra\") in Schletz (an outlying centre of [Asparn an der Zaya](https:\/\/en.wikipedia.org\/wiki\/Asparn_an_der_Zaya \"Asparn an der Zaya\")) in [Austria](https:\/\/en.wikipedia.org\/wiki\/Austria \"Austria\"), dated 5200 BC.[\\[5\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-5)\n\nThe Neolithic Chinese discovered and made extensive use of deep drilled groundwater for drinking.\\[*[citation needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Citation_needed \"Wikipedia:Citation needed\")*\\] The Chinese text *[The Book of Changes](https:\/\/en.wikipedia.org\/wiki\/I_Ching \"I Ching\")*, originally a divination text of the Western Zhou dynasty (1046 -771 BC), contains an entry describing how the ancient Chinese maintained their wells and protected their sources of water.[\\[6\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-Kuhn2004-6) A well excavated at the [Hemedu](https:\/\/en.wikipedia.org\/wiki\/Hemudu_culture \"Hemudu culture\") excavation site was believed to have been built during the neolithic era.[\\[7\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-Chang2012-7) The well was cased by four rows of logs with a square frame attached to them at the top of the well. 60 additional tile wells southwest of Beijing are also believed to have been built around 600 BC for drinking and irrigation.[\\[7\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-Chang2012-7)[\\[8\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-8)\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/7\/73\/Model_well%2C_burial_find%2C_China%2C_Han_dynasty%2C_206_BC_to_220_AD%2C_earthenware_-_%C3%96stasiatiska_museet%2C_Stockholm_-_DSC09578.JPG\/250px-Model_well%2C_burial_find%2C_China%2C_Han_dynasty%2C_206_BC_to_220_AD%2C_earthenware_-_%C3%96stasiatiska_museet%2C_Stockholm_-_DSC09578.JPG)](https:\/\/en.wikipedia.org\/wiki\/File:Model_well,_burial_find,_China,_Han_dynasty,_206_BC_to_220_AD,_earthenware_-_%C3%96stasiatiska_museet,_Stockholm_-_DSC09578.JPG)\n\nA Chinese ceramic model of a well with a water [pulley](https:\/\/en.wikipedia.org\/wiki\/Pulley \"Pulley\") system, excavated from a tomb of the [Han dynasty](https:\/\/en.wikipedia.org\/wiki\/Han_dynasty \"Han dynasty\") (202 BC – 220 AD) period\n\nIn [Egypt](https:\/\/en.wikipedia.org\/wiki\/Egypt \"Egypt\"), [shadoofs](https:\/\/en.wikipedia.org\/wiki\/Shadoof \"Shadoof\") and [sakias](https:\/\/en.wikipedia.org\/wiki\/Sakia \"Sakia\") are used.[\\[9\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-9)[\\[10\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-10) The sakia is much more efficient, as it can bring up water from a depth of 10 metres (versus the 3 metres of the shadoof). The sakia is the Egyptian version of the [noria](https:\/\/en.wikipedia.org\/wiki\/Noria \"Noria\"). Some of the world's oldest known wells, located in Cyprus, date to 7000–8,500 BC.[\\[11\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-11) Two wells from the Neolithic period, around 6500 BC, have been discovered in Israel. One is in Atlit, on the northern coast of Israel, and the other is in the Jezreel Valley.[\\[12\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-12)\n\nWells for other purposes came along much later, historically. The first recorded [salt well](https:\/\/en.wikipedia.org\/wiki\/Salt_well \"Salt well\") was dug in the Sichuan province of China around 2,250 years ago. This was the first time that ancient water well technology was applied successfully for the exploitation of salt, and marked the beginning of Sichuan's salt drilling industry.[\\[6\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-Kuhn2004-6) The earliest known [oil wells](https:\/\/en.wikipedia.org\/wiki\/Oil_well \"Oil well\") were also drilled in China, in 347 CE. These wells had depths of up to about 240 metres (790 ft) and were drilled using [bits](https:\/\/en.wikipedia.org\/wiki\/Drill_bit \"Drill bit\") attached to [bamboo](https:\/\/en.wikipedia.org\/wiki\/Bamboo \"Bamboo\") poles.[\\[13\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-ASTM-13) The oil was burned to evaporate [brine](https:\/\/en.wikipedia.org\/wiki\/Brine \"Brine\") and produce [salt](https:\/\/en.wikipedia.org\/wiki\/Sodium_chloride \"Sodium chloride\"). By the 10th century, extensive [bamboo](https:\/\/en.wikipedia.org\/wiki\/Bamboo \"Bamboo\") pipelines connected oil wells with salt springs. The ancient records of China and [Japan](https:\/\/en.wikipedia.org\/wiki\/Japan \"Japan\") are said to contain many allusions to the use of natural gas for lighting and heating. Petroleum was known as *Burning water* in Japan in the 7th century.[\\[14\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-EB1911-14)\n\n## Types\n\\[[edit](https:\/\/en.wikipedia.org\/w\/index.php?title=Well&action=edit&section=2 \"Edit section: Types\")\\]\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/7\/77\/Uwaynat_bin_Hussain_water_well_near_Simaisma.jpg\/250px-Uwaynat_bin_Hussain_water_well_near_Simaisma.jpg)](https:\/\/en.wikipedia.org\/wiki\/File:Uwaynat_bin_Hussain_water_well_near_Simaisma.jpg)\n\nWater well near [Simaisma](https:\/\/en.wikipedia.org\/wiki\/Simaisma \"Simaisma\"), eastern Qatar\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/b\/b8\/Leather_bucket_of_a_well.jpg\/250px-Leather_bucket_of_a_well.jpg)](https:\/\/en.wikipedia.org\/wiki\/File:Leather_bucket_of_a_well.jpg)\n\nLeather bucket used for the water well\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/a\/a6\/Well%2C_Historical_Village_%2C_Bhaini_Sahib%2C_Ludhyana_%2C_Punjab_%2C_India.JPG\/250px-Well%2C_Historical_Village_%2C_Bhaini_Sahib%2C_Ludhyana_%2C_Punjab_%2C_India.JPG)](https:\/\/en.wikipedia.org\/wiki\/File:Well,_Historical_Village_,_Bhaini_Sahib,_Ludhyana_,_Punjab_,_India.JPG)\n\nWell, Historical Village, Bhaini Sahib, [Ludhiana](https:\/\/en.wikipedia.org\/wiki\/Ludhiana \"Ludhiana\"), [Punjab](https:\/\/en.wikipedia.org\/wiki\/Punjab,_India \"Punjab, India\"), India\n\n### Dug wells\n\\[[edit](https:\/\/en.wikipedia.org\/w\/index.php?title=Well&action=edit&section=3 \"Edit section: Dug wells\")\\]\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/d\/d6\/Well.handdug.cased.mali.jpg\/250px-Well.handdug.cased.mali.jpg)](https:\/\/en.wikipedia.org\/wiki\/File:Well.handdug.cased.mali.jpg)\n\nView into a hand-dug well cased with concrete rings. [Ouelessebougou](https:\/\/en.wikipedia.org\/wiki\/Ouelessebougou \"Ouelessebougou\"), Mali.\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/c\/ca\/Well_In_Kerala.JPG\/250px-Well_In_Kerala.JPG)](https:\/\/en.wikipedia.org\/wiki\/File:Well_In_Kerala.JPG)\n\nA dug well in a village in [Kerala](https:\/\/en.wikipedia.org\/wiki\/Kerala \"Kerala\"), India\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/5\/57\/Open_Well_-_flower_bag_shaped_wall_and_podium_01.jpg\/250px-Open_Well_-_flower_bag_shaped_wall_and_podium_01.jpg)](https:\/\/en.wikipedia.org\/wiki\/File:Open_Well_-_flower_bag_shaped_wall_and_podium_01.jpg)\n\nWell with a flower bag-shaped wall and podium\n\nUntil recent centuries, all artificial wells were [pumpless](https:\/\/en.wikipedia.org\/wiki\/Pump \"Pump\") hand-dug wells of varying degrees of sophistication, and they remain a very important source of [potable water](https:\/\/en.wikipedia.org\/wiki\/Potable_water \"Potable water\") in some rural developing areas, where they are routinely dug and used today. Their indispensability has produced a number of literary references, literal and figurative, including the reference to the incident of [Jesus](https:\/\/en.wikipedia.org\/wiki\/Jesus \"Jesus\") meeting a woman at [Jacob](https:\/\/en.wikipedia.org\/wiki\/Jacob \"Jacob\")'s well ([John](https:\/\/en.wikipedia.org\/wiki\/Gospel_of_John \"Gospel of John\") 4:6) in the Bible and the \"[Ding Dong Bell](https:\/\/en.wikipedia.org\/wiki\/Ding_Dong_Bell \"Ding Dong Bell\")\" [nursery rhyme](https:\/\/en.wikipedia.org\/wiki\/Nursery_rhyme \"Nursery rhyme\") about a cat in a well.\n\nHand-dug wells are excavations with diameters large enough to accommodate one or more people with shovels digging down to below the [water table](https:\/\/en.wikipedia.org\/wiki\/Water_table \"Water table\"). The excavation is braced horizontally to avoid landslide or erosion endangering the people digging. They can be lined with stone or brick; extending this lining upwards above the ground surface to form a wall around the well serves to reduce both contamination and accidental falls into the well.\n\nA more modern method called [caissoning](https:\/\/en.wikipedia.org\/wiki\/Caisson_\\(engineering\\) \"Caisson (engineering)\") uses reinforced concrete or plain concrete pre-cast well rings that are lowered into the hole. A well-digging team digs under a cutting ring and the well column slowly sinks into the [aquifer](https:\/\/en.wikipedia.org\/wiki\/Aquifer \"Aquifer\"), whilst protecting the team from collapse of the well [bore](https:\/\/en.wikipedia.org\/wiki\/Borehole \"Borehole\").\n\nHand-dug wells are inexpensive and low tech (compared to drilling) and they use mostly manual labour to access groundwater in rural locations of developing countries. They may be built with a high degree of community participation, or by local entrepreneurs who specialize in hand-dug wells. They have been successfully excavated to 60 metres (200 ft). They have low operational and maintenance costs, in part because water can be extracted by hand, without a pump. The water often comes from an aquifer or groundwater, and can be easily deepened, which may be necessary if the ground water level drops, by telescoping the lining further down into the aquifer. The yield of existing hand dug wells may be improved by deepening or introducing vertical tunnels or perforated pipes.\n\nDrawbacks to hand-dug wells are numerous. It can be impractical to hand dig wells in areas where hard rock is present, and they can be time-consuming to dig and line even in favourable areas. Because they exploit shallow aquifers, the well may be susceptible to yield fluctuations and possible contamination from surface water, including sewage. Hand dug well construction generally requires the use of a well trained construction team, and the capital investment for equipment such as concrete ring moulds, heavy lifting equipment, well shaft formwork, motorized de-watering pumps, and fuel can be large for people in developing countries. Construction of hand dug wells can be dangerous due to collapse of the well bore, falling objects and asphyxiation, including from dewatering pump exhaust fumes.\n\nThe [Woodingdean Water Well](https:\/\/en.wikipedia.org\/wiki\/Woodingdean_Water_Well \"Woodingdean Water Well\"), hand-dug between 1858 and 1862, is the deepest hand-dug well at 392 metres (1,285 ft).[\\[15\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-15) The [Big Well](https:\/\/en.wikipedia.org\/wiki\/Big_Well \"Big Well\") in [Greensburg, Kansas](https:\/\/en.wikipedia.org\/wiki\/Greensburg,_Kansas \"Greensburg, Kansas\"), is billed as the world's largest hand-dug well, at 109 feet (33 m) deep and 32 feet (9.8 m) in diameter. However, the *Well of Joseph* in the [Cairo Citadel](https:\/\/en.wikipedia.org\/wiki\/Cairo_Citadel \"Cairo Citadel\") at 280 feet (85 m) deep and the [Pozzo di San Patrizio](https:\/\/en.wikipedia.org\/wiki\/Pozzo_di_San_Patrizio \"Pozzo di San Patrizio\") (St. Patrick's Well) built in 1527 in [Orvieto, Italy](https:\/\/en.wikipedia.org\/wiki\/Orvieto \"Orvieto\"), at 61 metres (200 ft) deep by 13 metres (43 ft) wide[\\[16\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-16) are both larger by volume.\n\n### Driven wells\n\\[[edit](https:\/\/en.wikipedia.org\/w\/index.php?title=Well&action=edit&section=4 \"Edit section: Driven wells\")\\]\n\nDriven wells may be very simply created in unconsolidated material with a *well hole structure*, which consists of a hardened drive point and a screen (perforated pipe). The point is simply hammered into the ground, usually with a tripod and *driver*, with pipe sections added as needed. A driver is a weighted pipe that slides over the pipe being driven and is repeatedly dropped on it. When [groundwater](https:\/\/en.wikipedia.org\/wiki\/Groundwater \"Groundwater\") is encountered, the well is washed of sediment and a pump installed.[\\[17\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-17)\n\n### Drilled wells\n\\[[edit](https:\/\/en.wikipedia.org\/w\/index.php?title=Well&action=edit&section=5 \"Edit section: Drilled wells\")\\]\n\nFurther information: [Well drilling](https:\/\/en.wikipedia.org\/wiki\/Well_drilling \"Well drilling\") and [Borewells in India](https:\/\/en.wikipedia.org\/wiki\/Borewells_in_India \"Borewells in India\")\n\nDrilled wells are constructed using various types of drilling machines, such as top-head rotary, table rotary, or cable tool, which all use drilling stems that rotate to cut into the formation, thus the term \"drilling.\"\n\nDrilled wells can be excavated by simple hand drilling methods (augering, sludging, jetting, driving, hand percussion) or machine drilling (auger, rotary, percussion, down the hole hammer). Deep rock rotary drilling method is most common. Rotary can be used in 90% of formation types (consolidated).\n\nDrilled wells can get water from a much deeper level than dug wells can − often down to several hundred metres.[\\[18\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-18)\n\nDrilled wells with electric pumps are used throughout the world, typically in rural or sparsely populated areas, though many urban areas are supplied partly by municipal wells. Most shallow well drilling machines are mounted on large trucks, trailers, or tracked vehicle carriages. Water wells typically range from 3 to 18 metres (10–60 ft) deep, but in some areas it can go deeper than 900 metres (3,000 ft).\\[*[citation needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Citation_needed \"Wikipedia:Citation needed\")*\\]\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/5\/59\/Well_spudder_8606.jpg\/250px-Well_spudder_8606.jpg)](https:\/\/en.wikipedia.org\/wiki\/File:Well_spudder_8606.jpg)\n\n[Cable tool](https:\/\/en.wikipedia.org\/wiki\/Drilling_rig#Cable_tool_drilling \"Drilling rig\") water well drilling rig in [Kimball, West Virginia](https:\/\/en.wikipedia.org\/wiki\/Kimball,_West_Virginia \"Kimball, West Virginia\")\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/e\/e2\/AquaBellaPickard-v.jpg\/250px-AquaBellaPickard-v.jpg)](https:\/\/en.wikipedia.org\/wiki\/File:AquaBellaPickard-v.jpg)\n\nIsraeli geologist [Leo Picard](https:\/\/en.wikipedia.org\/wiki\/Leo_Picard \"Leo Picard\") (white shirt) inspects a drilled water well outside the depopulated Palestinian village of [Bayt Naqquba](https:\/\/en.wikipedia.org\/wiki\/Bayt_Naqquba \"Bayt Naqquba\")\n\nRotary drilling machines use a segmented steel drilling string, typically made up of 3m (10ft), 6 m (20 ft) to 8m (26ft) sections of steel tubing that are threaded together, with a [bit](https:\/\/en.wikipedia.org\/wiki\/Drill_bit#Well_drilling_bits \"Drill bit\") or other drilling device at the bottom end. Some rotary drilling machines are designed to install (by driving or drilling) a steel casing into the well in conjunction with the drilling of the actual bore hole. Air and\/or water is used as a circulation fluid to displace cuttings and cool bits during the drilling. Another form of rotary-style drilling, termed *mud rotary*, makes use of a specially made mud, or drilling fluid, which is constantly being altered during the drill so that it can consistently create enough hydraulic pressure to hold the side walls of the bore hole open, regardless of the presence of a casing in the well. Typically, boreholes drilled into solid rock are not cased until after the drilling process is completed, regardless of the machinery used.\n\nThe oldest form of drilling machinery is the [cable tool](https:\/\/en.wikipedia.org\/wiki\/Drilling_rig#Cable_tool_drilling \"Drilling rig\"), still used today. Specifically designed to raise and lower a bit into the bore hole, the *spudding* of the drill causes the bit to be raised and dropped onto the bottom of the hole, and the design of the cable causes the bit to twist at approximately 1⁄4 revolution per drop, thereby creating a drilling action. Unlike rotary drilling, cable tool drilling requires the drilling action to be stopped so that the bore hole can be bailed or emptied of drilled cuttings. Cable tool drilling rigs are rare as they tend to be 10x slower to drill through materials compared to similar diameter rotary air or rotary mud equipped rigs.\n\nDrilled wells are usually cased with a factory-made pipe, typically [steel](https:\/\/en.wikipedia.org\/wiki\/Steel \"Steel\") (in air rotary or cable tool drilling) or [plastic](https:\/\/en.wikipedia.org\/wiki\/Plastic \"Plastic\")\/[PVC](https:\/\/en.wikipedia.org\/wiki\/PVC \"PVC\") (in mud rotary wells, also present in wells drilled into solid rock). The casing is constructed by welding, either chemically or thermally, segments of casing together. If the casing is installed during the drilling, most drills will drive the casing into the ground as the bore hole advances, while some newer machines will actually allow for the casing to be rotated and drilled into the formation in a similar manner as the bit advancing just below. PVC or plastic is typically solvent welded and then lowered into the drilled well, vertically stacked with their ends nested and either glued or splined together. The sections of casing are usually 6 metres (20 ft) or more in length, and 4 to 12 in (10 to 30 cm) in diameter, depending on the intended use of the well and local groundwater conditions.\n\nSurface contamination of wells in the United States is typically controlled by the use of a *surface seal*. A large hole is drilled to a predetermined depth or to a confining formation (clay or bedrock, for example), and then a smaller hole for the well is completed from that point forward. The well is typically cased from the surface down into the smaller hole with a casing that is the same diameter as that hole. The annular space between the large bore hole and the smaller casing is filled with [bentonite clay](https:\/\/en.wikipedia.org\/wiki\/Bentonite_clay \"Bentonite clay\"), concrete, or other sealant material. This creates an impermeable seal from the surface to the next confining layer that keeps contaminants from traveling down the outer sidewalls of the casing or borehole and into the [aquifer](https:\/\/en.wikipedia.org\/wiki\/Aquifer \"Aquifer\"). In addition, wells are typically capped with either an engineered well cap or seal that vents air through a screen into the well, but keeps insects, small animals, and unauthorized persons from accessing the well.\n\nAt the bottom of wells, based on formation, a screening device, filter pack, slotted casing, or open bore hole is left to allow the flow of water into the well. Constructed screens are typically used in unconsolidated formations (sands, gravels, etc.), allowing water and a percentage of the formation to pass through the screen. Allowing some material to pass through creates a large area filter out of the rest of the formation, as the amount of material present to pass into the well slowly decreases and is removed from the well. Rock wells are typically cased with a PVC liner\/casing and screen or slotted casing at the bottom, this is mostly present just to keep rocks from entering the pump assembly. Some wells use a *filter pack* method, where an undersized screen or slotted casing is placed inside the well and a filter medium is packed around the screen, between the screen and the borehole or casing. This allows the water to be filtered of unwanted materials before entering the well and pumping zone.\n\n- [![An automated water well system powered by a jet-pump](https:\/\/upload.wikimedia.org\/wikipedia\/en\/thumb\/8\/8e\/Jet-pump_System.svg\/120px-Jet-pump_System.svg.png)](https:\/\/en.wikipedia.org\/wiki\/File:Jet-pump_System.svg \"An automated water well system powered by a jet-pump\")\n  An automated water well system powered by a jet-pump\n- [![An automated water well system powered by a submersible pump](https:\/\/upload.wikimedia.org\/wikipedia\/en\/thumb\/2\/28\/Submersible-pump_System.svg\/120px-Submersible-pump_System.svg.png)](https:\/\/en.wikipedia.org\/wiki\/File:Submersible-pump_System.svg \"An automated water well system powered by a submersible pump\")\n  An automated water well system powered by a submersible pump\n- [![A water well system with a cistern](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/f\/f1\/Water_System_With_Cistern.svg\/120px-Water_System_With_Cistern.svg.png)](https:\/\/en.wikipedia.org\/wiki\/File:Water_System_With_Cistern.svg \"A water well system with a cistern\")\n  A water well system with a cistern\n- [![A water well system with a pressurized cistern](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/8\/8e\/Water_System_With_Pressurized_Cistern.svg\/120px-Water_System_With_Pressurized_Cistern.svg.png)](https:\/\/en.wikipedia.org\/wiki\/File:Water_System_With_Pressurized_Cistern.svg \"A water well system with a pressurized cistern\")\n  A water well system with a pressurized cistern\n- [![A section of a stainless steel screen well](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/5\/5d\/Screen_tube.JPG\/120px-Screen_tube.JPG)](https:\/\/en.wikipedia.org\/wiki\/File:Screen_tube.JPG \"A section of a stainless steel screen well\")\n  A section of a stainless steel screen well\n\n## Classification\n\\[[edit](https:\/\/en.wikipedia.org\/w\/index.php?title=Well&action=edit&section=6 \"Edit section: Classification\")\\]\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/c\/c2\/Water_well_types_wiki.svg\/500px-Water_well_types_wiki.svg.png)](https:\/\/en.wikipedia.org\/wiki\/File:Water_well_types_wiki.svg)\n\nWater well types\n\nThere are two broad classes of drilled-well types, based on the type of [aquifer](https:\/\/en.wikipedia.org\/wiki\/Aquifer \"Aquifer\") the well is in:\n\n- *Shallow* or *unconfined wells* are completed in the uppermost saturated aquifer at that location (the upper unconfined aquifer).\\[*[citation needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Citation_needed \"Wikipedia:Citation needed\")*\\]\n- *Deep* or *confined wells* are sunk through an impermeable stratum into an aquifer that is sandwiched between two impermeable strata (aquitards or aquicludes). The majority of deep aquifers are classified as artesian because the hydraulic head in a confined well is higher than the level of the top of the aquifer. If the hydraulic head in a confined well is higher than the land surface it is a \"flowing\" [artesian well](https:\/\/en.wikipedia.org\/wiki\/Artesian_well \"Artesian well\") (named after [Artois](https:\/\/en.wikipedia.org\/wiki\/Artois \"Artois\") in [France](https:\/\/en.wikipedia.org\/wiki\/France \"France\")).[\\[19\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-19)\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/7\/75\/Old-fashioned_well_in_Finland.JPG\/250px-Old-fashioned_well_in_Finland.JPG)](https:\/\/en.wikipedia.org\/wiki\/File:Old-fashioned_well_in_Finland.JPG)\n\nAn old-fashioned water well in the countryside of [Utajärvi](https:\/\/en.wikipedia.org\/wiki\/Utaj%C3%A4rvi \"Utajärvi\"), [Finland](https:\/\/en.wikipedia.org\/wiki\/Finland \"Finland\")\n\nA special type of water well may be constructed adjacent to freshwater lakes or streams. Commonly called a collector well but sometimes referred to by the trade name Ranney well or [Ranney collector](https:\/\/en.wikipedia.org\/wiki\/Ranney_collector \"Ranney collector\"), this type of well involves sinking a caisson vertically below the top of the aquifer and then advancing lateral collectors out of the caisson and beneath the surface water body. Pumping from within the caisson induces infiltration of water from the surface water body into the aquifer, where it is collected by the collector well laterals and conveyed into the caisson where it can be pumped to the ground surface.\\[*[citation needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Citation_needed \"Wikipedia:Citation needed\")*\\]\n\nTwo additional broad classes of well types may be distinguished, based on the use of the well:\n\n- *production* or *pumping wells*, are large diameter (greater than 15 cm in diameter) cased (metal, plastic, or concrete) water wells, constructed for extracting water from the aquifer by a [pump](https:\/\/en.wikipedia.org\/wiki\/Pump \"Pump\") (if the well is not [artesian](https:\/\/en.wikipedia.org\/wiki\/Artesian_aquifer \"Artesian aquifer\")).\\[*[citation needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Citation_needed \"Wikipedia:Citation needed\")*\\]\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/5\/5c\/Well_schematic.pdf\/page1-250px-Well_schematic.pdf.jpg)](https:\/\/en.wikipedia.org\/wiki\/File:Well_schematic.pdf)\n\nSchematic diagram of a groundwater monitoring well\n\n- *monitoring wells* or *[piezometers](https:\/\/en.wikipedia.org\/wiki\/Piezometer \"Piezometer\")*, are often smaller diameter wells used to monitor the hydraulic head or sample the groundwater for chemical constituents. Piezometers are monitoring wells completed over a very short section of aquifer. Monitoring wells can also be completed at multiple levels, allowing discrete samples or measurements to be made at different vertical elevations at the same map location.[\\[20\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-20)\n\nA water well constructed for pumping groundwater can be used passively as a monitoring well and a small diameter well can be pumped, but this distinction by use is common.\\[*[citation needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Citation_needed \"Wikipedia:Citation needed\")*\\]\n\n## Siting\n\\[[edit](https:\/\/en.wikipedia.org\/w\/index.php?title=Well&action=edit&section=7 \"Edit section: Siting\")\\]\n\nBefore excavation, information about the geology, water table depth, seasonal fluctuations, recharge area and rate should be found if possible. This work can be done by a [hydrogeologist](https:\/\/en.wikipedia.org\/wiki\/Hydrogeologist \"Hydrogeologist\"), or a groundwater surveyor using a variety of tools including electro-seismic surveying,[\\[21\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-21) any available information from nearby wells, geologic maps, and sometimes [geophysical imaging](https:\/\/en.wikipedia.org\/wiki\/Geophysical_imaging \"Geophysical imaging\"). These professionals provide advice that is almost as accurate a driller who has experience and knowledge of nearby wells\/bores and the most suitable drilling technique based on the expected target depth.\n\n## Contamination\n\\[[edit](https:\/\/en.wikipedia.org\/w\/index.php?title=Well&action=edit&section=8 \"Edit section: Contamination\")\\]\n\nFurther information: [Groundwater pollution](https:\/\/en.wikipedia.org\/wiki\/Groundwater_pollution \"Groundwater pollution\")\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/9\/9d\/Groundwater_Contamination_Latin_America_Sm.png\/250px-Groundwater_Contamination_Latin_America_Sm.png)](https:\/\/en.wikipedia.org\/wiki\/File:Groundwater_Contamination_Latin_America_Sm.png)\n\n[Waterborne diseases](https:\/\/en.wikipedia.org\/wiki\/Waterborne_diseases \"Waterborne diseases\") can be spread via a well which is contaminated with fecal pathogens from [pit latrines](https:\/\/en.wikipedia.org\/wiki\/Pit_latrine \"Pit latrine\").\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/b\/b4\/Cleaning_a_well_in_Yaounde.jpg\/250px-Cleaning_a_well_in_Yaounde.jpg)](https:\/\/en.wikipedia.org\/wiki\/File:Cleaning_a_well_in_Yaounde.jpg)\n\nMan cleaning a well in [Yaoundé](https:\/\/en.wikipedia.org\/wiki\/Yaound%C3%A9 \"Yaoundé\"), [Cameroon](https:\/\/en.wikipedia.org\/wiki\/Cameroon \"Cameroon\")\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/b\/b4\/Hand_water_pump_in_India_%283382861084%29.jpg\/250px-Hand_water_pump_in_India_%283382861084%29.jpg)](https:\/\/en.wikipedia.org\/wiki\/File:Hand_water_pump_in_India_\\(3382861084\\).jpg)\n\nHand pump to pump water from a well in a village near Chennai in India, where the well water might be polluted by nearby [pit latrines](https:\/\/en.wikipedia.org\/wiki\/Pit_latrine \"Pit latrine\").\n\nShallow pumping wells can often supply [drinking water](https:\/\/en.wikipedia.org\/wiki\/Drinking_water \"Drinking water\") at a very low cost. However, impurities from the surface easily reach shallow sources, which leads to a greater risk of contamination for these wells compared to deeper wells. Contaminated wells can lead to the spread of various [waterborne diseases](https:\/\/en.wikipedia.org\/wiki\/Waterborne_diseases \"Waterborne diseases\"). Dug and driven wells are relatively easy to contaminate; for instance, most dug wells are unreliable in the majority of the United States.[\\[22\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-CEH-CID-22) Some research has found that, in cold regions, changes in river flow and flooding caused by extreme rainfall or snowmelt can degrade well water quality.[\\[23\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-23)\n\n### Pathogens\n\\[[edit](https:\/\/en.wikipedia.org\/w\/index.php?title=Well&action=edit&section=9 \"Edit section: Pathogens\")\\]\n\nMost of the [bacteria](https:\/\/en.wikipedia.org\/wiki\/Bacteria \"Bacteria\"), [viruses](https:\/\/en.wikipedia.org\/wiki\/Viruses \"Viruses\"), [parasites](https:\/\/en.wikipedia.org\/wiki\/Parasite \"Parasite\"), and [fungi](https:\/\/en.wikipedia.org\/wiki\/Fungi \"Fungi\") that contaminate well water comes from [fecal material](https:\/\/en.wikipedia.org\/wiki\/Feces \"Feces\") from humans and other animals. Common bacterial contaminants include *[E. coli](https:\/\/en.wikipedia.org\/wiki\/E._coli \"E. coli\")*, *[Salmonella](https:\/\/en.wikipedia.org\/wiki\/Salmonella \"Salmonella\")*, *[Shigella](https:\/\/en.wikipedia.org\/wiki\/Shigella \"Shigella\")*, and *[Campylobacter jejuni](https:\/\/en.wikipedia.org\/wiki\/Campylobacter_jejuni \"Campylobacter jejuni\")*. Common viral contaminants include *[norovirus](https:\/\/en.wikipedia.org\/wiki\/Norovirus \"Norovirus\")*, *[sapovirus](https:\/\/en.wikipedia.org\/wiki\/Sapovirus \"Sapovirus\")*, *[rotavirus](https:\/\/en.wikipedia.org\/wiki\/Rotavirus \"Rotavirus\")*, [enteroviruses](https:\/\/en.wikipedia.org\/wiki\/Enterovirus \"Enterovirus\"), and [hepatitis A](https:\/\/en.wikipedia.org\/wiki\/Hepatitis_A \"Hepatitis A\") and [E](https:\/\/en.wikipedia.org\/wiki\/Hepatitis_E \"Hepatitis E\"). Parasites include *[Giardia lamblia](https:\/\/en.wikipedia.org\/wiki\/Giardia_lamblia \"Giardia lamblia\")*, *[Cryptosporidium](https:\/\/en.wikipedia.org\/wiki\/Cryptosporidium \"Cryptosporidium\")*, *[Cyclospora cayetanensis](https:\/\/en.wikipedia.org\/wiki\/Cyclospora_cayetanensis \"Cyclospora cayetanensis\")*, and [microsporidia](https:\/\/en.wikipedia.org\/wiki\/Microsporidia \"Microsporidia\").[\\[22\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-CEH-CID-22)\n\n### Chemical contamination\n\\[[edit](https:\/\/en.wikipedia.org\/w\/index.php?title=Well&action=edit&section=10 \"Edit section: Chemical contamination\")\\]\n\nChemical contamination is a common problem with groundwater.[\\[24\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-24) [Nitrates](https:\/\/en.wikipedia.org\/wiki\/Nitrate \"Nitrate\") from [sewage](https:\/\/en.wikipedia.org\/wiki\/Sewage \"Sewage\"), [sewage sludge](https:\/\/en.wikipedia.org\/wiki\/Sewage_sludge \"Sewage sludge\") or [fertilizer](https:\/\/en.wikipedia.org\/wiki\/Fertilizer \"Fertilizer\") are a particular problem for babies and young children. Pollutant chemicals include [pesticides](https:\/\/en.wikipedia.org\/wiki\/Pesticide \"Pesticide\") and [volatile organic compounds](https:\/\/en.wikipedia.org\/wiki\/Volatile_organic_compound \"Volatile organic compound\") from [gasoline](https:\/\/en.wikipedia.org\/wiki\/Gasoline \"Gasoline\"), [dry-cleaning](https:\/\/en.wikipedia.org\/wiki\/Dry-cleaning \"Dry-cleaning\"), the fuel additive [methyl tert-butyl ether](https:\/\/en.wikipedia.org\/wiki\/Methyl_tert-butyl_ether \"Methyl tert-butyl ether\") (MTBE), and [perchlorate](https:\/\/en.wikipedia.org\/wiki\/Perchlorate \"Perchlorate\") from rocket fuel, airbag inflators, and other artificial and natural sources.\\[*[citation needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Citation_needed \"Wikipedia:Citation needed\")*\\]\n\nSeveral minerals are also contaminants, including [lead](https:\/\/en.wikipedia.org\/wiki\/Lead \"Lead\") leached from brass fittings or old lead pipes, [chromium VI](https:\/\/en.wikipedia.org\/wiki\/Chromium_VI \"Chromium VI\") from electroplating and other sources, naturally occurring [arsenic](https:\/\/en.wikipedia.org\/wiki\/Arsenic \"Arsenic\"), [radon](https:\/\/en.wikipedia.org\/wiki\/Radon \"Radon\"), and [uranium](https:\/\/en.wikipedia.org\/wiki\/Uranium \"Uranium\")—all of which can cause cancer—and naturally occurring [fluoride](https:\/\/en.wikipedia.org\/wiki\/Fluoride \"Fluoride\"), which is desirable in low quantities to prevent [tooth decay](https:\/\/en.wikipedia.org\/wiki\/Tooth_decay \"Tooth decay\"), but can cause [dental fluorosis](https:\/\/en.wikipedia.org\/wiki\/Dental_fluorosis \"Dental fluorosis\") in higher concentrations.[\\[22\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-CEH-CID-22)\n\nSome chemicals are commonly present in water wells at levels that are not toxic, but can cause other problems. [Calcium](https:\/\/en.wikipedia.org\/wiki\/Calcium \"Calcium\") and [magnesium](https:\/\/en.wikipedia.org\/wiki\/Magnesium \"Magnesium\") cause what is known as [hard water](https:\/\/en.wikipedia.org\/wiki\/Hard_water \"Hard water\"), which can precipitate and clog pipes or burn out water heaters. [Iron](https:\/\/en.wikipedia.org\/wiki\/Iron \"Iron\") and [manganese](https:\/\/en.wikipedia.org\/wiki\/Manganese \"Manganese\") can appear as dark flecks that stain clothing and plumbing, and can promote the growth of [iron and manganese bacteria](https:\/\/en.wikipedia.org\/wiki\/Iron_bacteria \"Iron bacteria\") that can form slimy black colonies that clog pipes.[\\[22\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-CEH-CID-22)\n\n### Prevention\n\\[[edit](https:\/\/en.wikipedia.org\/w\/index.php?title=Well&action=edit&section=11 \"Edit section: Prevention\")\\]\n\nFurther information: [Onsite sewage facility](https:\/\/en.wikipedia.org\/wiki\/Onsite_sewage_facility \"Onsite sewage facility\")\n\nThe quality of the well water can be significantly increased by lining the well, sealing the well head, fitting a self-priming hand pump, constructing an apron, ensuring the area is kept clean and free from stagnant water and animals, moving sources of contamination ([pit latrines](https:\/\/en.wikipedia.org\/wiki\/Pit_latrine \"Pit latrine\"), garbage pits, [on-site sewer systems](https:\/\/en.wikipedia.org\/wiki\/Onsite_sewage_facility \"Onsite sewage facility\")) and carrying out hygiene education. The well should be cleaned with 1% chlorine solution after construction and periodically every 6 months.\\[*[citation needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Citation_needed \"Wikipedia:Citation needed\")*\\]\n\nWell holes should be covered to prevent loose debris, animals, animal excrement, and wind-blown foreign matter from falling into the hole and decomposing. The cover should be able to be in place at all times, including when drawing water from the well. A suspended roof over an open hole helps to some degree, but ideally the cover should be tight fitting and fully enclosing, with only a screened air vent.\\[*[citation needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Citation_needed \"Wikipedia:Citation needed\")*\\]\n\nMinimum distances and soil percolation requirements between sewage disposal sites and water wells need to be observed. Rules regarding the design and installation of private and municipal septic systems take all these factors into account so that nearby drinking water sources are protected.\n\nEducation of the general population in society also plays an important role in protecting drinking water.\\[*[citation needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Citation_needed \"Wikipedia:Citation needed\")*\\]\n\n### Mitigation\n\\[[edit](https:\/\/en.wikipedia.org\/w\/index.php?title=Well&action=edit&section=12 \"Edit section: Mitigation\")\\]\n\nCleanup of [contaminated groundwater](https:\/\/en.wikipedia.org\/wiki\/Contaminated_groundwater \"Contaminated groundwater\") tends to be very costly. Effective [remediation of groundwater](https:\/\/en.wikipedia.org\/wiki\/Groundwater_remediation \"Groundwater remediation\") is generally very difficult. Contamination of groundwater from surface and subsurface sources can usually be dramatically reduced by correctly centering the casing during construction and filling the casing [annulus](https:\/\/en.wikipedia.org\/wiki\/Annulus_\\(well\\) \"Annulus (well)\") with an appropriate sealing material. The sealing material (grout) should be placed from immediately above the production zone back to surface, because, in the absence of a correctly constructed casing seal, contaminated fluid can travel into the well through the casing annulus. Centering devices are important (usually one per length of casing or at maximum intervals of 9 m) to ensure that the grouted annular space is of even thickness.\\[*[citation needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Citation_needed \"Wikipedia:Citation needed\")*\\]\n\nUpon the construction of a new test well, it is considered best practice to invest in a complete battery of chemical and biological tests on the well water in question. Point-of-use treatment is available for individual properties and treatment plants are often constructed for municipal water supplies that suffer from contamination. Most of these treatment methods involve the [filtration](https:\/\/en.wikipedia.org\/wiki\/Filtration \"Filtration\") of the contaminants of concern, and additional protection may be garnered by installing well-casing screens only at depths where contamination is not present.\\[*[citation needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Citation_needed \"Wikipedia:Citation needed\")*\\]\n\nWellwater for personal use is often filtered with [reverse osmosis](https:\/\/en.wikipedia.org\/wiki\/Reverse_osmosis \"Reverse osmosis\") water processors; this process can remove very small particles. A simple, effective way of killing microorganisms is to bring the water to a full boil for one to three minutes, depending on location. A household well contaminated by microorganisms can initially be treated by shock chlorination using bleach, generating concentrations hundreds of times greater than found in community water systems; however, this will not fix any structural problems that led to the contamination and generally requires some expertise and testing for effective application.[\\[22\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-CEH-CID-22)\n\nAfter the filtration process, it is common to implement an [ultraviolet](https:\/\/en.wikipedia.org\/wiki\/Ultraviolet_germicidal_irradiation \"Ultraviolet germicidal irradiation\") (UV) system to kill pathogens in the water. UV light affects the DNA of the pathogen by UV-C photons breaking through the cell wall. UV disinfection has been gaining popularity in the past decades as it is a chemical-free method of water treatment.[\\[25\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-25)\n\n## Environmental problems\n\\[[edit](https:\/\/en.wikipedia.org\/w\/index.php?title=Well&action=edit&section=13 \"Edit section: Environmental problems\")\\]\n\nA risk with the placement of water wells is [soil salination](https:\/\/en.wikipedia.org\/wiki\/Soil_salinity \"Soil salinity\") which occurs when the water table of the soil begins to drop and salt begins to accumulate as the soil begins to dry out.[\\[26\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-26) Another environmental problem that is very prevalent in water well drilling is the potential for methane to seep through.\n\n### Soil salination\n\\[[edit](https:\/\/en.wikipedia.org\/w\/index.php?title=Well&action=edit&section=14 \"Edit section: Soil salination\")\\]\n\nThe potential for soil salination is a large risk when choosing the placement of water wells. Soil salination is caused when the water table of the soil drops over time and salt begins to accumulate. In turn, the increased amount of salt begins to dry the soil out. The increased level of salt in the soil can result in the degradation of soil and can be very harmful to vegetation.\\[*[citation needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Citation_needed \"Wikipedia:Citation needed\")*\\]\n\n### Methane\n\\[[edit](https:\/\/en.wikipedia.org\/w\/index.php?title=Well&action=edit&section=15 \"Edit section: Methane\")\\]\n\n[Methane](https:\/\/en.wikipedia.org\/wiki\/Methane \"Methane\"), an asphyxiant, is a chemical compound that is the main component of natural gas. When methane is introduced into a confined space, it displaces oxygen, reducing oxygen concentration to a level low enough to pose a threat to humans and other aerobic organisms but still high enough for a risk of [spontaneous](https:\/\/en.wikipedia.org\/wiki\/Spontaneous_combustion \"Spontaneous combustion\") or externally caused explosion. This potential for explosion is what poses such a danger in regards to the drilling and placement of water wells.\\[*[citation needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Citation_needed \"Wikipedia:Citation needed\")*\\]\n\nLow levels of methane in drinking water are not considered toxic. When methane seeps into a water supply, it is commonly referred to as \"methane migration\". This can be caused by old natural gas wells near water well systems becoming abandoned and no longer monitored.\\[*[citation needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Citation_needed \"Wikipedia:Citation needed\")*\\]\n\nLately,\\[*[when?](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Manual_of_Style\/Dates_and_numbers#Chronological_items \"Wikipedia:Manual of Style\/Dates and numbers\")*\\] however, the described wells\/pumps are no longer very efficient and can be replaced by either [handpumps](https:\/\/en.wikipedia.org\/wiki\/Handpump \"Handpump\") or [treadle pumps](https:\/\/en.wikipedia.org\/wiki\/Treadle_pump \"Treadle pump\"). Another alternative is the use of self-dug wells, electrical deep-well pumps (for higher depths). [Appropriate technology](https:\/\/en.wikipedia.org\/wiki\/Appropriate_technology \"Appropriate technology\") organizations as [Practical Action](https:\/\/en.wikipedia.org\/wiki\/Practical_Action \"Practical Action\") are now\\[*[when?](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Manual_of_Style\/Dates_and_numbers#Chronological_items \"Wikipedia:Manual of Style\/Dates and numbers\")*\\] supplying information on how to build\/set-up ([DIY](https:\/\/en.wikipedia.org\/wiki\/Do_it_yourself \"Do it yourself\")) handpumps and [treadle pumps](https:\/\/en.wikipedia.org\/wiki\/Treadle_pump \"Treadle pump\") in practice.[\\[27\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-27)[\\[28\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-28)\n\n### PFAS\/PFOS Fire fighting foam\n\\[[edit](https:\/\/en.wikipedia.org\/w\/index.php?title=Well&action=edit&section=16 \"Edit section: PFAS\/PFOS Fire fighting foam\")\\]\n\n**Per- and polyfluoroalkyl substances** (**[PFAS](https:\/\/en.wikipedia.org\/wiki\/Per-_and_polyfluoroalkyl_substances \"Per- and polyfluoroalkyl substances\")** or **PFASs**) are a group of synthetic [organofluorine](https:\/\/en.wikipedia.org\/wiki\/Organofluorine_chemistry \"Organofluorine chemistry\") [chemical compounds](https:\/\/en.wikipedia.org\/wiki\/Chemical_compound \"Chemical compound\") that have multiple [fluorine](https:\/\/en.wikipedia.org\/wiki\/Fluorine \"Fluorine\") atoms attached to an [alkyl](https:\/\/en.wikipedia.org\/wiki\/Alkyl \"Alkyl\") chain. PFAS are a group of \"forever chemicals\" that spread very quickly and very far in ground water polluting it permanently. Water wells near certain airports where any foam fire fighting or training activities occurred up to 2010 are likely to be contaminated by PFAS.\n\n## Water security\n\\[[edit](https:\/\/en.wikipedia.org\/w\/index.php?title=Well&action=edit&section=17 \"Edit section: Water security\")\\]\n\nA study concluded that of ~39 million groundwater wells 9-20% are at [high risk of running dry](https:\/\/en.wikipedia.org\/wiki\/Water_security \"Water security\") if local groundwater levels decline by less than five meters, or – as with many areas and possibly more than half of major [aquifers](https:\/\/en.wikipedia.org\/wiki\/Aquifer \"Aquifer\")[\\[29\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-29) – continue to decline.[\\[30\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-30)[\\[31\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-31)\\[*[further explanation needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Please_clarify \"Wikipedia:Please clarify\")*\\]\n\n## Society and culture\n\\[[edit](https:\/\/en.wikipedia.org\/w\/index.php?title=Well&action=edit&section=18 \"Edit section: Society and culture\")\\]\n\nSee also: [Wells in the Bible](https:\/\/en.wikipedia.org\/wiki\/Wells_in_the_Bible \"Wells in the Bible\")\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/6\/6a\/22-alimenti%2C_acqua_dolce%2CTaccuino_Sanitatis%2C_Casanatense_418.jpg\/250px-22-alimenti%2C_acqua_dolce%2CTaccuino_Sanitatis%2C_Casanatense_418.jpg)](https:\/\/en.wikipedia.org\/wiki\/File:22-alimenti,_acqua_dolce,Taccuino_Sanitatis,_Casanatense_418.jpg)\n\nWater use, [Tacuinum Sanitatis](https:\/\/en.wikipedia.org\/wiki\/Tacuinum_Sanitatis \"Tacuinum Sanitatis\"), [Biblioteca Casanatense](https:\/\/en.wikipedia.org\/wiki\/Biblioteca_Casanatense \"Biblioteca Casanatense\") (14th century)\n\n[Springs](https:\/\/en.wikipedia.org\/wiki\/Spring_\\(hydrology\\) \"Spring (hydrology)\") and wells have had [cultural significance](https:\/\/en.wikipedia.org\/wiki\/Cultural_significance \"Cultural significance\") since [prehistoric](https:\/\/en.wikipedia.org\/wiki\/Prehistoric \"Prehistoric\") times, leading to the foundation of towns such as [Wells](https:\/\/en.wikipedia.org\/wiki\/Wells,_Somerset \"Wells, Somerset\") and [Bath](https:\/\/en.wikipedia.org\/wiki\/Bath,_Somerset \"Bath, Somerset\") in [Somerset](https:\/\/en.wikipedia.org\/wiki\/Somerset \"Somerset\"). Interest in health benefits led to the growth of [spa towns](https:\/\/en.wikipedia.org\/wiki\/Spa_town \"Spa town\") including many with *wells* in their name, examples being [Llandrindod Wells](https:\/\/en.wikipedia.org\/wiki\/Llandrindod_Wells \"Llandrindod Wells\") and [Royal Tunbridge Wells](https:\/\/en.wikipedia.org\/wiki\/Royal_Tunbridge_Wells \"Royal Tunbridge Wells\").[\\[32\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-Burr-32)\n\n[Eratosthenes](https:\/\/en.wikipedia.org\/wiki\/Eratosthenes \"Eratosthenes\") is sometimes claimed to have used a well in his calculation of the [Earth's circumference](https:\/\/en.wikipedia.org\/wiki\/Earth%27s_circumference \"Earth's circumference\"); however, this is just a simplification used in a shorter explanation of [Cleomedes](https:\/\/en.wikipedia.org\/wiki\/Cleomedes \"Cleomedes\"), since Eratosthenes had used a more elaborate and precise method.[\\[33\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-russo273277-33)\n\nMany incidents in the [Bible](https:\/\/en.wikipedia.org\/wiki\/Bible \"Bible\") take place around wells, such as the finding of a wife for [Isaac](https:\/\/en.wikipedia.org\/wiki\/Isaac \"Isaac\") in [Genesis](https:\/\/en.wikipedia.org\/wiki\/Book_of_Genesis \"Book of Genesis\") and [Jesus](https:\/\/en.wikipedia.org\/wiki\/Jesus \"Jesus\")'s talk with the Samaritan woman in the [Gospels](https:\/\/en.wikipedia.org\/wiki\/Gospels \"Gospels\").[\\[34\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-34)\n\n## A simple model for water well recovery\n\\[[edit](https:\/\/en.wikipedia.org\/w\/index.php?title=Well&action=edit&section=19 \"Edit section: A simple model for water well recovery\")\\]\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/5\/57\/Well_Recovery_diagram.jpg\/250px-Well_Recovery_diagram.jpg)](https:\/\/en.wikipedia.org\/wiki\/File:Well_Recovery_diagram.jpg)\n\nDiagram of a water well partially filled to level *z* with the top of the aquifer at *zT*\n\nFor a well with impermeable walls, the water in the well is resupplied from the bottom of the well. The rate at which water flows into the well will depend on the pressure difference between the ground water at the well bottom and the well water at the well bottom. The pressure of a column of water of height *z* will be equal to the weight of the water in the column divided by the cross-sectional area of the column, so the pressure of the ground water a distance *zT* below the top of the water table will be:\n\nP\n\ng\n\n\\=\n\nρ\n\ng\n\nz\n\nT\n\n{\\\\displaystyle P\\_{g}=\\\\rho \\\\,g\\\\,z\\_{T}}\n\n![{\\\\displaystyle P\\_{g}=\\\\rho \\\\,g\\\\,z\\_{T}}](https:\/\/wikimedia.org\/api\/rest_v1\/media\/math\/render\/svg\/638cbf760d9b102d42a0fe61424cfbb84eb644ed)\n\nwhere *ρ* is the mass density of the water and *g* is the acceleration due to gravity. When the water in the well is below the water table level, the pressure at the bottom of the well due to the water in the well will be less than *Pg* and water will be forced into the well. Referring to the diagram, if *z* is the distance from the bottom of the well to the well water level and *zT* is the distance from the bottom of the well to the top of the water table, the pressure difference will be:\n\nΔ\n\nP\n\n\\=\n\nρ\n\ng\n\n(\n\nz\n\nT\n\n−\n\nz\n\n)\n\n{\\\\displaystyle \\\\Delta P=\\\\rho \\\\,g\\\\,(z\\_{T}-z)}\n\n![{\\\\displaystyle \\\\Delta P=\\\\rho \\\\,g\\\\,(z\\_{T}-z)}](https:\/\/wikimedia.org\/api\/rest_v1\/media\/math\/render\/svg\/311a95e84de02b5c6e319eedd8feb50ea181063e)\n\nApplying [Darcy's law](https:\/\/en.wikipedia.org\/wiki\/Darcy%27s_law \"Darcy's law\"), the volume rate (*F*) at which water is forced into the well will be proportional to this pressure difference:\n\nΔ\n\nP\n\n\\=\n\nR\n\nF\n\n{\\\\displaystyle \\\\Delta P=R\\\\,F}\n\n![{\\\\displaystyle \\\\Delta P=R\\\\,F}](https:\/\/wikimedia.org\/api\/rest_v1\/media\/math\/render\/svg\/5786632d6b2bb052677675191ea1e572c14aaa15)\n\nwhere *R* is the resistance to the flow, which depends on the well cross section, the pressure gradient at the bottom of the well, and the characteristics of the substrate at the well bottom. (e.g., porosity). The volume flow rate into the well can be written as a function of the rate of change of the well water level:\n\nF\n\n\\=\n\nA\n\nd\n\nz\n\nd\n\nt\n\n{\\\\displaystyle F=A{\\\\frac {dz}{dt}}}\n\n![{\\\\displaystyle F=A{\\\\frac {dz}{dt}}}](https:\/\/wikimedia.org\/api\/rest_v1\/media\/math\/render\/svg\/2a739564c0695861c243527e15701b5380b474c5)\n\nCombining the above three equations yields a simple differential equation in *z*:\n\nR\n\nA\n\nd\n\nz\n\nd\n\nt\n\n\\=\n\nρ\n\ng\n\n(\n\nz\n\nT\n\n−\n\nz\n\n)\n\n{\\\\displaystyle RA{\\\\frac {dz}{dt}}=\\\\rho g(z\\_{T}-z)}\n\n![{\\\\displaystyle RA{\\\\frac {dz}{dt}}=\\\\rho g(z\\_{T}-z)}](https:\/\/wikimedia.org\/api\/rest_v1\/media\/math\/render\/svg\/17afdd8ee77364f91732322618429ae09d2a4fe0)\n\nwhich may be solved:\n\nz\n\n\\=\n\nz\n\nT\n\n−\n\n(\n\nz\n\nT\n\n−\n\nz\n\n0\n\n)\n\ne\n\n−\n\nt\n\n\/\n\nτ\n\n{\\\\displaystyle z=z\\_{T}-(z\\_{T}-z\\_{0})e^{-t\/\\\\tau }}\n\n![{\\\\displaystyle z=z\\_{T}-(z\\_{T}-z\\_{0})e^{-t\/\\\\tau }}](https:\/\/wikimedia.org\/api\/rest_v1\/media\/math\/render\/svg\/16df3ea8a895dd6cd73a39111821a175b1c5d98d)\n\nwhere *z0* is the well water level at time *t=0* and *τ* is the well time constant:\n\nτ\n\n\\=\n\nR\n\nA\n\nρ\n\ng\n\n{\\\\displaystyle \\\\tau ={\\\\frac {RA}{\\\\rho g}}}\n\n![{\\\\displaystyle \\\\tau ={\\\\frac {RA}{\\\\rho g}}}](https:\/\/wikimedia.org\/api\/rest_v1\/media\/math\/render\/svg\/01cd2f59d9c030817d81d1c8ab981b070faa8d3b)\n\nNote that if *dz\/dt* for a depleted well can be measured, it will be equal to z T \/ τ {\\\\displaystyle z\\_{T}\/\\\\tau } ![{\\\\displaystyle z\\_{T}\/\\\\tau }](https:\/\/wikimedia.org\/api\/rest_v1\/media\/math\/render\/svg\/b72aa8e3c928e0d99f543788380c18fe540ac987) and the time constant τ can be calculated. According to the above model, it will take an infinite amount of time for a well to fully recover, but if we consider a well that is 99% recovered to be \"practically\" recovered, the time for a well to practically recover from a level at *z* will be:\n\nT\n\nr\n\n\\=\n\nτ\n\nln\n\n⁡\n\n(\n\n1\n\n−\n\nz\n\n\/\n\nz\n\nT\n\n1\n\n−\n\n0\\.99\n\n)\n\n{\\\\displaystyle T\\_{r}=\\\\tau \\\\ln \\\\left({\\\\frac {1-z\/z\\_{T}}{1-0.99}}\\\\right)}\n\n![{\\\\displaystyle T\\_{r}=\\\\tau \\\\ln \\\\left({\\\\frac {1-z\/z\\_{T}}{1-0.99}}\\\\right)}](https:\/\/wikimedia.org\/api\/rest_v1\/media\/math\/render\/svg\/3db7a070422bcbfe86695fa9ed06fb1261b8d06a)\n\nFor a well that is fully depleted (*z=0*) it would take a time of about *4\\.6 τ* to practically recover.\n\nThe above model does not take into account the depletion of the aquifer due to the pumping which lowered the well water level (See [aquifer test](https:\/\/en.wikipedia.org\/wiki\/Aquifer_test \"Aquifer test\") and [groundwater flow equation](https:\/\/en.wikipedia.org\/wiki\/Groundwater_flow_equation \"Groundwater flow equation\")). Also, practical wells may have impermeable walls only up to, but not including the bedrock, which will give a larger surface area for water to enter the well.[\\[35\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-Humboldt-35)[\\[36\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-Inspectapedia-36)\n\n## Similar and related water structures\n\\[[edit](https:\/\/en.wikipedia.org\/w\/index.php?title=Well&action=edit&section=20 \"Edit section: Similar and related water structures\")\\]\n\n- Types of ancient wells\n  - [Brick-lined well](https:\/\/en.wikipedia.org\/wiki\/Brick-lined_well \"Brick-lined well\")\n  - [Castle well](https:\/\/en.wikipedia.org\/wiki\/Castle_well \"Castle well\"), for use in the castle\n  - [Cistern](https:\/\/en.wikipedia.org\/wiki\/Cistern \"Cistern\"), ancient Greek\n  - [Stepwell](https:\/\/en.wikipedia.org\/wiki\/Stepwell \"Stepwell\"), ancient India\n\n- Modern construction techniques\n  - [Baptist well drilling](https:\/\/en.wikipedia.org\/wiki\/Baptist_well_drilling \"Baptist well drilling\"), simple technique\n  - [Rodriguez well](https:\/\/en.wikipedia.org\/wiki\/Rodriguez_well \"Rodriguez well\"), for harvesting drinking water in polar regions\n  - [Spring supply](https:\/\/en.wikipedia.org\/wiki\/Spring_supply \"Spring supply\"), piped water supply from the well\n\n- Uses\n  - [Holy well](https:\/\/en.wikipedia.org\/wiki\/Holy_well \"Holy well\"), sacred wells in various religions\n    - [Abraham's well](https:\/\/en.wikipedia.org\/wiki\/Abraham%27s_well \"Abraham's well\"), sacred well in Israel\n    - [Ghat](https:\/\/en.wikipedia.org\/wiki\/Ghat \"Ghat\"), sacred in Hinduism and Buddhism\n\n- - Drainage and irrigation\n    - [Drainage by wells](https:\/\/en.wikipedia.org\/wiki\/Drainage_by_wells \"Drainage by wells\")\n    - [Shadoof](https:\/\/en.wikipedia.org\/wiki\/Shadoof \"Shadoof\"), an irrigation tool that is used to lift water from a water source onto land or into another waterway or basin\n\n- - Washing\n    - [Lavoir](https:\/\/en.wikipedia.org\/wiki\/Lavoir \"Lavoir\"), public place for washing clothes.\n\n## See also\n\\[[edit](https:\/\/en.wikipedia.org\/w\/index.php?title=Well&action=edit&section=21 \"Edit section: See also\")\\]\n\n- [Fossil water](https:\/\/en.wikipedia.org\/wiki\/Fossil_water \"Fossil water\")\n\n- [History of water supply and sanitation](https:\/\/en.wikipedia.org\/wiki\/History_of_water_supply_and_sanitation \"History of water supply and sanitation\")\n\n- [Ancient water conservation techniques](https:\/\/en.wikipedia.org\/wiki\/Johad#Similar \"Johad\")\n\n- [Self-supply of water and sanitation](https:\/\/en.wikipedia.org\/wiki\/Self-supply_of_water_and_sanitation \"Self-supply of water and sanitation\")\n\n## References\n\\[[edit](https:\/\/en.wikipedia.org\/w\/index.php?title=Well&action=edit&section=22 \"Edit section: References\")\\]\n\n1. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-1)**\n   Peltenburg, Edgar (2012). \"East Mediterranean water wells of the 9th–7th millennium BC\". In Klimscha, Florian (ed.). *Wasserwirtschaftliche Innovationen im archäologischen Kontext. Von den prähistorischen Anfängen bis zu den Metropolen der Antike*. Rahden\/Westfalia: Leidorf. pp. 69–82\\.\n2. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-2)**\n   Galili, Ehud; Nir, Yaacov (1993). \"The submerged Pre-Pottery Neolithic water well of Atlit-Yam, northern Israel, and its palaeoenvironmental implications\". *The Holocene*. **3** (3): 265–270\\. [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[1993Holoc...3..265G](https:\/\/ui.adsabs.harvard.edu\/abs\/1993Holoc...3..265G). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1177\/095968369300300309](https:\/\/doi.org\/10.1177%2F095968369300300309). [S2CID](https:\/\/en.wikipedia.org\/wiki\/S2CID_\\(identifier\\) \"S2CID (identifier)\") [130032420](https:\/\/api.semanticscholar.org\/CorpusID:130032420).\n3. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-3)**\n   Rybníček, Michal; Kočár, Petr; Muigg, Bernhard; Peška, Jaroslav; Sedláček, Radko; Tegel, Willy; Kolář, Tomáš (2020). [\"World's oldest dendrochronologically dated archaeological wood construction\"](https:\/\/www.sciencedirect.com\/science\/article\/pii\/S0305440320300066). *Journal of Archaeological Science*. **115** 105082. [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[2020JArSc.115j5082R](https:\/\/ui.adsabs.harvard.edu\/abs\/2020JArSc.115j5082R). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1016\/j.jas.2020.105082](https:\/\/doi.org\/10.1016%2Fj.jas.2020.105082). [S2CID](https:\/\/en.wikipedia.org\/wiki\/S2CID_\\(identifier\\) \"S2CID (identifier)\") [213707193](https:\/\/api.semanticscholar.org\/CorpusID:213707193).\n4. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-4)**\n   [\"Kückhovener Brunnen – Dorfgemeinschaft Kückhoven E. V.\"](http:\/\/www.dorfgemeinschaft-kueckhoven.de\/unser-dorf\/kueckhovener-brunnen\/)\n   \n   \\[*[permanent dead link](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Link_rot \"Wikipedia:Link rot\")*\\]\n5. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-5)**\n   Tegel W, Elburg R, Hakelberg D, Stäuble H, Büntgen U (2012). [\"Early Neolithic Water Wells Reveal the World's Oldest Wood Architecture\"](https:\/\/www.ncbi.nlm.nih.gov\/pmc\/articles\/PMC3526582). *PLOS ONE*. **7** (12) e51374. [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[2012PLoSO...751374T](https:\/\/ui.adsabs.harvard.edu\/abs\/2012PLoSO...751374T). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1371\/journal.pone.0051374](https:\/\/doi.org\/10.1371%2Fjournal.pone.0051374). [PMC](https:\/\/en.wikipedia.org\/wiki\/PMC_\\(identifier\\) \"PMC (identifier)\") [3526582](https:\/\/www.ncbi.nlm.nih.gov\/pmc\/articles\/PMC3526582). [PMID](https:\/\/en.wikipedia.org\/wiki\/PMID_\\(identifier\\) \"PMID (identifier)\") [23284685](https:\/\/pubmed.ncbi.nlm.nih.gov\/23284685).\n6. ^ [***a***](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-Kuhn2004_6-0) [***b***](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-Kuhn2004_6-1)\n   Kuhn, Oliver (2004-06-30). [\"Ancient Chinese Drilling\"](https:\/\/csegrecorder.com\/articles\/view\/ancient-chinese-drilling). *Canadian Society of Exploration Geophysicists*. **29** (6).\n7. ^ [***a***](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-Chang2012_7-0) [***b***](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-Chang2012_7-1)\n   Chang, Mingteh (2012). *Forest Hydrology: An Introduction to Water and Forests* (3rd ed.). CRC Press (published November 1, 2012). p. 31. [ISBN](https:\/\/en.wikipedia.org\/wiki\/ISBN_\\(identifier\\) \"ISBN (identifier)\")\n   \n   [978-1-4398-7994-8](https:\/\/en.wikipedia.org\/wiki\/Special:BookSources\/978-1-4398-7994-8 \"Special:BookSources\/978-1-4398-7994-8\")\n   \n   .\n8. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-8)**\n   Koon, Wee Kek (July 25, 2015). [\"How the ancient Chinese looked after their drinking water\"](https:\/\/www.scmp.com\/magazines\/post-magazine\/article\/1843012\/how-ancient-chinese-looked-after-their-drinking-water). *South China Morning Post*.\n9. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-9)**\n   [\"Sakieh explication\/difference vs Sakia\"](http:\/\/www.britannica.com\/eb\/topic-518730\/sakia). *Britannica.com*. Retrieved 2011-12-19.\n10. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-10)**\n    [\"Sakia explication\"](http:\/\/www.britannica.com\/eb\/article-9001226\/sakia#271043.hook). *Britannica.com*. Retrieved 2011-12-19.\n11. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-11)**\n    [\"Stone Age wells found in Cyprus\"](https:\/\/news.bbc.co.uk\/2\/hi\/europe\/8118318.stm). *BBC News*.\n12. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-12)**\n    Ashkenazi, Eli (November 9, 2012). [\"Ancient Well Reveals Secrets of First Jezreel Valley Farmers\"](https:\/\/www.haaretz.com\/israel-news\/ancient-well-reveals-secrets-of-first-jezreel-valley-farmers-1.476288). *Haaretz*.\n13. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-ASTM_13-0)**\n    [\"ASTM International – Standards Worldwide\"](https:\/\/web.archive.org\/web\/20200801082953\/https:\/\/www.astm.org\/COMMIT\/D02\/to1899_index.html). *www.astm.org*. Archived from [the original](https:\/\/www.astm.org\/COMMIT\/D02\/to1899_index.html) on 2020-08-01. Retrieved 2019-02-01.\n14. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-EB1911_14-0)**\n    Joseph P. Riva Jr. and Gordon I. Atwater. [\"petroleum\"](http:\/\/www.britannica.com\/EBchecked\/topic\/454269\/petroleum). *[Encyclopædia Britannica](https:\/\/en.wikipedia.org\/wiki\/Encyclop%C3%A6dia_Britannica \"Encyclopædia Britannica\")*. Retrieved 2008-06-30.\n15. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-15)**\n    [\"Woodingdean Well\"](http:\/\/www.mybrightonandhove.org.uk\/page_id__6948_path__0p115p1224p597p.aspx). 2005. Retrieved 26 Jan 2010.\n16. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-16)**\n    [\"St. Patrick's Well\"](http:\/\/www.umbriatravel.com\/Orvieto\/en\/itineraries_Orvieto.asp). Umbriatravel.com. Retrieved 2011-12-19.\n    \n    \\[*[permanent dead link](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Link_rot \"Wikipedia:Link rot\")*\\]\n17. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-17)** [\"How I drill a Well.\"](https:\/\/books.google.com\/books?id=oiEDAAAAMBAJ&dq=popular+science+1930&pg=-PA77) *Popular Science*, April 1952, pp. 177–181.\n18. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-18)**\n    Association), NKBA (National Kitchen and Bath (2013-10-29). [*Kitchen & Bath Residential Construction and Systems*](https:\/\/books.google.com\/books?id=CVTjAQAAQBAJ&q=Drilled+wells+can+get+water+from+a+much+deeper+level+than+dug+wells+can%E2%80%94often+down+to+several+hundred+metres.&pg=PA178). John Wiley & Sons. [ISBN](https:\/\/en.wikipedia.org\/wiki\/ISBN_\\(identifier\\) \"ISBN (identifier)\")\n    \n    [978-1-118-71104-0](https:\/\/en.wikipedia.org\/wiki\/Special:BookSources\/978-1-118-71104-0 \"Special:BookSources\/978-1-118-71104-0\")\n    \n    .\n19. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-19)**\n    [\"Artesian Water and Artesian Wells \\| U.S. Geological Survey\"](https:\/\/www.usgs.gov\/water-science-school\/science\/artesian-water-and-artesian-wells). *www.usgs.gov*. 2018-10-09. Retrieved 2026-03-23.\n20. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-20)**\n    Arnold, L.R.; Flynn, J.L.; Paschke, S.S. (2009-10-20). [\"Design and installation of a groundwater monitoring-well network in the High Plains aquifer, Colorado\"](https:\/\/pubs.usgs.gov\/publication\/ds456). *USGS Report*. Data Series. U.S. Geological Survey: 5. [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[2009usgs.rept....5A](https:\/\/ui.adsabs.harvard.edu\/abs\/2009usgs.rept....5A). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.3133\/ds456](https:\/\/doi.org\/10.3133%2Fds456). Retrieved 27 May 2024.\n21. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-21)**\n    Du Preez, Michael. [\"ELECTRO-SEISMIC SURVEYS APPLIED TO MODDELING OF GROUNDWATER FLOW SYSTEMS\"](https:\/\/web.archive.org\/web\/20110531163202\/http:\/\/aquamap.co.nz\/uploads\/pdfs\/ELECTRO-SEISMIC%20SURVEYS%20APPLIED%20TO%20MODELING%20OF%20GROUNDWATER%20FLOW.pdf) (PDF). Bloemfontein, South Africa. Archived from [the original](http:\/\/aquamap.co.nz\/uploads\/pdfs\/ELECTRO-SEISMIC%20SURVEYS%20APPLIED%20TO%20MODELING%20OF%20GROUNDWATER%20FLOW.pdf) (PDF) on 31 May 2011. Retrieved 21 April 2011.\n22. ^ [***a***](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-CEH-CID_22-0) [***b***](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-CEH-CID_22-1) [***c***](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-CEH-CID_22-2) [***d***](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-CEH-CID_22-3) [***e***](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-CEH-CID_22-4)\n    Committee on Environmental Health; Committee on Infectious Diseases (2009). [\"Drinking water from private wells and risks to children\"](https:\/\/doi.org\/10.1542%2Fpeds.2009-0751). *[Pediatrics](https:\/\/en.wikipedia.org\/wiki\/Pediatrics_\\(journal\\) \"Pediatrics (journal)\")*. **123** (6): 1599–1605\\. [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1542\/peds.2009-0751](https:\/\/doi.org\/10.1542%2Fpeds.2009-0751). [PMID](https:\/\/en.wikipedia.org\/wiki\/PMID_\\(identifier\\) \"PMID (identifier)\") [19482772](https:\/\/pubmed.ncbi.nlm.nih.gov\/19482772).\n23. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-23)**\n    Wiebe, Andrew J.; Rudolph, David L.; Pasha, Ehsan; Brook, Jacqueline M.; Christie, Mike; Menkveld, Paul G. (2021). [\"Impacts of Event-Based Recharge on the Vulnerability of Public Supply Wells\"](https:\/\/doi.org\/10.3390%2Fsu13147695). *Sustainability*. **13** (14): 7695. [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[2021Sust...13.7695W](https:\/\/ui.adsabs.harvard.edu\/abs\/2021Sust...13.7695W). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.3390\/su13147695](https:\/\/doi.org\/10.3390%2Fsu13147695). [ISSN](https:\/\/en.wikipedia.org\/wiki\/ISSN_\\(identifier\\) \"ISSN (identifier)\") [2071-1050](https:\/\/search.worldcat.org\/issn\/2071-1050).\n24. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-24)**\n    Association, American Water Works (2003). [*Water Sources*](https:\/\/books.google.com\/books?id=iOIdnO03cgEC&q=Chemical+contamination+is+a+common+problem+with+groundwater&pg=PA141). American Water Works Association. [ISBN](https:\/\/en.wikipedia.org\/wiki\/ISBN_\\(identifier\\) \"ISBN (identifier)\")\n    \n    [978-1-58321-229-5](https:\/\/en.wikipedia.org\/wiki\/Special:BookSources\/978-1-58321-229-5 \"Special:BookSources\/978-1-58321-229-5\")\n    \n    .\n25. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-25)**\n    Meulemans, C. C. E. (1987-09-01). \"The Basic Principles of UV–Disinfection of Water\". *Ozone: Science & Engineering*. **9** (4): 299–313\\. [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[1987OzSE....9..299M](https:\/\/ui.adsabs.harvard.edu\/abs\/1987OzSE....9..299M). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1080\/01919518708552146](https:\/\/doi.org\/10.1080%2F01919518708552146). [ISSN](https:\/\/en.wikipedia.org\/wiki\/ISSN_\\(identifier\\) \"ISSN (identifier)\") [0191-9512](https:\/\/search.worldcat.org\/issn\/0191-9512).\n26. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-26)**\n    [\"Soil salination by placement of water wells mentioned in India\"](https:\/\/web.archive.org\/web\/20090522010539\/http:\/\/ngm.nationalgeographic.com\/2009\/06\/cheap-food\/bourne-text\/1). Ngm.nationalgeographic.com. 2002-10-17. Archived from [the original](http:\/\/ngm.nationalgeographic.com\/2009\/06\/cheap-food\/bourne-text\/1) on May 22, 2009. Retrieved 2011-12-19.\n27. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-27)**\n    [\"Practical Answers – Handpumps\"](http:\/\/practicalaction.org\/practicalanswers\/product_info.php?products_id=198). Practicalaction.org. Retrieved 2011-12-19.\n28. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-28)**\n    [\"Treadle pump\"](http:\/\/dev.practicalaction.org\/?id=appeal_nepalpump). Dev.practicalaction.org. Retrieved 2011-12-19.\n29. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-29)**\n    Famiglietti, James S.; Ferguson, Grant (23 April 2021). [\"The hidden crisis beneath our feet\"](https:\/\/www.science.org\/doi\/10.1126\/science.abh2867). *Science*. **372** (6540): 344–345\\. [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[2021Sci...372..344F](https:\/\/ui.adsabs.harvard.edu\/abs\/2021Sci...372..344F). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1126\/science.abh2867](https:\/\/doi.org\/10.1126%2Fscience.abh2867). [PMID](https:\/\/en.wikipedia.org\/wiki\/PMID_\\(identifier\\) \"PMID (identifier)\") [33888627](https:\/\/pubmed.ncbi.nlm.nih.gov\/33888627). [S2CID](https:\/\/en.wikipedia.org\/wiki\/S2CID_\\(identifier\\) \"S2CID (identifier)\") [233353241](https:\/\/api.semanticscholar.org\/CorpusID:233353241). Retrieved 10 May 2021.\n30. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-30)**\n    [\"The largest assessment of global groundwater wells finds many are at risk of drying up\"](https:\/\/www.sciencedaily.com\/releases\/2021\/04\/210423130101.htm). *ScienceDaily*. Retrieved 10 May 2021.\n31. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-31)**\n    Jasechko, Scott; Perrone, Debra (23 April 2021). [\"Global groundwater wells at risk of running dry\"](https:\/\/www.science.org\/doi\/10.1126\/science.abc2755). *Science*. **372** (6540): 418–421\\. [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[2021Sci...372..418J](https:\/\/ui.adsabs.harvard.edu\/abs\/2021Sci...372..418J). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1126\/science.abc2755](https:\/\/doi.org\/10.1126%2Fscience.abc2755). [ISSN](https:\/\/en.wikipedia.org\/wiki\/ISSN_\\(identifier\\) \"ISSN (identifier)\") [0036-8075](https:\/\/search.worldcat.org\/issn\/0036-8075). [PMID](https:\/\/en.wikipedia.org\/wiki\/PMID_\\(identifier\\) \"PMID (identifier)\") [33888642](https:\/\/pubmed.ncbi.nlm.nih.gov\/33888642). [S2CID](https:\/\/en.wikipedia.org\/wiki\/S2CID_\\(identifier\\) \"S2CID (identifier)\") [233353207](https:\/\/api.semanticscholar.org\/CorpusID:233353207). Retrieved 10 May 2021.\n32. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-Burr_32-0)**\n    Burr, Thomas Benge (1766). [*The History of Tunbridge Wells*](https:\/\/web.archive.org\/web\/20210131221739\/https:\/\/theweald.org\/d10.asp?BookId=burr000). London. Archived from [the original](http:\/\/theweald.org\/bk.asp?bookid=burr000) on 2021-01-31. Retrieved 2019-10-09.\n33. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-russo273277_33-0)**\n    [Russo, Lucio](https:\/\/en.wikipedia.org\/wiki\/Lucio_Russo \"Lucio Russo\") (2004). *The Forgotten Revolution*. Berlin: Springer. pp. 273–277\\.\n34. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-34)**\n    Bromiley, Geoffrey W. (1982), *International Standard Bible Encyclopedia: E-J*, Wm. B. Eerdmans Publishing, p. 955, [ISBN](https:\/\/en.wikipedia.org\/wiki\/ISBN_\\(identifier\\) \"ISBN (identifier)\")\n    \n    [978-0-8028-3782-0](https:\/\/en.wikipedia.org\/wiki\/Special:BookSources\/978-0-8028-3782-0 \"Special:BookSources\/978-0-8028-3782-0\")\n35. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-Humboldt_35-0)**\n    [\"Well Flow Equations\"](https:\/\/geology.humboldt.edu\/courses\/geology556\/556_handouts\/well_flow_equations.pdf) (PDF). Cal Poly Humboldt, Department of Geology. Retrieved June 13, 2022.\n36. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-Inspectapedia_36-0)**\n    [\"How Much Water Can the Well Deliver\"](https:\/\/inspectapedia.com\/water\/Well_Flow_Rate.php). Inspectapedia. Retrieved June 13, 2022.\n\n### Bibliography\n\\[[edit](https:\/\/en.wikipedia.org\/w\/index.php?title=Well&action=edit&section=23 \"Edit section: Bibliography\")\\]\n\n- Driscoll, F. (1986). *Groundwater and Wells*. [St. Paul](https:\/\/en.wikipedia.org\/wiki\/St._Paul,_MN \"St. Paul, MN\"): Johnson Filtration Systems. [ISBN](https:\/\/en.wikipedia.org\/wiki\/ISBN_\\(identifier\\) \"ISBN (identifier)\")\n  \n  [978-0-9616456-0-1](https:\/\/en.wikipedia.org\/wiki\/Special:BookSources\/978-0-9616456-0-1 \"Special:BookSources\/978-0-9616456-0-1\")\n  \n  .\n- Raymond Rowles (1995). *Drilling for Water* (2nd ed.). Avebury, Cranfield University. [ISBN](https:\/\/en.wikipedia.org\/wiki\/ISBN_\\(identifier\\) \"ISBN (identifier)\")\n  \n  [1-85628-984-2](https:\/\/en.wikipedia.org\/wiki\/Special:BookSources\/1-85628-984-2 \"Special:BookSources\/1-85628-984-2\")\n  \n  .\n\n## External links\n\\[[edit](https:\/\/en.wikipedia.org\/w\/index.php?title=Well&action=edit&section=24 \"Edit section: External links\")\\]\n\n[![Wikimedia Commons logo](https:\/\/upload.wikimedia.org\/wikipedia\/en\/thumb\/4\/4a\/Commons-logo.svg\/40px-Commons-logo.svg.png)](https:\/\/en.wikipedia.org\/wiki\/File:Commons-logo.svg)\n\nWikimedia Commons has media related to [Water wells](https:\/\/commons.wikimedia.org\/wiki\/Category:Water_wells \"commons:Category:Water wells\").\n\n[![Wikisource logo](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/4\/4c\/Wikisource-logo.svg\/40px-Wikisource-logo.svg.png)](https:\/\/en.wikipedia.org\/wiki\/File:Wikisource-logo.svg)\n\n[Wikisource](https:\/\/en.wikipedia.org\/wiki\/Wikisource \"Wikisource\") has the text of the [1911 *Encyclopædia Britannica*](https:\/\/en.wikipedia.org\/wiki\/Encyclop%C3%A6dia_Britannica_Eleventh_Edition \"Encyclopædia Britannica Eleventh Edition\") article \"[Well](https:\/\/en.wikisource.org\/wiki\/1911_Encyclop%C3%A6dia_Britannica\/Well \"wikisource:1911 Encyclopædia Britannica\/Well\")\".\n\n- [Sustainable Groundwater Development theme of the Rural Water Supply Network (RWSN)](http:\/\/www.rural-water-supply.net\/en\/sustainable-groundwater-management)\n- [Water Portal – Akvopedia](http:\/\/akvopedia.org\/wiki\/Water_Portal) [Archived](https:\/\/web.archive.org\/web\/20141018231204\/http:\/\/akvopedia.org\/wiki\/Water_Portal) 2014-10-18 at the [Wayback Machine](https:\/\/en.wikipedia.org\/wiki\/Wayback_Machine \"Wayback Machine\")\n- [Sustainable Sanitation and Water Management Toolbox](http:\/\/www.sswm.info\/)\n- [U.S. Centers for Disease Control and Prevention (CDC) Healthy Water – Water Wells](https:\/\/www.cdc.gov\/healthywater\/drinking\/private\/wells\/index.html) Site covering well basics, guidelines for proper siting and location of wells to avoid contamination, well testing, diseases related to wells, emergency well treatment and other topics.\n- [US Geological Survey – Ground water: Wells](https:\/\/ga.water.usgs.gov\/edu\/earthgwwells.html)\n- [US Geological Survey – Water Science Pictures Flowing Artesian Well](https:\/\/ga.water.usgs.gov\/edu\/gwartesian.html)\n- [Drilling wells 18 extremely useful questions and answers](https:\/\/www.euforaje.ro\/foraje-puturi\/)\n- [American Ground Water Trust](http:\/\/agwt.org\/)\n- [Lifewater International Technical Library](http:\/\/www.lifewater.org\/resources\/ground_water.html#GW) [Archived](https:\/\/web.archive.org\/web\/20130616030412\/http:\/\/www.lifewater.org\/resources\/ground_water.html#GW) 2013-06-16 at the [Wayback Machine](https:\/\/en.wikipedia.org\/wiki\/Wayback_Machine \"Wayback Machine\")\n- [Well Construction Technical Resources for NGOs](http:\/\/www.watersanitationhygiene.org\/References\/Technical%20Resources%20-%20Wells.htm)\n\n| [v](https:\/\/en.wikipedia.org\/wiki\/Template:Geotechnical_engineering \"Template:Geotechnical engineering\") [t](https:\/\/en.wikipedia.org\/wiki\/Template_talk:Geotechnical_engineering \"Template talk:Geotechnical engineering\") [e](https:\/\/en.wikipedia.org\/wiki\/Special:EditPage\/Template:Geotechnical_engineering \"Special:EditPage\/Template:Geotechnical engineering\")[Geotechnical engineering](https:\/\/en.wikipedia.org\/wiki\/Geotechnical_engineering \"Geotechnical engineering\") |   |\n|---|---|\n| [Offshore geotechnical engineering](https:\/\/en.wikipedia.org\/wiki\/Offshore_geotechnical_engineering \"Offshore geotechnical engineering\") |   |\n| [Investigation](https:\/\/en.wikipedia.org\/wiki\/Geotechnical_investigation \"Geotechnical investigation\")  and instrumentation |   |\n|   |   |\n| Field (*in situ*) | [![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/5\/5e\/Core_sample.svg\/20px-Core_sample.svg.png)](https:\/\/en.wikipedia.org\/wiki\/File:Core_sample.svg) [Core drill](https:\/\/en.wikipedia.org\/wiki\/Core_drill \"Core drill\") [![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/2\/28\/Cone_penetration_test.svg\/20px-Cone_penetration_test.svg.png)](https:\/\/en.wikipedia.org\/wiki\/File:Cone_penetration_test.svg) [Cone penetration test](https:\/\/en.wikipedia.org\/wiki\/Cone_penetration_test \"Cone penetration test\") [![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/1\/10\/Geo-electrical_sounding.svg\/20px-Geo-electrical_sounding.svg.png)](https:\/\/en.wikipedia.org\/wiki\/File:Geo-electrical_sounding.svg) [Geo-electrical sounding](https:\/\/en.wikipedia.org\/w\/index.php?title=Geo-electrical_sounding&action=edit&redlink=1 \"Geo-electrical sounding (page does not exist)\") [![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/7\/7b\/In_situ_permeameter_test.svg\/20px-In_situ_permeameter_test.svg.png)](https:\/\/en.wikipedia.org\/wiki\/File:In_situ_permeameter_test.svg) [Permeability test](https:\/\/en.wikipedia.org\/wiki\/Permeability_\\(Earth_sciences\\) \"Permeability (Earth sciences)\") [![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/a\/a2\/Load_test.svg\/20px-Load_test.svg.png)](https:\/\/en.wikipedia.org\/wiki\/File:Load_test.svg) [Load test](https:\/\/en.wikipedia.org\/wiki\/Load_test \"Load test\") [Static](https:\/\/en.wikipedia.org\/wiki\/Static_load_testing \"Static load testing\") [Dynamic](https:\/\/en.wikipedia.org\/wiki\/Dynamic_load_testing \"Dynamic load testing\") [Statnamic](https:\/\/en.wikipedia.org\/wiki\/Statnamic_load_test \"Statnamic load test\") [![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/f\/fe\/Pore_pressure_measurement.svg\/20px-Pore_pressure_measurement.svg.png)](https:\/\/en.wikipedia.org\/wiki\/File:Pore_pressure_measurement.svg) Pore pressure measurement [Piezometer](https:\/\/en.wikipedia.org\/wiki\/Piezometer \"Piezometer\") [Well](https:\/\/en.wikipedia.org\/wiki\/Well#Classification) [![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/5\/5d\/Ram_sounding.svg\/20px-Ram_sounding.svg.png)](https:\/\/en.wikipedia.org\/wiki\/File:Ram_sounding.svg) [Ram sounding](https:\/\/en.wikipedia.org\/w\/index.php?title=Ram_sounding&action=edit&redlink=1 \"Ram sounding (page does not exist)\") [![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/e\/e4\/Rock_control_drilling.svg\/20px-Rock_control_drilling.svg.png)](https:\/\/en.wikipedia.org\/wiki\/File:Rock_control_drilling.svg) [Rock control drilling](https:\/\/en.wikipedia.org\/w\/index.php?title=Rock_control_drilling&action=edit&redlink=1 \"Rock control drilling (page does not exist)\") [![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/8\/81\/Rotary_pressure_sounding.svg\/20px-Rotary_pressure_sounding.svg.png)](https:\/\/en.wikipedia.org\/wiki\/File:Rotary_pressure_sounding.svg) [Rotary-pressure sounding](https:\/\/en.wikipedia.org\/wiki\/Rotary-pressure_sounding \"Rotary-pressure sounding\") [![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/f\/f9\/Rotary_weight_sounding.svg\/20px-Rotary_weight_sounding.svg.png)](https:\/\/en.wikipedia.org\/wiki\/File:Rotary_weight_sounding.svg) [Rotary weight sounding](https:\/\/en.wikipedia.org\/w\/index.php?title=Rotary_weight_sounding&action=edit&redlink=1 \"Rotary weight sounding (page does not exist)\") [![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/0\/05\/Sample_series.svg\/20px-Sample_series.svg.png)](https:\/\/en.wikipedia.org\/wiki\/File:Sample_series.svg) [Sample series](https:\/\/en.wikipedia.org\/wiki\/Soil_test#Soil_testing \"Soil test\") [![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/7\/75\/Screw_plate_test.svg\/20px-Screw_plate_test.svg.png)](https:\/\/en.wikipedia.org\/wiki\/File:Screw_plate_test.svg) [Screw plate test](https:\/\/en.wikipedia.org\/w\/index.php?title=Screw_plate_test&action=edit&redlink=1 \"Screw plate test (page does not exist)\") [Deformation monitoring](https:\/\/en.wikipedia.org\/wiki\/Deformation_monitoring \"Deformation monitoring\") [![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/c\/c6\/Inclinometer.svg\/20px-Inclinometer.svg.png)](https:\/\/en.wikipedia.org\/wiki\/File:Inclinometer.svg) [Inclinometer](https:\/\/en.wikipedia.org\/wiki\/Inclinometer \"Inclinometer\") [![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/3\/35\/Settlement_recordings.svg\/20px-Settlement_recordings.svg.png)](https:\/\/en.wikipedia.org\/wiki\/File:Settlement_recordings.svg) [Settlement recordings](https:\/\/en.wikipedia.org\/wiki\/Soil_consolidation \"Soil consolidation\") [![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/a\/ae\/Shear_vane_test.svg\/20px-Shear_vane_test.svg.png)](https:\/\/en.wikipedia.org\/wiki\/File:Shear_vane_test.svg) [Shear vane test](https:\/\/en.wikipedia.org\/wiki\/Shear_vane_test \"Shear vane test\") [![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/d\/d4\/Simple_sounding.svg\/20px-Simple_sounding.svg.png)](https:\/\/en.wikipedia.org\/wiki\/File:Simple_sounding.svg) [Simple sounding](https:\/\/en.wikipedia.org\/w\/index.php?title=Simple_sounding&action=edit&redlink=1 \"Simple sounding (page does not exist)\") [![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/0\/0d\/Standard_penetration_test.svg\/20px-Standard_penetration_test.svg.png)](https:\/\/en.wikipedia.org\/wiki\/File:Standard_penetration_test.svg) [Standard penetration test](https:\/\/en.wikipedia.org\/wiki\/Standard_penetration_test \"Standard penetration test\") [![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/6\/60\/Total_sounding.svg\/20px-Total_sounding.svg.png)](https:\/\/en.wikipedia.org\/wiki\/File:Total_sounding.svg) [Total sounding](https:\/\/en.wikipedia.org\/wiki\/Total_sounding \"Total sounding\") [![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/7\/71\/Trial_pit.svg\/20px-Trial_pit.svg.png)](https:\/\/en.wikipedia.org\/wiki\/File:Trial_pit.svg) [Trial pit](https:\/\/en.wikipedia.org\/wiki\/Trial_pit \"Trial pit\") [![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/1\/14\/Visible_rock.svg\/20px-Visible_rock.svg.png)](https:\/\/en.wikipedia.org\/wiki\/File:Visible_rock.svg) [Visible bedrock](https:\/\/en.wikipedia.org\/wiki\/Bedrock \"Bedrock\") [Nuclear densometer test](https:\/\/en.wikipedia.org\/wiki\/Nuclear_densometer \"Nuclear densometer\") [Exploration geophysics](https:\/\/en.wikipedia.org\/wiki\/Exploration_geophysics \"Exploration geophysics\") [Crosshole sonic logging](https:\/\/en.wikipedia.org\/wiki\/Crosshole_sonic_logging \"Crosshole sonic logging\") [Pile integrity test](https:\/\/en.wikipedia.org\/wiki\/Pile_integrity_test \"Pile integrity test\") [Wave equation analysis](https:\/\/en.wikipedia.org\/wiki\/Wave_equation_analysis \"Wave equation analysis\") |\n| [Laboratory  testing](https:\/\/en.wikipedia.org\/wiki\/Soil_test \"Soil test\") | [Soil classification](https:\/\/en.wikipedia.org\/wiki\/Soil_classification \"Soil classification\") [Atterberg limits](https:\/\/en.wikipedia.org\/wiki\/Atterberg_limits \"Atterberg limits\") [California bearing ratio](https:\/\/en.wikipedia.org\/wiki\/California_bearing_ratio \"California bearing ratio\") [Direct shear test](https:\/\/en.wikipedia.org\/wiki\/Direct_shear_test \"Direct shear test\") [Hydrometer](https:\/\/en.wikipedia.org\/wiki\/Hydrometer \"Hydrometer\") [Proctor compaction test](https:\/\/en.wikipedia.org\/wiki\/Proctor_compaction_test \"Proctor compaction test\") [R-value](https:\/\/en.wikipedia.org\/wiki\/R-value_\\(soils\\) \"R-value (soils)\") [Sieve analysis](https:\/\/en.wikipedia.org\/wiki\/Sieve_analysis \"Sieve analysis\") [Triaxial shear test](https:\/\/en.wikipedia.org\/wiki\/Triaxial_shear_test \"Triaxial shear test\") [Oedometer test](https:\/\/en.wikipedia.org\/wiki\/Oedometer_test \"Oedometer test\") [Hydraulic conductivity tests](https:\/\/en.wikipedia.org\/wiki\/Hydraulic_conductivity#Experimental_approach \"Hydraulic conductivity\") [Water content tests](https:\/\/en.wikipedia.org\/wiki\/Water_content#Measurement \"Water content\") |\n| [Soil](https:\/\/en.wikipedia.org\/wiki\/Soil \"Soil\") |   |\n|   |   |\n| Types | [Clay](https:\/\/en.wikipedia.org\/wiki\/Clay \"Clay\") [Silt](https:\/\/en.wikipedia.org\/wiki\/Silt \"Silt\") [Sand](https:\/\/en.wikipedia.org\/wiki\/Sand \"Sand\") [Gravel](https:\/\/en.wikipedia.org\/wiki\/Gravel \"Gravel\") [Peat](https:\/\/en.wikipedia.org\/wiki\/Peat \"Peat\") [Loam](https:\/\/en.wikipedia.org\/wiki\/Loam \"Loam\") [Loess](https:\/\/en.wikipedia.org\/wiki\/Loess \"Loess\") |\n| Properties | [Hydraulic conductivity](https:\/\/en.wikipedia.org\/wiki\/Hydraulic_conductivity \"Hydraulic conductivity\") [Water content](https:\/\/en.wikipedia.org\/wiki\/Water_content \"Water content\") [Void ratio](https:\/\/en.wikipedia.org\/wiki\/Void_ratio \"Void ratio\") [Bulk density](https:\/\/en.wikipedia.org\/wiki\/Bulk_density \"Bulk density\") [Thixotropy](https:\/\/en.wikipedia.org\/wiki\/Thixotropy \"Thixotropy\") [Reynolds' dilatancy](https:\/\/en.wikipedia.org\/wiki\/Reynolds%27_dilatancy \"Reynolds' dilatancy\") [Angle of repose](https:\/\/en.wikipedia.org\/wiki\/Angle_of_repose \"Angle of repose\") [Friction angle](https:\/\/en.wikipedia.org\/wiki\/Friction#Angle_of_friction \"Friction\") [Cohesion](https:\/\/en.wikipedia.org\/wiki\/Cohesion_\\(geology\\) \"Cohesion (geology)\") [Porosity](https:\/\/en.wikipedia.org\/wiki\/Porosity \"Porosity\") [Permeability](https:\/\/en.wikipedia.org\/wiki\/Permeability_\\(earth_sciences\\) \"Permeability (earth sciences)\") [Specific storage](https:\/\/en.wikipedia.org\/wiki\/Specific_storage \"Specific storage\") [Shear strength](https:\/\/en.wikipedia.org\/wiki\/Shear_strength_\\(soil\\) \"Shear strength (soil)\") [Sensitivity](https:\/\/en.wikipedia.org\/wiki\/Soil_liquefaction \"Soil liquefaction\") |\n| Structures  ([Interaction](https:\/\/en.wikipedia.org\/wiki\/Soil-structure_interaction \"Soil-structure interaction\")) |   |\n|   |   |\n| Natural features | [Topography](https:\/\/en.wikipedia.org\/wiki\/Topography \"Topography\") [Vegetation](https:\/\/en.wikipedia.org\/wiki\/Vegetation \"Vegetation\") [Terrain](https:\/\/en.wikipedia.org\/wiki\/Terrain \"Terrain\") [Topsoil](https:\/\/en.wikipedia.org\/wiki\/Topsoil \"Topsoil\") [Water table](https:\/\/en.wikipedia.org\/wiki\/Water_table \"Water table\") [Bedrock](https:\/\/en.wikipedia.org\/wiki\/Bedrock \"Bedrock\") [Subgrade](https:\/\/en.wikipedia.org\/wiki\/Subgrade \"Subgrade\") [Subsoil](https:\/\/en.wikipedia.org\/wiki\/Subsoil \"Subsoil\") |\n| [Earthworks](https:\/\/en.wikipedia.org\/wiki\/Earthworks_\\(engineering\\) \"Earthworks (engineering)\") | Shoring structures [Retaining walls](https:\/\/en.wikipedia.org\/wiki\/Retaining_wall \"Retaining wall\") [Gabion](https:\/\/en.wikipedia.org\/wiki\/Gabion \"Gabion\") [Ground freezing](https:\/\/en.wikipedia.org\/wiki\/Ground_freezing \"Ground freezing\") [Mechanically stabilized earth](https:\/\/en.wikipedia.org\/wiki\/Mechanically_stabilized_earth \"Mechanically stabilized earth\") [Pressure grouting](https:\/\/en.wikipedia.org\/wiki\/Pressure_grouting \"Pressure grouting\") [Slurry wall](https:\/\/en.wikipedia.org\/wiki\/Slurry_wall \"Slurry wall\") [Soil nailing](https:\/\/en.wikipedia.org\/wiki\/Soil_nailing \"Soil nailing\") [Tieback](https:\/\/en.wikipedia.org\/wiki\/Tieback_\\(geotechnical\\) \"Tieback (geotechnical)\") [Land development](https:\/\/en.wikipedia.org\/wiki\/Land_development \"Land development\") [Landfill](https:\/\/en.wikipedia.org\/wiki\/Landfill \"Landfill\") [Excavation](https:\/\/en.wikipedia.org\/wiki\/Digging \"Digging\") [Trench](https:\/\/en.wikipedia.org\/wiki\/Trench \"Trench\") [Embankment](https:\/\/en.wikipedia.org\/wiki\/Embankment_\\(earthworks\\) \"Embankment (earthworks)\") [Cut](https:\/\/en.wikipedia.org\/wiki\/Cut_\\(earthworks\\) \"Cut (earthworks)\") [Causeway](https:\/\/en.wikipedia.org\/wiki\/Causeway \"Causeway\") [Terracing](https:\/\/en.wikipedia.org\/wiki\/Terrace_\\(earthworks\\) \"Terrace (earthworks)\") [Cut-and-cover](https:\/\/en.wikipedia.org\/wiki\/Tunnel#Cut-and-cover \"Tunnel\") [Cut and fill](https:\/\/en.wikipedia.org\/wiki\/Cut_and_fill \"Cut and fill\") [Fill dirt](https:\/\/en.wikipedia.org\/wiki\/Fill_dirt \"Fill dirt\") [Grading](https:\/\/en.wikipedia.org\/wiki\/Grading_\\(engineering\\) \"Grading (engineering)\") [Land reclamation](https:\/\/en.wikipedia.org\/wiki\/Land_reclamation \"Land reclamation\") [Track bed](https:\/\/en.wikipedia.org\/wiki\/Track_bed \"Track bed\") [Erosion control](https:\/\/en.wikipedia.org\/wiki\/Erosion_control \"Erosion control\") [Earth structure](https:\/\/en.wikipedia.org\/wiki\/Earth_structure \"Earth structure\") [Expanded clay aggregate](https:\/\/en.wikipedia.org\/wiki\/Expanded_clay_aggregate \"Expanded clay aggregate\") [Crushed stone](https:\/\/en.wikipedia.org\/wiki\/Crushed_stone \"Crushed stone\") [Geosynthetics](https:\/\/en.wikipedia.org\/wiki\/Geosynthetics \"Geosynthetics\") [Geotextile](https:\/\/en.wikipedia.org\/wiki\/Geotextile \"Geotextile\") [Geomembrane](https:\/\/en.wikipedia.org\/wiki\/Geomembrane \"Geomembrane\") [Geosynthetic clay liner](https:\/\/en.wikipedia.org\/wiki\/Geosynthetic_clay_liner \"Geosynthetic clay liner\") [Cellular confinement](https:\/\/en.wikipedia.org\/wiki\/Cellular_confinement \"Cellular confinement\") [Infiltration](https:\/\/en.wikipedia.org\/wiki\/Infiltration_\\(hydrology\\) \"Infiltration (hydrology)\") |\n| [Foundations](https:\/\/en.wikipedia.org\/wiki\/Foundation_\\(engineering\\) \"Foundation (engineering)\") | [Shallow](https:\/\/en.wikipedia.org\/wiki\/Shallow_foundation \"Shallow foundation\") [Deep](https:\/\/en.wikipedia.org\/wiki\/Deep_foundation \"Deep foundation\") |\n| [Mechanics](https:\/\/en.wikipedia.org\/wiki\/Soil_mechanics \"Soil mechanics\") |   |\n|   |   |\n| Forces | [Effective stress](https:\/\/en.wikipedia.org\/wiki\/Effective_stress \"Effective stress\") [Pore water pressure](https:\/\/en.wikipedia.org\/wiki\/Pore_water_pressure \"Pore water pressure\") [Lateral earth pressure](https:\/\/en.wikipedia.org\/wiki\/Lateral_earth_pressure \"Lateral earth pressure\") [Overburden pressure](https:\/\/en.wikipedia.org\/wiki\/Overburden_pressure \"Overburden pressure\") [Preconsolidation pressure](https:\/\/en.wikipedia.org\/wiki\/Preconsolidation_pressure \"Preconsolidation pressure\") |\n| Phenomena and problems | [Permafrost](https:\/\/en.wikipedia.org\/wiki\/Permafrost \"Permafrost\") [Frost heaving](https:\/\/en.wikipedia.org\/wiki\/Frost_heaving \"Frost heaving\") [Consolidation](https:\/\/en.wikipedia.org\/wiki\/Consolidation_\\(soil\\) \"Consolidation (soil)\") [Compaction](https:\/\/en.wikipedia.org\/wiki\/Soil_compaction \"Soil compaction\") [Earthquake](https:\/\/en.wikipedia.org\/wiki\/Earthquake \"Earthquake\") [Response spectrum](https:\/\/en.wikipedia.org\/wiki\/Response_spectrum \"Response spectrum\") [Seismic hazard](https:\/\/en.wikipedia.org\/wiki\/Seismic_hazard \"Seismic hazard\") [Shear wave](https:\/\/en.wikipedia.org\/wiki\/S_wave \"S wave\") [Landslide](https:\/\/en.wikipedia.org\/wiki\/Landslide \"Landslide\") analysis [Stability analysis](https:\/\/en.wikipedia.org\/wiki\/Slope_stability_analysis \"Slope stability analysis\") [Mitigation](https:\/\/en.wikipedia.org\/wiki\/Landslide_mitigation \"Landslide mitigation\") [Classification](https:\/\/en.wikipedia.org\/wiki\/Landslide_classification \"Landslide classification\") [Sliding criterion](https:\/\/en.wikipedia.org\/wiki\/Sliding_criterion_\\(geotechnical_engineering\\) \"Sliding criterion (geotechnical engineering)\") [Slab stabilisation](https:\/\/en.wikipedia.org\/wiki\/Road#Slab_stabilization \"Road\") [Bearing capacity](https:\/\/en.wikipedia.org\/wiki\/Bearing_capacity \"Bearing capacity\") [Stress distribution in soil](https:\/\/en.wikipedia.org\/wiki\/Stress_distribution_in_soil \"Stress distribution in soil\") |\n| [Numerical analysis  software](https:\/\/en.wikipedia.org\/wiki\/Software \"Software\") | [SEEP2D](https:\/\/en.wikipedia.org\/wiki\/SEEP2D \"SEEP2D\") [STABL](https:\/\/en.wikipedia.org\/w\/index.php?title=STABL&action=edit&redlink=1 \"STABL (page does not exist)\") [SVFlux](https:\/\/en.wikipedia.org\/wiki\/SVFlux \"SVFlux\") [SVSlope](https:\/\/en.wikipedia.org\/wiki\/SVSlope \"SVSlope\") [UTEXAS](https:\/\/en.wikipedia.org\/wiki\/UTEXAS \"UTEXAS\") [Plaxis](https:\/\/en.wikipedia.org\/wiki\/Plaxis \"Plaxis\") |\n| [Related fields](https:\/\/en.wikipedia.org\/wiki\/Geoprofessions \"Geoprofessions\") | [Geology](https:\/\/en.wikipedia.org\/wiki\/Geology \"Geology\") [Geochemistry](https:\/\/en.wikipedia.org\/wiki\/Geochemistry \"Geochemistry\") [Petrology](https:\/\/en.wikipedia.org\/wiki\/Petrology \"Petrology\") [Earthquake engineering](https:\/\/en.wikipedia.org\/wiki\/Earthquake_engineering \"Earthquake engineering\") [Geomorphology](https:\/\/en.wikipedia.org\/wiki\/Geomorphology \"Geomorphology\") [Soil science](https:\/\/en.wikipedia.org\/wiki\/Soil_science \"Soil science\") [Hydrology](https:\/\/en.wikipedia.org\/wiki\/Hydrology \"Hydrology\") [Hydrogeology](https:\/\/en.wikipedia.org\/wiki\/Hydrogeology \"Hydrogeology\") [Biogeography](https:\/\/en.wikipedia.org\/wiki\/Biogeography \"Biogeography\") [Earth materials](https:\/\/en.wikipedia.org\/wiki\/Earth_materials \"Earth materials\") [Archaeology](https:\/\/en.wikipedia.org\/wiki\/Archaeology \"Archaeology\") [Agricultural science](https:\/\/en.wikipedia.org\/wiki\/Agricultural_science \"Agricultural science\") [Agrology](https:\/\/en.wikipedia.org\/wiki\/Agrology \"Agrology\") |\n\n| [v](https:\/\/en.wikipedia.org\/wiki\/Template:Man-made_and_man-related_subterranea \"Template:Man-made and man-related subterranea\") [t](https:\/\/en.wikipedia.org\/wiki\/Template_talk:Man-made_and_man-related_subterranea \"Template talk:Man-made and man-related subterranea\") [e](https:\/\/en.wikipedia.org\/wiki\/Special:EditPage\/Template:Man-made_and_man-related_subterranea \"Special:EditPage\/Template:Man-made and man-related subterranea\")Man-made and man-related [subterranea](https:\/\/en.wikipedia.org\/wiki\/Subterranea_\\(geography\\) \"Subterranea (geography)\") |   |\n|---|---|\n| Natural features | [Cave](https:\/\/en.wikipedia.org\/wiki\/Cave \"Cave\") [Cenote](https:\/\/en.wikipedia.org\/wiki\/Cenote \"Cenote\") [Grotto](https:\/\/en.wikipedia.org\/wiki\/Grotto \"Grotto\") [Sinkhole](https:\/\/en.wikipedia.org\/wiki\/Sinkhole \"Sinkhole\") |\n| Civilian features | [Bank vault](https:\/\/en.wikipedia.org\/wiki\/Bank_vault \"Bank vault\") [Basement](https:\/\/en.wikipedia.org\/wiki\/Basement \"Basement\") [Burial vault (tomb)](https:\/\/en.wikipedia.org\/wiki\/Burial_vault_\\(tomb\\) \"Burial vault (tomb)\") [Borehole](https:\/\/en.wikipedia.org\/wiki\/Borehole \"Borehole\") [Catacombs](https:\/\/en.wikipedia.org\/wiki\/Catacombs \"Catacombs\") [Dungeon](https:\/\/en.wikipedia.org\/wiki\/Dungeon \"Dungeon\") [Dugout (shelter)](https:\/\/en.wikipedia.org\/wiki\/Dugout_\\(shelter\\) \"Dugout (shelter)\") [Dry well](https:\/\/en.wikipedia.org\/wiki\/Dry_well \"Dry well\") [Earth shelter](https:\/\/en.wikipedia.org\/wiki\/Earth_shelter \"Earth shelter\") [Erdstall](https:\/\/en.wikipedia.org\/wiki\/Erdstall \"Erdstall\") [Fogou](https:\/\/en.wikipedia.org\/wiki\/Fogou \"Fogou\") [Hypogeum](https:\/\/en.wikipedia.org\/wiki\/Hypogeum \"Hypogeum\") [Manhole](https:\/\/en.wikipedia.org\/wiki\/Manhole \"Manhole\") [Rapid transit](https:\/\/en.wikipedia.org\/wiki\/Rapid_transit \"Rapid transit\") [Rock-cut tomb](https:\/\/en.wikipedia.org\/wiki\/Rock-cut_tomb \"Rock-cut tomb\") [Root cellar](https:\/\/en.wikipedia.org\/wiki\/Root_cellar \"Root cellar\") [Tunnel](https:\/\/en.wikipedia.org\/wiki\/Tunnel \"Tunnel\") [Utility vault](https:\/\/en.wikipedia.org\/wiki\/Utility_vault \"Utility vault\") [Underground city](https:\/\/en.wikipedia.org\/wiki\/Underground_city \"Underground city\") [Well]() [Wine cave](https:\/\/en.wikipedia.org\/wiki\/Wine_cave \"Wine cave\") [Secret passage](https:\/\/en.wikipedia.org\/wiki\/Secret_passage \"Secret passage\") [Semi-basement](https:\/\/en.wikipedia.org\/wiki\/Semi-basement \"Semi-basement\") [Stepwell](https:\/\/en.wikipedia.org\/wiki\/Stepwell \"Stepwell\") [Storm cellar](https:\/\/en.wikipedia.org\/wiki\/Storm_cellar \"Storm cellar\") [Smuggling tunnel](https:\/\/en.wikipedia.org\/wiki\/Smuggling_tunnel \"Smuggling tunnel\") [Ventilation shaft](https:\/\/en.wikipedia.org\/wiki\/Ventilation_shaft \"Ventilation shaft\") |\n| Military features | [Air raid shelter](https:\/\/en.wikipedia.org\/wiki\/Air_raid_shelter \"Air raid shelter\") [Bunker](https:\/\/en.wikipedia.org\/wiki\/Bunker \"Bunker\") [Blast shelter](https:\/\/en.wikipedia.org\/wiki\/Blast_shelter \"Blast shelter\") [Casemate](https:\/\/en.wikipedia.org\/wiki\/Casemate \"Casemate\") [Fallout shelter](https:\/\/en.wikipedia.org\/wiki\/Fallout_shelter \"Fallout shelter\") [Missile launch facility](https:\/\/en.wikipedia.org\/wiki\/Missile_launch_facility \"Missile launch facility\") (silo) [Scallywag bunker](https:\/\/en.wikipedia.org\/wiki\/Scallywag_bunker \"Scallywag bunker\") [Underground base](https:\/\/en.wikipedia.org\/wiki\/Underground_base \"Underground base\") [Underground hangar](https:\/\/en.wikipedia.org\/wiki\/Underground_hangar \"Underground hangar\") [Spider hole](https:\/\/en.wikipedia.org\/wiki\/Spider_hole \"Spider hole\") |\n| [Mining](https:\/\/en.wikipedia.org\/wiki\/Mining \"Mining\"), [quarrying](https:\/\/en.wikipedia.org\/wiki\/Quarry \"Quarry\"), and [underground construction](https:\/\/en.wikipedia.org\/wiki\/Underground_construction \"Underground construction\") | [Rock-cut architecture](https:\/\/en.wikipedia.org\/wiki\/Rock-cut_architecture \"Rock-cut architecture\") [Subsurface utility engineering](https:\/\/en.wikipedia.org\/wiki\/Subsurface_utility_engineering \"Subsurface utility engineering\") [Tunnel construction](https:\/\/en.wikipedia.org\/wiki\/Tunnel_construction \"Tunnel construction\") [Underground mine ventilation](https:\/\/en.wikipedia.org\/wiki\/Underground_mine_ventilation \"Underground mine ventilation\") [Underground hard-rock mining](https:\/\/en.wikipedia.org\/wiki\/Underground_hard-rock_mining \"Underground hard-rock mining\") [Underground soft-rock mining](https:\/\/en.wikipedia.org\/wiki\/Underground_soft-rock_mining \"Underground soft-rock mining\") |\n| Related topics | [Cave dweller](https:\/\/en.wikipedia.org\/wiki\/Cave_dweller \"Cave dweller\") [Caves of Maastricht](https:\/\/en.wikipedia.org\/wiki\/Caves_of_Maastricht \"Caves of Maastricht\") [Civil defense](https:\/\/en.wikipedia.org\/wiki\/Civil_defense \"Civil defense\") [Coober Pedy](https:\/\/en.wikipedia.org\/wiki\/Coober_Pedy \"Coober Pedy\") [Houston tunnel system](https:\/\/en.wikipedia.org\/wiki\/Houston_tunnel_system \"Houston tunnel system\") [Kőbánya cellar system](https:\/\/en.wikipedia.org\/wiki\/K%C5%91b%C3%A1nya_cellar_system \"Kőbánya cellar system\") [Tunnel warfare](https:\/\/en.wikipedia.org\/wiki\/Tunnel_warfare \"Tunnel warfare\") [Tunnel network](https:\/\/en.wikipedia.org\/wiki\/Tunnel_network \"Tunnel network\") [Trench warfare](https:\/\/en.wikipedia.org\/wiki\/Trench_warfare \"Trench warfare\") [Underground living](https:\/\/en.wikipedia.org\/wiki\/Underground_living \"Underground living\") [Underground City (Beijing)](https:\/\/en.wikipedia.org\/wiki\/Underground_City_\\(Beijing\\) \"Underground City (Beijing)\") [Underground City, Montreal](https:\/\/en.wikipedia.org\/wiki\/Underground_City,_Montreal \"Underground City, Montreal\") [Mine exploration](https:\/\/en.wikipedia.org\/wiki\/Mine_exploration \"Mine exploration\") [Mines of Paris](https:\/\/en.wikipedia.org\/wiki\/Mines_of_Paris \"Mines of Paris\") [Mole people](https:\/\/en.wikipedia.org\/wiki\/Mole_people \"Mole people\") [Naples underground geothermal zone](https:\/\/en.wikipedia.org\/wiki\/Naples_underground_geothermal_zone \"Naples underground geothermal zone\") [Sapping](https:\/\/en.wikipedia.org\/wiki\/Sapping \"Sapping\") [Subterranean London](https:\/\/en.wikipedia.org\/wiki\/Subterranean_London \"Subterranean London\") [Subterranean Toledo](https:\/\/en.wikipedia.org\/wiki\/Subterranean_Toledo \"Subterranean Toledo\") [Subterranean warfare](https:\/\/en.wikipedia.org\/wiki\/Subterranean_warfare \"Subterranean warfare\") [Subterranean fiction](https:\/\/en.wikipedia.org\/wiki\/Subterranean_fiction \"Subterranean fiction\") |\n| Earth shelters US | [Bill Gates' house](https:\/\/en.wikipedia.org\/wiki\/Bill_Gates%27_house \"Bill Gates' house\") [Forestiere Underground Gardens](https:\/\/en.wikipedia.org\/wiki\/Forestiere_Underground_Gardens \"Forestiere Underground Gardens\") [Underground House Colorado](https:\/\/en.wikipedia.org\/wiki\/Underground_House_Colorado \"Underground House Colorado\") [Underground House Las Vegas](https:\/\/en.wikipedia.org\/wiki\/Underground_House_Las_Vegas \"Underground House Las Vegas\") [Underground World Home](https:\/\/en.wikipedia.org\/wiki\/Underground_World_Home \"Underground World Home\") |\n| Earth shelters UK | [Underhill, Holme](https:\/\/en.wikipedia.org\/wiki\/Underhill,_Holme \"Underhill, Holme\") [Hockerton Housing Project](https:\/\/en.wikipedia.org\/wiki\/Hockerton_Housing_Project \"Hockerton Housing Project\") [Malator](https:\/\/en.wikipedia.org\/wiki\/Malator \"Malator\") |\n| Earth shelters Australia | [Coober Pedy](https:\/\/en.wikipedia.org\/wiki\/Coober_Pedy \"Coober Pedy\") [Lightning Ridge](https:\/\/en.wikipedia.org\/wiki\/Lightning_Ridge,_New_South_Wales \"Lightning Ridge, New South Wales\") |\n\n| [Authority control databases](https:\/\/en.wikipedia.org\/wiki\/Help:Authority_control \"Help:Authority control\") [![Edit this at Wikidata](https:\/\/upload.wikimedia.org\/wikipedia\/en\/thumb\/8\/8a\/OOjs_UI_icon_edit-ltr-progressive.svg\/20px-OOjs_UI_icon_edit-ltr-progressive.svg.png)](https:\/\/www.wikidata.org\/wiki\/Q43483#identifiers \"Edit this at Wikidata\") |   |\n|---|---|\n| International | [GND](https:\/\/d-nb.info\/gnd\/4008491-7) |\n| National | [United States](https:\/\/id.loc.gov\/authorities\/sh85146057) [France](https:\/\/catalogue.bnf.fr\/ark:\/12148\/cb119759000) [BnF data](https:\/\/data.bnf.fr\/ark:\/12148\/cb119759000) [Japan](https:\/\/id.ndl.go.jp\/auth\/ndlna\/00563888) [Czech Republic](https:\/\/aleph.nkp.cz\/F\/?func=find-c&local_base=aut&ccl_term=ica=ph116306&CON_LNG=ENG) [Spain](https:\/\/datos.bne.es\/resource\/XX524606) [Latvia](https:\/\/kopkatalogs.lv\/F?func=direct&local_base=lnc10&doc_number=000082718&P_CON_LNG=ENG) [Poland](https:\/\/dbn.bn.org.pl\/descriptor-details\/9810545826905606) [Israel](https:\/\/www.nli.org.il\/en\/authorities\/987007553637505171) |\n| Other | [Yale LUX](https:\/\/lux.collections.yale.edu\/view\/concept\/9c201eec-4906-497e-8c9a-3749b416d797) |\n\n![](https:\/\/en.wikipedia.org\/wiki\/Special:CentralAutoLogin\/start?useformat=desktop&type=1x1&usesul3=1)\n\nRetrieved from \"<https:\/\/en.wikipedia.org\/w\/index.php?title=Well&oldid=1348155091>\"\n\n[Categories](https:\/\/en.wikipedia.org\/wiki\/Help:Category \"Help:Category\"):\n\n- [Water wells](https:\/\/en.wikipedia.org\/wiki\/Category:Water_wells \"Category:Water wells\")\n- [Archaeological features](https:\/\/en.wikipedia.org\/wiki\/Category:Archaeological_features \"Category:Archaeological features\")\n- [Bodies of water](https:\/\/en.wikipedia.org\/wiki\/Category:Bodies_of_water \"Category:Bodies of water\")\n- [Water supply infrastructure](https:\/\/en.wikipedia.org\/wiki\/Category:Water_supply_infrastructure \"Category:Water supply infrastructure\")\n- [In situ geotechnical investigations](https:\/\/en.wikipedia.org\/wiki\/Category:In_situ_geotechnical_investigations \"Category:In situ geotechnical investigations\")\n\nHidden categories:\n\n- [All articles with dead external links](https:\/\/en.wikipedia.org\/wiki\/Category:All_articles_with_dead_external_links \"Category:All articles with dead external links\")\n- [Articles with dead external links from August 2025](https:\/\/en.wikipedia.org\/wiki\/Category:Articles_with_dead_external_links_from_August_2025 \"Category:Articles with dead external links from August 2025\")\n- [Articles with permanently dead external links](https:\/\/en.wikipedia.org\/wiki\/Category:Articles_with_permanently_dead_external_links \"Category:Articles with permanently dead external links\")\n- [Articles with short description](https:\/\/en.wikipedia.org\/wiki\/Category:Articles_with_short_description \"Category:Articles with short description\")\n- [Short description is different from Wikidata](https:\/\/en.wikipedia.org\/wiki\/Category:Short_description_is_different_from_Wikidata \"Category:Short description is different from Wikidata\")\n- [All articles with unsourced statements](https:\/\/en.wikipedia.org\/wiki\/Category:All_articles_with_unsourced_statements \"Category:All articles with unsourced statements\")\n- [Articles with unsourced statements from April 2021](https:\/\/en.wikipedia.org\/wiki\/Category:Articles_with_unsourced_statements_from_April_2021 \"Category:Articles with unsourced statements from April 2021\")\n- [Articles with unsourced statements from February 2013](https:\/\/en.wikipedia.org\/wiki\/Category:Articles_with_unsourced_statements_from_February_2013 \"Category:Articles with unsourced statements from February 2013\")\n- [Articles with unsourced statements from May 2016](https:\/\/en.wikipedia.org\/wiki\/Category:Articles_with_unsourced_statements_from_May_2016 \"Category:Articles with unsourced statements from May 2016\")\n- [Articles with unsourced statements from January 2016](https:\/\/en.wikipedia.org\/wiki\/Category:Articles_with_unsourced_statements_from_January_2016 \"Category:Articles with unsourced statements from January 2016\")\n- [All articles with vague or ambiguous time](https:\/\/en.wikipedia.org\/wiki\/Category:All_articles_with_vague_or_ambiguous_time \"Category:All articles with vague or ambiguous time\")\n- [Vague or ambiguous time from May 2016](https:\/\/en.wikipedia.org\/wiki\/Category:Vague_or_ambiguous_time_from_May_2016 \"Category:Vague or ambiguous time from May 2016\")\n- [Wikipedia articles needing clarification from May 2021](https:\/\/en.wikipedia.org\/wiki\/Category:Wikipedia_articles_needing_clarification_from_May_2021 \"Category:Wikipedia articles needing clarification from May 2021\")\n- [Commons category link is on Wikidata](https:\/\/en.wikipedia.org\/wiki\/Category:Commons_category_link_is_on_Wikidata \"Category:Commons category link is on Wikidata\")\n- [Webarchive template wayback links](https:\/\/en.wikipedia.org\/wiki\/Category:Webarchive_template_wayback_links \"Category:Webarchive template wayback links\")\n\n- This page was last edited on 11 April 2026, at 01:17 (UTC).\n- Text is available under the [Creative Commons Attribution-ShareAlike 4.0 License](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Text_of_the_Creative_Commons_Attribution-ShareAlike_4.0_International_License \"Wikipedia:Text of the Creative Commons Attribution-ShareAlike 4.0 International License\"); additional terms may apply. By using this site, you agree to the [Terms of Use](https:\/\/foundation.wikimedia.org\/wiki\/Special:MyLanguage\/Policy:Terms_of_Use \"foundation:Special:MyLanguage\/Policy:Terms of Use\") and [Privacy Policy](https:\/\/foundation.wikimedia.org\/wiki\/Special:MyLanguage\/Policy:Privacy_policy \"foundation:Special:MyLanguage\/Policy:Privacy policy\"). Wikipedia® is a registered trademark of the [Wikimedia Foundation, Inc.](https:\/\/wikimediafoundation.org\/), a non-profit organization.\n\n- [Privacy policy](https:\/\/foundation.wikimedia.org\/wiki\/Special:MyLanguage\/Policy:Privacy_policy)\n- [About Wikipedia](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:About)\n- [Disclaimers](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:General_disclaimer)\n- [Contact Wikipedia](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Contact_us)\n- [Legal & safety contacts](https:\/\/foundation.wikimedia.org\/wiki\/Special:MyLanguage\/Legal:Wikimedia_Foundation_Legal_and_Safety_Contact_Information)\n- [Code of Conduct](https:\/\/foundation.wikimedia.org\/wiki\/Special:MyLanguage\/Policy:Universal_Code_of_Conduct)\n- [Developers](https:\/\/developer.wikimedia.org\/)\n- [Statistics](https:\/\/stats.wikimedia.org\/#\/en.wikipedia.org)\n- [Cookie statement](https:\/\/foundation.wikimedia.org\/wiki\/Special:MyLanguage\/Policy:Cookie_statement)\n- [Mobile view](https:\/\/en.wikipedia.org\/w\/index.php?title=Well&mobileaction=toggle_view_mobile)\n\n- [![Wikimedia Foundation](https:\/\/en.wikipedia.org\/static\/images\/footer\/wikimedia.svg)](https:\/\/www.wikimedia.org\/)\n- [![Powered by MediaWiki](https:\/\/en.wikipedia.org\/w\/resources\/assets\/mediawiki_compact.svg)](https:\/\/www.mediawiki.org\/)\n\nSearch\n\nToggle the table of contents\n\nWell\n\n123 languages\n\n[Add topic](https:\/\/en.wikipedia.org\/wiki\/Well)","attrs_readable_markdown":"\"Village pump\" redirects here. For the set of Wikipedia discussion pages, see [Wikipedia:Village pump](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Village_pump \"Wikipedia:Village pump\").\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/0\/01\/Faryab-_village_dug_well.JPG\/250px-Faryab-_village_dug_well.JPG)](https:\/\/en.wikipedia.org\/wiki\/File:Faryab-_village_dug_well.JPG)\n\nA dug well in a village in [Faryab Province](https:\/\/en.wikipedia.org\/wiki\/Faryab_Province \"Faryab Province\"), [Afghanistan](https:\/\/en.wikipedia.org\/wiki\/Afghanistan \"Afghanistan\")\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/0\/02\/Well-cistern.jpg\/250px-Well-cistern.jpg)](https:\/\/en.wikipedia.org\/wiki\/File:Well-cistern.jpg)\n\nThe difference between a well and a [cistern](https:\/\/en.wikipedia.org\/wiki\/Cistern \"Cistern\") is in the source of the water: a cistern collects [rainwater](https:\/\/en.wikipedia.org\/wiki\/Rainwater \"Rainwater\") whereas a well draws from [groundwater](https:\/\/en.wikipedia.org\/wiki\/Groundwater \"Groundwater\").\n\nA **well** is an excavation or structure created on the earth by [digging](https:\/\/en.wikipedia.org\/wiki\/Digging \"Digging\"), driving, or [drilling](https:\/\/en.wikipedia.org\/wiki\/Drilling \"Drilling\") to access [liquid](https:\/\/en.wikipedia.org\/wiki\/Liquid \"Liquid\") resources, usually [water](https:\/\/en.wikipedia.org\/wiki\/Water \"Water\"). The oldest and most common kind of well is a water well, to access [groundwater](https:\/\/en.wikipedia.org\/wiki\/Groundwater \"Groundwater\") in underground [aquifers](https:\/\/en.wikipedia.org\/wiki\/Aquifer \"Aquifer\"). The well water is drawn up by a [pump](https:\/\/en.wikipedia.org\/wiki\/Pump \"Pump\"), or using containers, such as [buckets](https:\/\/en.wikipedia.org\/wiki\/Bucket \"Bucket\") that are raised mechanically or by hand. Water can also be [injected back into the aquifer](https:\/\/en.wikipedia.org\/wiki\/Aquifer_storage_and_recovery \"Aquifer storage and recovery\") through the well. Wells were first constructed at least eight thousand years ago and historically vary in construction from a sediment of a dry watercourse to the [qanats](https:\/\/en.wikipedia.org\/wiki\/Qanat \"Qanat\") of Iran, and the [stepwells](https:\/\/en.wikipedia.org\/wiki\/Stepwell \"Stepwell\") and [sakiehs](https:\/\/en.wikipedia.org\/wiki\/Sakia \"Sakia\") of India. Placing a lining in the well shaft helps create stability, and linings of wood or [wickerwork](https:\/\/en.wikipedia.org\/wiki\/Wicker \"Wicker\") date back at least as far as the [Iron Age](https:\/\/en.wikipedia.org\/wiki\/Iron_Age \"Iron Age\").\n\nWells have traditionally been sunk by hand digging, as is still the case in rural areas of the developing world. These wells are inexpensive and low-tech as they use mostly manual labour, and the structure can be lined with [brick](https:\/\/en.wikipedia.org\/wiki\/Brick \"Brick\") or stone as the excavation proceeds. A more modern method called [caissoning](https:\/\/en.wikipedia.org\/wiki\/Caisson_\\(engineering\\) \"Caisson (engineering)\") uses pre-cast reinforced concrete well rings that are lowered into the hole. Driven wells can be created in unconsolidated material with a well hole structure, which consists of a hardened drive point and a screen of perforated pipe, after which a pump is installed to collect the water. Deeper wells can be excavated by hand drilling methods or machine drilling, using a [bit](https:\/\/en.wikipedia.org\/wiki\/Drill_bit \"Drill bit\") in a [borehole](https:\/\/en.wikipedia.org\/wiki\/Borehole \"Borehole\"). Drilled wells are usually cased with a factory-made pipe composed of steel or plastic. Drilled wells can access water at much greater depths than dug wells.\n\nTwo broad classes of well are shallow or unconfined wells completed within the uppermost saturated [aquifer](https:\/\/en.wikipedia.org\/wiki\/Aquifer \"Aquifer\") at that location, and deep or confined wells, sunk through an impermeable stratum into an aquifer beneath. A collector well can be constructed adjacent to a freshwater lake or stream with water percolating through the intervening material. The site of a well can be selected by a [hydrogeologist](https:\/\/en.wikipedia.org\/wiki\/Hydrogeology \"Hydrogeology\"), or groundwater surveyor. Water may be pumped or hand drawn. Impurities from the surface can easily reach shallow sources and contamination of the supply by pathogens or chemical contaminants needs to be avoided. Well water typically contains more minerals in solution than surface water and may require [treatment](https:\/\/en.wikipedia.org\/wiki\/Water_treatment \"Water treatment\") before being potable. [Soil salination](https:\/\/en.wikipedia.org\/wiki\/Soil_salinity \"Soil salinity\") can occur as the water table falls and the surrounding soil begins to dry out. Another environmental problem is the potential for [methane](https:\/\/en.wikipedia.org\/wiki\/Methane \"Methane\") to seep into the water.\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/7\/7b\/Tunis1960-150_hg.jpg\/250px-Tunis1960-150_hg.jpg)](https:\/\/en.wikipedia.org\/wiki\/File:Tunis1960-150_hg.jpg)\n\nCamel drawing water from a well, [Djerba](https:\/\/en.wikipedia.org\/wiki\/Djerba \"Djerba\") island, Tunisia, 1960\n\nVery early [Neolithic](https:\/\/en.wikipedia.org\/wiki\/Neolithic \"Neolithic\") wells are known from the [Eastern Mediterranean](https:\/\/en.wikipedia.org\/wiki\/Eastern_Mediterranean \"Eastern Mediterranean\").[\\[1\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-1) The oldest reliably dated well is from the [pre-pottery neolithic](https:\/\/en.wikipedia.org\/wiki\/Prehistoric_Cyprus#Aceramic_Neolithic \"Prehistoric Cyprus\") (PPN) site of Kissonerga-Mylouthkia on [Cyprus](https:\/\/en.wikipedia.org\/wiki\/Cyprus \"Cyprus\"). At around 8400 BC a shaft (well 116) of circular diameter was driven through limestone to reach an [aquifer](https:\/\/en.wikipedia.org\/wiki\/Aquifer \"Aquifer\") at a depth of 8 metres (26 ft). Well 2070 from Kissonerga-Mylouthkia, dating to the late PPN, reaches a depth of 13 metres (43 ft). Other slightly younger wells are known from this site and from neighbouring Parekklisha-Shillourokambos. A first stone lined[\\[2\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-2) well of 5.5 metres (18 ft) depth is documented from a drowned final PPN (c. 7000 BC) site at ['Atlit-Yam](https:\/\/en.wikipedia.org\/wiki\/Atlit_Yam \"Atlit Yam\") off the coast near modern [Haifa](https:\/\/en.wikipedia.org\/wiki\/Haifa \"Haifa\") in [Israel](https:\/\/en.wikipedia.org\/wiki\/Israel \"Israel\").\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/7\/74\/K%C3%BCckhoven_%28Erkelenz%29%2C_Brunnenbaureste_um_5300_v._Ch._.jpg\/120px-K%C3%BCckhoven_%28Erkelenz%29%2C_Brunnenbaureste_um_5300_v._Ch._.jpg)](https:\/\/en.wikipedia.org\/wiki\/File:K%C3%BCckhoven_\\(Erkelenz\\),_Brunnenbaureste_um_5300_v._Ch._.jpg)\n\nNeolithic [Linear Pottery culture](https:\/\/en.wikipedia.org\/wiki\/Linear_Pottery_culture \"Linear Pottery culture\") well, 5300 BC, [Erkelenz](https:\/\/en.wikipedia.org\/wiki\/Erkelenz \"Erkelenz\"), Germany\n\nWood-lined wells are known from the early Neolithic [Linear Pottery culture](https:\/\/en.wikipedia.org\/wiki\/Linear_Pottery_culture \"Linear Pottery culture\"), for example in Ostrov, Czech Republic, dated 5265 BC,[\\[3\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-3) Kückhoven (an outlying centre of [Erkelenz](https:\/\/en.wikipedia.org\/wiki\/Erkelenz \"Erkelenz\")), dated 5300 BC,[\\[4\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-4) and [Eythra](https:\/\/en.wikipedia.org\/wiki\/Eythra \"Eythra\") in Schletz (an outlying centre of [Asparn an der Zaya](https:\/\/en.wikipedia.org\/wiki\/Asparn_an_der_Zaya \"Asparn an der Zaya\")) in [Austria](https:\/\/en.wikipedia.org\/wiki\/Austria \"Austria\"), dated 5200 BC.[\\[5\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-5)\n\nThe Neolithic Chinese discovered and made extensive use of deep drilled groundwater for drinking.\\[*[citation needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Citation_needed \"Wikipedia:Citation needed\")*\\] The Chinese text *[The Book of Changes](https:\/\/en.wikipedia.org\/wiki\/I_Ching \"I Ching\")*, originally a divination text of the Western Zhou dynasty (1046 -771 BC), contains an entry describing how the ancient Chinese maintained their wells and protected their sources of water.[\\[6\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-Kuhn2004-6) A well excavated at the [Hemedu](https:\/\/en.wikipedia.org\/wiki\/Hemudu_culture \"Hemudu culture\") excavation site was believed to have been built during the neolithic era.[\\[7\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-Chang2012-7) The well was cased by four rows of logs with a square frame attached to them at the top of the well. 60 additional tile wells southwest of Beijing are also believed to have been built around 600 BC for drinking and irrigation.[\\[7\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-Chang2012-7)[\\[8\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-8)\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/7\/73\/Model_well%2C_burial_find%2C_China%2C_Han_dynasty%2C_206_BC_to_220_AD%2C_earthenware_-_%C3%96stasiatiska_museet%2C_Stockholm_-_DSC09578.JPG\/250px-Model_well%2C_burial_find%2C_China%2C_Han_dynasty%2C_206_BC_to_220_AD%2C_earthenware_-_%C3%96stasiatiska_museet%2C_Stockholm_-_DSC09578.JPG)](https:\/\/en.wikipedia.org\/wiki\/File:Model_well,_burial_find,_China,_Han_dynasty,_206_BC_to_220_AD,_earthenware_-_%C3%96stasiatiska_museet,_Stockholm_-_DSC09578.JPG)\n\nA Chinese ceramic model of a well with a water [pulley](https:\/\/en.wikipedia.org\/wiki\/Pulley \"Pulley\") system, excavated from a tomb of the [Han dynasty](https:\/\/en.wikipedia.org\/wiki\/Han_dynasty \"Han dynasty\") (202 BC – 220 AD) period\n\nIn [Egypt](https:\/\/en.wikipedia.org\/wiki\/Egypt \"Egypt\"), [shadoofs](https:\/\/en.wikipedia.org\/wiki\/Shadoof \"Shadoof\") and [sakias](https:\/\/en.wikipedia.org\/wiki\/Sakia \"Sakia\") are used.[\\[9\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-9)[\\[10\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-10) The sakia is much more efficient, as it can bring up water from a depth of 10 metres (versus the 3 metres of the shadoof). The sakia is the Egyptian version of the [noria](https:\/\/en.wikipedia.org\/wiki\/Noria \"Noria\"). Some of the world's oldest known wells, located in Cyprus, date to 7000–8,500 BC.[\\[11\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-11) Two wells from the Neolithic period, around 6500 BC, have been discovered in Israel. One is in Atlit, on the northern coast of Israel, and the other is in the Jezreel Valley.[\\[12\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-12)\n\nWells for other purposes came along much later, historically. The first recorded [salt well](https:\/\/en.wikipedia.org\/wiki\/Salt_well \"Salt well\") was dug in the Sichuan province of China around 2,250 years ago. This was the first time that ancient water well technology was applied successfully for the exploitation of salt, and marked the beginning of Sichuan's salt drilling industry.[\\[6\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-Kuhn2004-6) The earliest known [oil wells](https:\/\/en.wikipedia.org\/wiki\/Oil_well \"Oil well\") were also drilled in China, in 347 CE. These wells had depths of up to about 240 metres (790 ft) and were drilled using [bits](https:\/\/en.wikipedia.org\/wiki\/Drill_bit \"Drill bit\") attached to [bamboo](https:\/\/en.wikipedia.org\/wiki\/Bamboo \"Bamboo\") poles.[\\[13\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-ASTM-13) The oil was burned to evaporate [brine](https:\/\/en.wikipedia.org\/wiki\/Brine \"Brine\") and produce [salt](https:\/\/en.wikipedia.org\/wiki\/Sodium_chloride \"Sodium chloride\"). By the 10th century, extensive [bamboo](https:\/\/en.wikipedia.org\/wiki\/Bamboo \"Bamboo\") pipelines connected oil wells with salt springs. The ancient records of China and [Japan](https:\/\/en.wikipedia.org\/wiki\/Japan \"Japan\") are said to contain many allusions to the use of natural gas for lighting and heating. Petroleum was known as *Burning water* in Japan in the 7th century.[\\[14\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-EB1911-14)\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/7\/77\/Uwaynat_bin_Hussain_water_well_near_Simaisma.jpg\/250px-Uwaynat_bin_Hussain_water_well_near_Simaisma.jpg)](https:\/\/en.wikipedia.org\/wiki\/File:Uwaynat_bin_Hussain_water_well_near_Simaisma.jpg)\n\nWater well near [Simaisma](https:\/\/en.wikipedia.org\/wiki\/Simaisma \"Simaisma\"), eastern Qatar\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/b\/b8\/Leather_bucket_of_a_well.jpg\/250px-Leather_bucket_of_a_well.jpg)](https:\/\/en.wikipedia.org\/wiki\/File:Leather_bucket_of_a_well.jpg)\n\nLeather bucket used for the water well\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/a\/a6\/Well%2C_Historical_Village_%2C_Bhaini_Sahib%2C_Ludhyana_%2C_Punjab_%2C_India.JPG\/250px-Well%2C_Historical_Village_%2C_Bhaini_Sahib%2C_Ludhyana_%2C_Punjab_%2C_India.JPG)](https:\/\/en.wikipedia.org\/wiki\/File:Well,_Historical_Village_,_Bhaini_Sahib,_Ludhyana_,_Punjab_,_India.JPG)\n\nWell, Historical Village, Bhaini Sahib, [Ludhiana](https:\/\/en.wikipedia.org\/wiki\/Ludhiana \"Ludhiana\"), [Punjab](https:\/\/en.wikipedia.org\/wiki\/Punjab,_India \"Punjab, India\"), India\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/d\/d6\/Well.handdug.cased.mali.jpg\/250px-Well.handdug.cased.mali.jpg)](https:\/\/en.wikipedia.org\/wiki\/File:Well.handdug.cased.mali.jpg)\n\nView into a hand-dug well cased with concrete rings. [Ouelessebougou](https:\/\/en.wikipedia.org\/wiki\/Ouelessebougou \"Ouelessebougou\"), Mali.\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/c\/ca\/Well_In_Kerala.JPG\/250px-Well_In_Kerala.JPG)](https:\/\/en.wikipedia.org\/wiki\/File:Well_In_Kerala.JPG)\n\nA dug well in a village in [Kerala](https:\/\/en.wikipedia.org\/wiki\/Kerala \"Kerala\"), India\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/5\/57\/Open_Well_-_flower_bag_shaped_wall_and_podium_01.jpg\/250px-Open_Well_-_flower_bag_shaped_wall_and_podium_01.jpg)](https:\/\/en.wikipedia.org\/wiki\/File:Open_Well_-_flower_bag_shaped_wall_and_podium_01.jpg)\n\nWell with a flower bag-shaped wall and podium\n\nUntil recent centuries, all artificial wells were [pumpless](https:\/\/en.wikipedia.org\/wiki\/Pump \"Pump\") hand-dug wells of varying degrees of sophistication, and they remain a very important source of [potable water](https:\/\/en.wikipedia.org\/wiki\/Potable_water \"Potable water\") in some rural developing areas, where they are routinely dug and used today. Their indispensability has produced a number of literary references, literal and figurative, including the reference to the incident of [Jesus](https:\/\/en.wikipedia.org\/wiki\/Jesus \"Jesus\") meeting a woman at [Jacob](https:\/\/en.wikipedia.org\/wiki\/Jacob \"Jacob\")'s well ([John](https:\/\/en.wikipedia.org\/wiki\/Gospel_of_John \"Gospel of John\") 4:6) in the Bible and the \"[Ding Dong Bell](https:\/\/en.wikipedia.org\/wiki\/Ding_Dong_Bell \"Ding Dong Bell\")\" [nursery rhyme](https:\/\/en.wikipedia.org\/wiki\/Nursery_rhyme \"Nursery rhyme\") about a cat in a well.\n\nHand-dug wells are excavations with diameters large enough to accommodate one or more people with shovels digging down to below the [water table](https:\/\/en.wikipedia.org\/wiki\/Water_table \"Water table\"). The excavation is braced horizontally to avoid landslide or erosion endangering the people digging. They can be lined with stone or brick; extending this lining upwards above the ground surface to form a wall around the well serves to reduce both contamination and accidental falls into the well.\n\nA more modern method called [caissoning](https:\/\/en.wikipedia.org\/wiki\/Caisson_\\(engineering\\) \"Caisson (engineering)\") uses reinforced concrete or plain concrete pre-cast well rings that are lowered into the hole. A well-digging team digs under a cutting ring and the well column slowly sinks into the [aquifer](https:\/\/en.wikipedia.org\/wiki\/Aquifer \"Aquifer\"), whilst protecting the team from collapse of the well [bore](https:\/\/en.wikipedia.org\/wiki\/Borehole \"Borehole\").\n\nHand-dug wells are inexpensive and low tech (compared to drilling) and they use mostly manual labour to access groundwater in rural locations of developing countries. They may be built with a high degree of community participation, or by local entrepreneurs who specialize in hand-dug wells. They have been successfully excavated to 60 metres (200 ft). They have low operational and maintenance costs, in part because water can be extracted by hand, without a pump. The water often comes from an aquifer or groundwater, and can be easily deepened, which may be necessary if the ground water level drops, by telescoping the lining further down into the aquifer. The yield of existing hand dug wells may be improved by deepening or introducing vertical tunnels or perforated pipes.\n\nDrawbacks to hand-dug wells are numerous. It can be impractical to hand dig wells in areas where hard rock is present, and they can be time-consuming to dig and line even in favourable areas. Because they exploit shallow aquifers, the well may be susceptible to yield fluctuations and possible contamination from surface water, including sewage. Hand dug well construction generally requires the use of a well trained construction team, and the capital investment for equipment such as concrete ring moulds, heavy lifting equipment, well shaft formwork, motorized de-watering pumps, and fuel can be large for people in developing countries. Construction of hand dug wells can be dangerous due to collapse of the well bore, falling objects and asphyxiation, including from dewatering pump exhaust fumes.\n\nThe [Woodingdean Water Well](https:\/\/en.wikipedia.org\/wiki\/Woodingdean_Water_Well \"Woodingdean Water Well\"), hand-dug between 1858 and 1862, is the deepest hand-dug well at 392 metres (1,285 ft).[\\[15\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-15) The [Big Well](https:\/\/en.wikipedia.org\/wiki\/Big_Well \"Big Well\") in [Greensburg, Kansas](https:\/\/en.wikipedia.org\/wiki\/Greensburg,_Kansas \"Greensburg, Kansas\"), is billed as the world's largest hand-dug well, at 109 feet (33 m) deep and 32 feet (9.8 m) in diameter. However, the *Well of Joseph* in the [Cairo Citadel](https:\/\/en.wikipedia.org\/wiki\/Cairo_Citadel \"Cairo Citadel\") at 280 feet (85 m) deep and the [Pozzo di San Patrizio](https:\/\/en.wikipedia.org\/wiki\/Pozzo_di_San_Patrizio \"Pozzo di San Patrizio\") (St. Patrick's Well) built in 1527 in [Orvieto, Italy](https:\/\/en.wikipedia.org\/wiki\/Orvieto \"Orvieto\"), at 61 metres (200 ft) deep by 13 metres (43 ft) wide[\\[16\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-16) are both larger by volume.\n\nDriven wells may be very simply created in unconsolidated material with a *well hole structure*, which consists of a hardened drive point and a screen (perforated pipe). The point is simply hammered into the ground, usually with a tripod and *driver*, with pipe sections added as needed. A driver is a weighted pipe that slides over the pipe being driven and is repeatedly dropped on it. When [groundwater](https:\/\/en.wikipedia.org\/wiki\/Groundwater \"Groundwater\") is encountered, the well is washed of sediment and a pump installed.[\\[17\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-17)\n\nDrilled wells are constructed using various types of drilling machines, such as top-head rotary, table rotary, or cable tool, which all use drilling stems that rotate to cut into the formation, thus the term \"drilling.\"\n\nDrilled wells can be excavated by simple hand drilling methods (augering, sludging, jetting, driving, hand percussion) or machine drilling (auger, rotary, percussion, down the hole hammer). Deep rock rotary drilling method is most common. Rotary can be used in 90% of formation types (consolidated).\n\nDrilled wells can get water from a much deeper level than dug wells can − often down to several hundred metres.[\\[18\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-18)\n\nDrilled wells with electric pumps are used throughout the world, typically in rural or sparsely populated areas, though many urban areas are supplied partly by municipal wells. Most shallow well drilling machines are mounted on large trucks, trailers, or tracked vehicle carriages. Water wells typically range from 3 to 18 metres (10–60 ft) deep, but in some areas it can go deeper than 900 metres (3,000 ft).\\[*[citation needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Citation_needed \"Wikipedia:Citation needed\")*\\]\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/5\/59\/Well_spudder_8606.jpg\/250px-Well_spudder_8606.jpg)](https:\/\/en.wikipedia.org\/wiki\/File:Well_spudder_8606.jpg)\n\n[Cable tool](https:\/\/en.wikipedia.org\/wiki\/Drilling_rig#Cable_tool_drilling \"Drilling rig\") water well drilling rig in [Kimball, West Virginia](https:\/\/en.wikipedia.org\/wiki\/Kimball,_West_Virginia \"Kimball, West Virginia\")\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/e\/e2\/AquaBellaPickard-v.jpg\/250px-AquaBellaPickard-v.jpg)](https:\/\/en.wikipedia.org\/wiki\/File:AquaBellaPickard-v.jpg)\n\nIsraeli geologist [Leo Picard](https:\/\/en.wikipedia.org\/wiki\/Leo_Picard \"Leo Picard\") (white shirt) inspects a drilled water well outside the depopulated Palestinian village of [Bayt Naqquba](https:\/\/en.wikipedia.org\/wiki\/Bayt_Naqquba \"Bayt Naqquba\")\n\nRotary drilling machines use a segmented steel drilling string, typically made up of 3m (10ft), 6 m (20 ft) to 8m (26ft) sections of steel tubing that are threaded together, with a [bit](https:\/\/en.wikipedia.org\/wiki\/Drill_bit#Well_drilling_bits \"Drill bit\") or other drilling device at the bottom end. Some rotary drilling machines are designed to install (by driving or drilling) a steel casing into the well in conjunction with the drilling of the actual bore hole. Air and\/or water is used as a circulation fluid to displace cuttings and cool bits during the drilling. Another form of rotary-style drilling, termed *mud rotary*, makes use of a specially made mud, or drilling fluid, which is constantly being altered during the drill so that it can consistently create enough hydraulic pressure to hold the side walls of the bore hole open, regardless of the presence of a casing in the well. Typically, boreholes drilled into solid rock are not cased until after the drilling process is completed, regardless of the machinery used.\n\nThe oldest form of drilling machinery is the [cable tool](https:\/\/en.wikipedia.org\/wiki\/Drilling_rig#Cable_tool_drilling \"Drilling rig\"), still used today. Specifically designed to raise and lower a bit into the bore hole, the *spudding* of the drill causes the bit to be raised and dropped onto the bottom of the hole, and the design of the cable causes the bit to twist at approximately 1⁄4 revolution per drop, thereby creating a drilling action. Unlike rotary drilling, cable tool drilling requires the drilling action to be stopped so that the bore hole can be bailed or emptied of drilled cuttings. Cable tool drilling rigs are rare as they tend to be 10x slower to drill through materials compared to similar diameter rotary air or rotary mud equipped rigs.\n\nDrilled wells are usually cased with a factory-made pipe, typically [steel](https:\/\/en.wikipedia.org\/wiki\/Steel \"Steel\") (in air rotary or cable tool drilling) or [plastic](https:\/\/en.wikipedia.org\/wiki\/Plastic \"Plastic\")\/[PVC](https:\/\/en.wikipedia.org\/wiki\/PVC \"PVC\") (in mud rotary wells, also present in wells drilled into solid rock). The casing is constructed by welding, either chemically or thermally, segments of casing together. If the casing is installed during the drilling, most drills will drive the casing into the ground as the bore hole advances, while some newer machines will actually allow for the casing to be rotated and drilled into the formation in a similar manner as the bit advancing just below. PVC or plastic is typically solvent welded and then lowered into the drilled well, vertically stacked with their ends nested and either glued or splined together. The sections of casing are usually 6 metres (20 ft) or more in length, and 4 to 12 in (10 to 30 cm) in diameter, depending on the intended use of the well and local groundwater conditions.\n\nSurface contamination of wells in the United States is typically controlled by the use of a *surface seal*. A large hole is drilled to a predetermined depth or to a confining formation (clay or bedrock, for example), and then a smaller hole for the well is completed from that point forward. The well is typically cased from the surface down into the smaller hole with a casing that is the same diameter as that hole. The annular space between the large bore hole and the smaller casing is filled with [bentonite clay](https:\/\/en.wikipedia.org\/wiki\/Bentonite_clay \"Bentonite clay\"), concrete, or other sealant material. This creates an impermeable seal from the surface to the next confining layer that keeps contaminants from traveling down the outer sidewalls of the casing or borehole and into the [aquifer](https:\/\/en.wikipedia.org\/wiki\/Aquifer \"Aquifer\"). In addition, wells are typically capped with either an engineered well cap or seal that vents air through a screen into the well, but keeps insects, small animals, and unauthorized persons from accessing the well.\n\nAt the bottom of wells, based on formation, a screening device, filter pack, slotted casing, or open bore hole is left to allow the flow of water into the well. Constructed screens are typically used in unconsolidated formations (sands, gravels, etc.), allowing water and a percentage of the formation to pass through the screen. Allowing some material to pass through creates a large area filter out of the rest of the formation, as the amount of material present to pass into the well slowly decreases and is removed from the well. Rock wells are typically cased with a PVC liner\/casing and screen or slotted casing at the bottom, this is mostly present just to keep rocks from entering the pump assembly. Some wells use a *filter pack* method, where an undersized screen or slotted casing is placed inside the well and a filter medium is packed around the screen, between the screen and the borehole or casing. This allows the water to be filtered of unwanted materials before entering the well and pumping zone.\n\n- [![An automated water well system powered by a jet-pump](https:\/\/upload.wikimedia.org\/wikipedia\/en\/thumb\/8\/8e\/Jet-pump_System.svg\/120px-Jet-pump_System.svg.png)](https:\/\/en.wikipedia.org\/wiki\/File:Jet-pump_System.svg \"An automated water well system powered by a jet-pump\")\n  An automated water well system powered by a jet-pump\n- [![An automated water well system powered by a submersible pump](https:\/\/upload.wikimedia.org\/wikipedia\/en\/thumb\/2\/28\/Submersible-pump_System.svg\/120px-Submersible-pump_System.svg.png)](https:\/\/en.wikipedia.org\/wiki\/File:Submersible-pump_System.svg \"An automated water well system powered by a submersible pump\")\n  An automated water well system powered by a submersible pump\n- [![A water well system with a cistern](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/f\/f1\/Water_System_With_Cistern.svg\/120px-Water_System_With_Cistern.svg.png)](https:\/\/en.wikipedia.org\/wiki\/File:Water_System_With_Cistern.svg \"A water well system with a cistern\")\n  A water well system with a cistern\n- [![A water well system with a pressurized cistern](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/8\/8e\/Water_System_With_Pressurized_Cistern.svg\/120px-Water_System_With_Pressurized_Cistern.svg.png)](https:\/\/en.wikipedia.org\/wiki\/File:Water_System_With_Pressurized_Cistern.svg \"A water well system with a pressurized cistern\")\n  A water well system with a pressurized cistern\n- [![A section of a stainless steel screen well](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/5\/5d\/Screen_tube.JPG\/120px-Screen_tube.JPG)](https:\/\/en.wikipedia.org\/wiki\/File:Screen_tube.JPG \"A section of a stainless steel screen well\")\n  A section of a stainless steel screen well\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/c\/c2\/Water_well_types_wiki.svg\/500px-Water_well_types_wiki.svg.png)](https:\/\/en.wikipedia.org\/wiki\/File:Water_well_types_wiki.svg)\n\nWater well types\n\nThere are two broad classes of drilled-well types, based on the type of [aquifer](https:\/\/en.wikipedia.org\/wiki\/Aquifer \"Aquifer\") the well is in:\n\n- *Shallow* or *unconfined wells* are completed in the uppermost saturated aquifer at that location (the upper unconfined aquifer).\\[*[citation needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Citation_needed \"Wikipedia:Citation needed\")*\\]\n- *Deep* or *confined wells* are sunk through an impermeable stratum into an aquifer that is sandwiched between two impermeable strata (aquitards or aquicludes). The majority of deep aquifers are classified as artesian because the hydraulic head in a confined well is higher than the level of the top of the aquifer. If the hydraulic head in a confined well is higher than the land surface it is a \"flowing\" [artesian well](https:\/\/en.wikipedia.org\/wiki\/Artesian_well \"Artesian well\") (named after [Artois](https:\/\/en.wikipedia.org\/wiki\/Artois \"Artois\") in [France](https:\/\/en.wikipedia.org\/wiki\/France \"France\")).[\\[19\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-19)\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/7\/75\/Old-fashioned_well_in_Finland.JPG\/250px-Old-fashioned_well_in_Finland.JPG)](https:\/\/en.wikipedia.org\/wiki\/File:Old-fashioned_well_in_Finland.JPG)\n\nAn old-fashioned water well in the countryside of [Utajärvi](https:\/\/en.wikipedia.org\/wiki\/Utaj%C3%A4rvi \"Utajärvi\"), [Finland](https:\/\/en.wikipedia.org\/wiki\/Finland \"Finland\")\n\nA special type of water well may be constructed adjacent to freshwater lakes or streams. Commonly called a collector well but sometimes referred to by the trade name Ranney well or [Ranney collector](https:\/\/en.wikipedia.org\/wiki\/Ranney_collector \"Ranney collector\"), this type of well involves sinking a caisson vertically below the top of the aquifer and then advancing lateral collectors out of the caisson and beneath the surface water body. Pumping from within the caisson induces infiltration of water from the surface water body into the aquifer, where it is collected by the collector well laterals and conveyed into the caisson where it can be pumped to the ground surface.\\[*[citation needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Citation_needed \"Wikipedia:Citation needed\")*\\]\n\nTwo additional broad classes of well types may be distinguished, based on the use of the well:\n\n- *production* or *pumping wells*, are large diameter (greater than 15 cm in diameter) cased (metal, plastic, or concrete) water wells, constructed for extracting water from the aquifer by a [pump](https:\/\/en.wikipedia.org\/wiki\/Pump \"Pump\") (if the well is not [artesian](https:\/\/en.wikipedia.org\/wiki\/Artesian_aquifer \"Artesian aquifer\")).\\[*[citation needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Citation_needed \"Wikipedia:Citation needed\")*\\]\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/5\/5c\/Well_schematic.pdf\/page1-250px-Well_schematic.pdf.jpg)](https:\/\/en.wikipedia.org\/wiki\/File:Well_schematic.pdf)\n\nSchematic diagram of a groundwater monitoring well\n\n- *monitoring wells* or *[piezometers](https:\/\/en.wikipedia.org\/wiki\/Piezometer \"Piezometer\")*, are often smaller diameter wells used to monitor the hydraulic head or sample the groundwater for chemical constituents. Piezometers are monitoring wells completed over a very short section of aquifer. Monitoring wells can also be completed at multiple levels, allowing discrete samples or measurements to be made at different vertical elevations at the same map location.[\\[20\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-20)\n\nA water well constructed for pumping groundwater can be used passively as a monitoring well and a small diameter well can be pumped, but this distinction by use is common.\\[*[citation needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Citation_needed \"Wikipedia:Citation needed\")*\\]\n\nBefore excavation, information about the geology, water table depth, seasonal fluctuations, recharge area and rate should be found if possible. This work can be done by a [hydrogeologist](https:\/\/en.wikipedia.org\/wiki\/Hydrogeologist \"Hydrogeologist\"), or a groundwater surveyor using a variety of tools including electro-seismic surveying,[\\[21\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-21) any available information from nearby wells, geologic maps, and sometimes [geophysical imaging](https:\/\/en.wikipedia.org\/wiki\/Geophysical_imaging \"Geophysical imaging\"). These professionals provide advice that is almost as accurate a driller who has experience and knowledge of nearby wells\/bores and the most suitable drilling technique based on the expected target depth.\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/9\/9d\/Groundwater_Contamination_Latin_America_Sm.png\/250px-Groundwater_Contamination_Latin_America_Sm.png)](https:\/\/en.wikipedia.org\/wiki\/File:Groundwater_Contamination_Latin_America_Sm.png)\n\n[Waterborne diseases](https:\/\/en.wikipedia.org\/wiki\/Waterborne_diseases \"Waterborne diseases\") can be spread via a well which is contaminated with fecal pathogens from [pit latrines](https:\/\/en.wikipedia.org\/wiki\/Pit_latrine \"Pit latrine\").\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/b\/b4\/Cleaning_a_well_in_Yaounde.jpg\/250px-Cleaning_a_well_in_Yaounde.jpg)](https:\/\/en.wikipedia.org\/wiki\/File:Cleaning_a_well_in_Yaounde.jpg)\n\nMan cleaning a well in [Yaoundé](https:\/\/en.wikipedia.org\/wiki\/Yaound%C3%A9 \"Yaoundé\"), [Cameroon](https:\/\/en.wikipedia.org\/wiki\/Cameroon \"Cameroon\")\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/b\/b4\/Hand_water_pump_in_India_%283382861084%29.jpg\/250px-Hand_water_pump_in_India_%283382861084%29.jpg)](https:\/\/en.wikipedia.org\/wiki\/File:Hand_water_pump_in_India_\\(3382861084\\).jpg)\n\nHand pump to pump water from a well in a village near Chennai in India, where the well water might be polluted by nearby [pit latrines](https:\/\/en.wikipedia.org\/wiki\/Pit_latrine \"Pit latrine\").\n\nShallow pumping wells can often supply [drinking water](https:\/\/en.wikipedia.org\/wiki\/Drinking_water \"Drinking water\") at a very low cost. However, impurities from the surface easily reach shallow sources, which leads to a greater risk of contamination for these wells compared to deeper wells. Contaminated wells can lead to the spread of various [waterborne diseases](https:\/\/en.wikipedia.org\/wiki\/Waterborne_diseases \"Waterborne diseases\"). Dug and driven wells are relatively easy to contaminate; for instance, most dug wells are unreliable in the majority of the United States.[\\[22\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-CEH-CID-22) Some research has found that, in cold regions, changes in river flow and flooding caused by extreme rainfall or snowmelt can degrade well water quality.[\\[23\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-23)\n\nMost of the [bacteria](https:\/\/en.wikipedia.org\/wiki\/Bacteria \"Bacteria\"), [viruses](https:\/\/en.wikipedia.org\/wiki\/Viruses \"Viruses\"), [parasites](https:\/\/en.wikipedia.org\/wiki\/Parasite \"Parasite\"), and [fungi](https:\/\/en.wikipedia.org\/wiki\/Fungi \"Fungi\") that contaminate well water comes from [fecal material](https:\/\/en.wikipedia.org\/wiki\/Feces \"Feces\") from humans and other animals. Common bacterial contaminants include *[E. coli](https:\/\/en.wikipedia.org\/wiki\/E._coli \"E. coli\")*, *[Salmonella](https:\/\/en.wikipedia.org\/wiki\/Salmonella \"Salmonella\")*, *[Shigella](https:\/\/en.wikipedia.org\/wiki\/Shigella \"Shigella\")*, and *[Campylobacter jejuni](https:\/\/en.wikipedia.org\/wiki\/Campylobacter_jejuni \"Campylobacter jejuni\")*. Common viral contaminants include *[norovirus](https:\/\/en.wikipedia.org\/wiki\/Norovirus \"Norovirus\")*, *[sapovirus](https:\/\/en.wikipedia.org\/wiki\/Sapovirus \"Sapovirus\")*, *[rotavirus](https:\/\/en.wikipedia.org\/wiki\/Rotavirus \"Rotavirus\")*, [enteroviruses](https:\/\/en.wikipedia.org\/wiki\/Enterovirus \"Enterovirus\"), and [hepatitis A](https:\/\/en.wikipedia.org\/wiki\/Hepatitis_A \"Hepatitis A\") and [E](https:\/\/en.wikipedia.org\/wiki\/Hepatitis_E \"Hepatitis E\"). Parasites include *[Giardia lamblia](https:\/\/en.wikipedia.org\/wiki\/Giardia_lamblia \"Giardia lamblia\")*, *[Cryptosporidium](https:\/\/en.wikipedia.org\/wiki\/Cryptosporidium \"Cryptosporidium\")*, *[Cyclospora cayetanensis](https:\/\/en.wikipedia.org\/wiki\/Cyclospora_cayetanensis \"Cyclospora cayetanensis\")*, and [microsporidia](https:\/\/en.wikipedia.org\/wiki\/Microsporidia \"Microsporidia\").[\\[22\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-CEH-CID-22)\n\n### Chemical contamination\n\\[[edit](https:\/\/en.wikipedia.org\/w\/index.php?title=Well&action=edit&section=10 \"Edit section: Chemical contamination\")\\]\n\nChemical contamination is a common problem with groundwater.[\\[24\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-24) [Nitrates](https:\/\/en.wikipedia.org\/wiki\/Nitrate \"Nitrate\") from [sewage](https:\/\/en.wikipedia.org\/wiki\/Sewage \"Sewage\"), [sewage sludge](https:\/\/en.wikipedia.org\/wiki\/Sewage_sludge \"Sewage sludge\") or [fertilizer](https:\/\/en.wikipedia.org\/wiki\/Fertilizer \"Fertilizer\") are a particular problem for babies and young children. Pollutant chemicals include [pesticides](https:\/\/en.wikipedia.org\/wiki\/Pesticide \"Pesticide\") and [volatile organic compounds](https:\/\/en.wikipedia.org\/wiki\/Volatile_organic_compound \"Volatile organic compound\") from [gasoline](https:\/\/en.wikipedia.org\/wiki\/Gasoline \"Gasoline\"), [dry-cleaning](https:\/\/en.wikipedia.org\/wiki\/Dry-cleaning \"Dry-cleaning\"), the fuel additive [methyl tert-butyl ether](https:\/\/en.wikipedia.org\/wiki\/Methyl_tert-butyl_ether \"Methyl tert-butyl ether\") (MTBE), and [perchlorate](https:\/\/en.wikipedia.org\/wiki\/Perchlorate \"Perchlorate\") from rocket fuel, airbag inflators, and other artificial and natural sources.\\[*[citation needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Citation_needed \"Wikipedia:Citation needed\")*\\]\n\nSeveral minerals are also contaminants, including [lead](https:\/\/en.wikipedia.org\/wiki\/Lead \"Lead\") leached from brass fittings or old lead pipes, [chromium VI](https:\/\/en.wikipedia.org\/wiki\/Chromium_VI \"Chromium VI\") from electroplating and other sources, naturally occurring [arsenic](https:\/\/en.wikipedia.org\/wiki\/Arsenic \"Arsenic\"), [radon](https:\/\/en.wikipedia.org\/wiki\/Radon \"Radon\"), and [uranium](https:\/\/en.wikipedia.org\/wiki\/Uranium \"Uranium\")—all of which can cause cancer—and naturally occurring [fluoride](https:\/\/en.wikipedia.org\/wiki\/Fluoride \"Fluoride\"), which is desirable in low quantities to prevent [tooth decay](https:\/\/en.wikipedia.org\/wiki\/Tooth_decay \"Tooth decay\"), but can cause [dental fluorosis](https:\/\/en.wikipedia.org\/wiki\/Dental_fluorosis \"Dental fluorosis\") in higher concentrations.[\\[22\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-CEH-CID-22)\n\nSome chemicals are commonly present in water wells at levels that are not toxic, but can cause other problems. [Calcium](https:\/\/en.wikipedia.org\/wiki\/Calcium \"Calcium\") and [magnesium](https:\/\/en.wikipedia.org\/wiki\/Magnesium \"Magnesium\") cause what is known as [hard water](https:\/\/en.wikipedia.org\/wiki\/Hard_water \"Hard water\"), which can precipitate and clog pipes or burn out water heaters. [Iron](https:\/\/en.wikipedia.org\/wiki\/Iron \"Iron\") and [manganese](https:\/\/en.wikipedia.org\/wiki\/Manganese \"Manganese\") can appear as dark flecks that stain clothing and plumbing, and can promote the growth of [iron and manganese bacteria](https:\/\/en.wikipedia.org\/wiki\/Iron_bacteria \"Iron bacteria\") that can form slimy black colonies that clog pipes.[\\[22\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-CEH-CID-22)\n\nThe quality of the well water can be significantly increased by lining the well, sealing the well head, fitting a self-priming hand pump, constructing an apron, ensuring the area is kept clean and free from stagnant water and animals, moving sources of contamination ([pit latrines](https:\/\/en.wikipedia.org\/wiki\/Pit_latrine \"Pit latrine\"), garbage pits, [on-site sewer systems](https:\/\/en.wikipedia.org\/wiki\/Onsite_sewage_facility \"Onsite sewage facility\")) and carrying out hygiene education. The well should be cleaned with 1% chlorine solution after construction and periodically every 6 months.\\[*[citation needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Citation_needed \"Wikipedia:Citation needed\")*\\]\n\nWell holes should be covered to prevent loose debris, animals, animal excrement, and wind-blown foreign matter from falling into the hole and decomposing. The cover should be able to be in place at all times, including when drawing water from the well. A suspended roof over an open hole helps to some degree, but ideally the cover should be tight fitting and fully enclosing, with only a screened air vent.\\[*[citation needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Citation_needed \"Wikipedia:Citation needed\")*\\]\n\nMinimum distances and soil percolation requirements between sewage disposal sites and water wells need to be observed. Rules regarding the design and installation of private and municipal septic systems take all these factors into account so that nearby drinking water sources are protected.\n\nEducation of the general population in society also plays an important role in protecting drinking water.\\[*[citation needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Citation_needed \"Wikipedia:Citation needed\")*\\]\n\nCleanup of [contaminated groundwater](https:\/\/en.wikipedia.org\/wiki\/Contaminated_groundwater \"Contaminated groundwater\") tends to be very costly. Effective [remediation of groundwater](https:\/\/en.wikipedia.org\/wiki\/Groundwater_remediation \"Groundwater remediation\") is generally very difficult. Contamination of groundwater from surface and subsurface sources can usually be dramatically reduced by correctly centering the casing during construction and filling the casing [annulus](https:\/\/en.wikipedia.org\/wiki\/Annulus_\\(well\\) \"Annulus (well)\") with an appropriate sealing material. The sealing material (grout) should be placed from immediately above the production zone back to surface, because, in the absence of a correctly constructed casing seal, contaminated fluid can travel into the well through the casing annulus. Centering devices are important (usually one per length of casing or at maximum intervals of 9 m) to ensure that the grouted annular space is of even thickness.\\[*[citation needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Citation_needed \"Wikipedia:Citation needed\")*\\]\n\nUpon the construction of a new test well, it is considered best practice to invest in a complete battery of chemical and biological tests on the well water in question. Point-of-use treatment is available for individual properties and treatment plants are often constructed for municipal water supplies that suffer from contamination. Most of these treatment methods involve the [filtration](https:\/\/en.wikipedia.org\/wiki\/Filtration \"Filtration\") of the contaminants of concern, and additional protection may be garnered by installing well-casing screens only at depths where contamination is not present.\\[*[citation needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Citation_needed \"Wikipedia:Citation needed\")*\\]\n\nWellwater for personal use is often filtered with [reverse osmosis](https:\/\/en.wikipedia.org\/wiki\/Reverse_osmosis \"Reverse osmosis\") water processors; this process can remove very small particles. A simple, effective way of killing microorganisms is to bring the water to a full boil for one to three minutes, depending on location. A household well contaminated by microorganisms can initially be treated by shock chlorination using bleach, generating concentrations hundreds of times greater than found in community water systems; however, this will not fix any structural problems that led to the contamination and generally requires some expertise and testing for effective application.[\\[22\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-CEH-CID-22)\n\nAfter the filtration process, it is common to implement an [ultraviolet](https:\/\/en.wikipedia.org\/wiki\/Ultraviolet_germicidal_irradiation \"Ultraviolet germicidal irradiation\") (UV) system to kill pathogens in the water. UV light affects the DNA of the pathogen by UV-C photons breaking through the cell wall. UV disinfection has been gaining popularity in the past decades as it is a chemical-free method of water treatment.[\\[25\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-25)\n\n## Environmental problems\n\\[[edit](https:\/\/en.wikipedia.org\/w\/index.php?title=Well&action=edit&section=13 \"Edit section: Environmental problems\")\\]\n\nA risk with the placement of water wells is [soil salination](https:\/\/en.wikipedia.org\/wiki\/Soil_salinity \"Soil salinity\") which occurs when the water table of the soil begins to drop and salt begins to accumulate as the soil begins to dry out.[\\[26\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-26) Another environmental problem that is very prevalent in water well drilling is the potential for methane to seep through.\n\nThe potential for soil salination is a large risk when choosing the placement of water wells. Soil salination is caused when the water table of the soil drops over time and salt begins to accumulate. In turn, the increased amount of salt begins to dry the soil out. The increased level of salt in the soil can result in the degradation of soil and can be very harmful to vegetation.\\[*[citation needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Citation_needed \"Wikipedia:Citation needed\")*\\]\n\n[Methane](https:\/\/en.wikipedia.org\/wiki\/Methane \"Methane\"), an asphyxiant, is a chemical compound that is the main component of natural gas. When methane is introduced into a confined space, it displaces oxygen, reducing oxygen concentration to a level low enough to pose a threat to humans and other aerobic organisms but still high enough for a risk of [spontaneous](https:\/\/en.wikipedia.org\/wiki\/Spontaneous_combustion \"Spontaneous combustion\") or externally caused explosion. This potential for explosion is what poses such a danger in regards to the drilling and placement of water wells.\\[*[citation needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Citation_needed \"Wikipedia:Citation needed\")*\\]\n\nLow levels of methane in drinking water are not considered toxic. When methane seeps into a water supply, it is commonly referred to as \"methane migration\". This can be caused by old natural gas wells near water well systems becoming abandoned and no longer monitored.\\[*[citation needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Citation_needed \"Wikipedia:Citation needed\")*\\]\n\nLately,\\[*[when?](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Manual_of_Style\/Dates_and_numbers#Chronological_items \"Wikipedia:Manual of Style\/Dates and numbers\")*\\] however, the described wells\/pumps are no longer very efficient and can be replaced by either [handpumps](https:\/\/en.wikipedia.org\/wiki\/Handpump \"Handpump\") or [treadle pumps](https:\/\/en.wikipedia.org\/wiki\/Treadle_pump \"Treadle pump\"). Another alternative is the use of self-dug wells, electrical deep-well pumps (for higher depths). [Appropriate technology](https:\/\/en.wikipedia.org\/wiki\/Appropriate_technology \"Appropriate technology\") organizations as [Practical Action](https:\/\/en.wikipedia.org\/wiki\/Practical_Action \"Practical Action\") are now\\[*[when?](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Manual_of_Style\/Dates_and_numbers#Chronological_items \"Wikipedia:Manual of Style\/Dates and numbers\")*\\] supplying information on how to build\/set-up ([DIY](https:\/\/en.wikipedia.org\/wiki\/Do_it_yourself \"Do it yourself\")) handpumps and [treadle pumps](https:\/\/en.wikipedia.org\/wiki\/Treadle_pump \"Treadle pump\") in practice.[\\[27\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-27)[\\[28\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-28)\n\n### PFAS\/PFOS Fire fighting foam\n\\[[edit](https:\/\/en.wikipedia.org\/w\/index.php?title=Well&action=edit&section=16 \"Edit section: PFAS\/PFOS Fire fighting foam\")\\]\n\n**Per- and polyfluoroalkyl substances** (**[PFAS](https:\/\/en.wikipedia.org\/wiki\/Per-_and_polyfluoroalkyl_substances \"Per- and polyfluoroalkyl substances\")** or **PFASs**) are a group of synthetic [organofluorine](https:\/\/en.wikipedia.org\/wiki\/Organofluorine_chemistry \"Organofluorine chemistry\") [chemical compounds](https:\/\/en.wikipedia.org\/wiki\/Chemical_compound \"Chemical compound\") that have multiple [fluorine](https:\/\/en.wikipedia.org\/wiki\/Fluorine \"Fluorine\") atoms attached to an [alkyl](https:\/\/en.wikipedia.org\/wiki\/Alkyl \"Alkyl\") chain. PFAS are a group of \"forever chemicals\" that spread very quickly and very far in ground water polluting it permanently. Water wells near certain airports where any foam fire fighting or training activities occurred up to 2010 are likely to be contaminated by PFAS.\n\nA study concluded that of ~39 million groundwater wells 9-20% are at [high risk of running dry](https:\/\/en.wikipedia.org\/wiki\/Water_security \"Water security\") if local groundwater levels decline by less than five meters, or – as with many areas and possibly more than half of major [aquifers](https:\/\/en.wikipedia.org\/wiki\/Aquifer \"Aquifer\")[\\[29\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-29) – continue to decline.[\\[30\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-30)[\\[31\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-31)\\[*[further explanation needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Please_clarify \"Wikipedia:Please clarify\")*\\]\n\n## Society and culture\n\\[[edit](https:\/\/en.wikipedia.org\/w\/index.php?title=Well&action=edit&section=18 \"Edit section: Society and culture\")\\]\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/6\/6a\/22-alimenti%2C_acqua_dolce%2CTaccuino_Sanitatis%2C_Casanatense_418.jpg\/250px-22-alimenti%2C_acqua_dolce%2CTaccuino_Sanitatis%2C_Casanatense_418.jpg)](https:\/\/en.wikipedia.org\/wiki\/File:22-alimenti,_acqua_dolce,Taccuino_Sanitatis,_Casanatense_418.jpg)\n\nWater use, [Tacuinum Sanitatis](https:\/\/en.wikipedia.org\/wiki\/Tacuinum_Sanitatis \"Tacuinum Sanitatis\"), [Biblioteca Casanatense](https:\/\/en.wikipedia.org\/wiki\/Biblioteca_Casanatense \"Biblioteca Casanatense\") (14th century)\n\n[Springs](https:\/\/en.wikipedia.org\/wiki\/Spring_\\(hydrology\\) \"Spring (hydrology)\") and wells have had [cultural significance](https:\/\/en.wikipedia.org\/wiki\/Cultural_significance \"Cultural significance\") since [prehistoric](https:\/\/en.wikipedia.org\/wiki\/Prehistoric \"Prehistoric\") times, leading to the foundation of towns such as [Wells](https:\/\/en.wikipedia.org\/wiki\/Wells,_Somerset \"Wells, Somerset\") and [Bath](https:\/\/en.wikipedia.org\/wiki\/Bath,_Somerset \"Bath, Somerset\") in [Somerset](https:\/\/en.wikipedia.org\/wiki\/Somerset \"Somerset\"). Interest in health benefits led to the growth of [spa towns](https:\/\/en.wikipedia.org\/wiki\/Spa_town \"Spa town\") including many with *wells* in their name, examples being [Llandrindod Wells](https:\/\/en.wikipedia.org\/wiki\/Llandrindod_Wells \"Llandrindod Wells\") and [Royal Tunbridge Wells](https:\/\/en.wikipedia.org\/wiki\/Royal_Tunbridge_Wells \"Royal Tunbridge Wells\").[\\[32\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-Burr-32)\n\n[Eratosthenes](https:\/\/en.wikipedia.org\/wiki\/Eratosthenes \"Eratosthenes\") is sometimes claimed to have used a well in his calculation of the [Earth's circumference](https:\/\/en.wikipedia.org\/wiki\/Earth%27s_circumference \"Earth's circumference\"); however, this is just a simplification used in a shorter explanation of [Cleomedes](https:\/\/en.wikipedia.org\/wiki\/Cleomedes \"Cleomedes\"), since Eratosthenes had used a more elaborate and precise method.[\\[33\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-russo273277-33)\n\nMany incidents in the [Bible](https:\/\/en.wikipedia.org\/wiki\/Bible \"Bible\") take place around wells, such as the finding of a wife for [Isaac](https:\/\/en.wikipedia.org\/wiki\/Isaac \"Isaac\") in [Genesis](https:\/\/en.wikipedia.org\/wiki\/Book_of_Genesis \"Book of Genesis\") and [Jesus](https:\/\/en.wikipedia.org\/wiki\/Jesus \"Jesus\")'s talk with the Samaritan woman in the [Gospels](https:\/\/en.wikipedia.org\/wiki\/Gospels \"Gospels\").[\\[34\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-34)\n\n## A simple model for water well recovery\n\\[[edit](https:\/\/en.wikipedia.org\/w\/index.php?title=Well&action=edit&section=19 \"Edit section: A simple model for water well recovery\")\\]\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/5\/57\/Well_Recovery_diagram.jpg\/250px-Well_Recovery_diagram.jpg)](https:\/\/en.wikipedia.org\/wiki\/File:Well_Recovery_diagram.jpg)\n\nDiagram of a water well partially filled to level *z* with the top of the aquifer at *zT*\n\nFor a well with impermeable walls, the water in the well is resupplied from the bottom of the well. The rate at which water flows into the well will depend on the pressure difference between the ground water at the well bottom and the well water at the well bottom. The pressure of a column of water of height *z* will be equal to the weight of the water in the column divided by the cross-sectional area of the column, so the pressure of the ground water a distance *zT* below the top of the water table will be:\n\n![{\\\\displaystyle P\\_{g}=\\\\rho \\\\,g\\\\,z\\_{T}}](https:\/\/wikimedia.org\/api\/rest_v1\/media\/math\/render\/svg\/638cbf760d9b102d42a0fe61424cfbb84eb644ed)\n\nwhere *ρ* is the mass density of the water and *g* is the acceleration due to gravity. When the water in the well is below the water table level, the pressure at the bottom of the well due to the water in the well will be less than *Pg* and water will be forced into the well. Referring to the diagram, if *z* is the distance from the bottom of the well to the well water level and *zT* is the distance from the bottom of the well to the top of the water table, the pressure difference will be:\n\n![{\\\\displaystyle \\\\Delta P=\\\\rho \\\\,g\\\\,(z\\_{T}-z)}](https:\/\/wikimedia.org\/api\/rest_v1\/media\/math\/render\/svg\/311a95e84de02b5c6e319eedd8feb50ea181063e)\n\nApplying [Darcy's law](https:\/\/en.wikipedia.org\/wiki\/Darcy%27s_law \"Darcy's law\"), the volume rate (*F*) at which water is forced into the well will be proportional to this pressure difference:\n\n![{\\\\displaystyle \\\\Delta P=R\\\\,F}](https:\/\/wikimedia.org\/api\/rest_v1\/media\/math\/render\/svg\/5786632d6b2bb052677675191ea1e572c14aaa15)\n\nwhere *R* is the resistance to the flow, which depends on the well cross section, the pressure gradient at the bottom of the well, and the characteristics of the substrate at the well bottom. (e.g., porosity). The volume flow rate into the well can be written as a function of the rate of change of the well water level:\n\n![{\\\\displaystyle F=A{\\\\frac {dz}{dt}}}](https:\/\/wikimedia.org\/api\/rest_v1\/media\/math\/render\/svg\/2a739564c0695861c243527e15701b5380b474c5)\n\nCombining the above three equations yields a simple differential equation in *z*:\n\n![{\\\\displaystyle RA{\\\\frac {dz}{dt}}=\\\\rho g(z\\_{T}-z)}](https:\/\/wikimedia.org\/api\/rest_v1\/media\/math\/render\/svg\/17afdd8ee77364f91732322618429ae09d2a4fe0)\n\nwhich may be solved:\n\n![{\\\\displaystyle z=z\\_{T}-(z\\_{T}-z\\_{0})e^{-t\/\\\\tau }}](https:\/\/wikimedia.org\/api\/rest_v1\/media\/math\/render\/svg\/16df3ea8a895dd6cd73a39111821a175b1c5d98d)\n\nwhere *z0* is the well water level at time *t=0* and *τ* is the well time constant:\n\n![{\\\\displaystyle \\\\tau ={\\\\frac {RA}{\\\\rho g}}}](https:\/\/wikimedia.org\/api\/rest_v1\/media\/math\/render\/svg\/01cd2f59d9c030817d81d1c8ab981b070faa8d3b)\n\nNote that if *dz\/dt* for a depleted well can be measured, it will be equal to ![{\\\\displaystyle z\\_{T}\/\\\\tau }](https:\/\/wikimedia.org\/api\/rest_v1\/media\/math\/render\/svg\/b72aa8e3c928e0d99f543788380c18fe540ac987) and the time constant τ can be calculated. According to the above model, it will take an infinite amount of time for a well to fully recover, but if we consider a well that is 99% recovered to be \"practically\" recovered, the time for a well to practically recover from a level at *z* will be:\n\n![{\\\\displaystyle T\\_{r}=\\\\tau \\\\ln \\\\left({\\\\frac {1-z\/z\\_{T}}{1-0.99}}\\\\right)}](https:\/\/wikimedia.org\/api\/rest_v1\/media\/math\/render\/svg\/3db7a070422bcbfe86695fa9ed06fb1261b8d06a)\n\nFor a well that is fully depleted (*z=0*) it would take a time of about *4\\.6 τ* to practically recover.\n\nThe above model does not take into account the depletion of the aquifer due to the pumping which lowered the well water level (See [aquifer test](https:\/\/en.wikipedia.org\/wiki\/Aquifer_test \"Aquifer test\") and [groundwater flow equation](https:\/\/en.wikipedia.org\/wiki\/Groundwater_flow_equation \"Groundwater flow equation\")). Also, practical wells may have impermeable walls only up to, but not including the bedrock, which will give a larger surface area for water to enter the well.[\\[35\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-Humboldt-35)[\\[36\\]](https:\/\/en.wikipedia.org\/wiki\/Well#cite_note-Inspectapedia-36)\n\n- Types of ancient wells\n  - [Brick-lined well](https:\/\/en.wikipedia.org\/wiki\/Brick-lined_well \"Brick-lined well\")\n  - [Castle well](https:\/\/en.wikipedia.org\/wiki\/Castle_well \"Castle well\"), for use in the castle\n  - [Cistern](https:\/\/en.wikipedia.org\/wiki\/Cistern \"Cistern\"), ancient Greek\n  - [Stepwell](https:\/\/en.wikipedia.org\/wiki\/Stepwell \"Stepwell\"), ancient India\n\n- Modern construction techniques\n  - [Baptist well drilling](https:\/\/en.wikipedia.org\/wiki\/Baptist_well_drilling \"Baptist well drilling\"), simple technique\n  - [Rodriguez well](https:\/\/en.wikipedia.org\/wiki\/Rodriguez_well \"Rodriguez well\"), for harvesting drinking water in polar regions\n  - [Spring supply](https:\/\/en.wikipedia.org\/wiki\/Spring_supply \"Spring supply\"), piped water supply from the well\n\n- Uses\n  - [Holy well](https:\/\/en.wikipedia.org\/wiki\/Holy_well \"Holy well\"), sacred wells in various religions\n    - [Abraham's well](https:\/\/en.wikipedia.org\/wiki\/Abraham%27s_well \"Abraham's well\"), sacred well in Israel\n    - [Ghat](https:\/\/en.wikipedia.org\/wiki\/Ghat \"Ghat\"), sacred in Hinduism and Buddhism\n\n- - Drainage and irrigation\n    - [Drainage by wells](https:\/\/en.wikipedia.org\/wiki\/Drainage_by_wells \"Drainage by wells\")\n    - [Shadoof](https:\/\/en.wikipedia.org\/wiki\/Shadoof \"Shadoof\"), an irrigation tool that is used to lift water from a water source onto land or into another waterway or basin\n\n- - Washing\n    - [Lavoir](https:\/\/en.wikipedia.org\/wiki\/Lavoir \"Lavoir\"), public place for washing clothes.\n\n- [Fossil water](https:\/\/en.wikipedia.org\/wiki\/Fossil_water \"Fossil water\")\n\n- [History of water supply and sanitation](https:\/\/en.wikipedia.org\/wiki\/History_of_water_supply_and_sanitation \"History of water supply and sanitation\")\n\n- [Ancient water conservation techniques](https:\/\/en.wikipedia.org\/wiki\/Johad#Similar \"Johad\")\n\n- [Self-supply of water and sanitation](https:\/\/en.wikipedia.org\/wiki\/Self-supply_of_water_and_sanitation \"Self-supply of water and sanitation\")\n\n1. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-1)**\n   Peltenburg, Edgar (2012). \"East Mediterranean water wells of the 9th–7th millennium BC\". In Klimscha, Florian (ed.). *Wasserwirtschaftliche Innovationen im archäologischen Kontext. Von den prähistorischen Anfängen bis zu den Metropolen der Antike*. Rahden\/Westfalia: Leidorf. pp. 69–82\\.\n2. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-2)**\n   Galili, Ehud; Nir, Yaacov (1993). \"The submerged Pre-Pottery Neolithic water well of Atlit-Yam, northern Israel, and its palaeoenvironmental implications\". *The Holocene*. **3** (3): 265–270\\. [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[1993Holoc...3..265G](https:\/\/ui.adsabs.harvard.edu\/abs\/1993Holoc...3..265G). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1177\/095968369300300309](https:\/\/doi.org\/10.1177%2F095968369300300309). [S2CID](https:\/\/en.wikipedia.org\/wiki\/S2CID_\\(identifier\\) \"S2CID (identifier)\") [130032420](https:\/\/api.semanticscholar.org\/CorpusID:130032420).\n3. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-3)**\n   Rybníček, Michal; Kočár, Petr; Muigg, Bernhard; Peška, Jaroslav; Sedláček, Radko; Tegel, Willy; Kolář, Tomáš (2020). [\"World's oldest dendrochronologically dated archaeological wood construction\"](https:\/\/www.sciencedirect.com\/science\/article\/pii\/S0305440320300066). *Journal of Archaeological Science*. **115** 105082. [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[2020JArSc.115j5082R](https:\/\/ui.adsabs.harvard.edu\/abs\/2020JArSc.115j5082R). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1016\/j.jas.2020.105082](https:\/\/doi.org\/10.1016%2Fj.jas.2020.105082). [S2CID](https:\/\/en.wikipedia.org\/wiki\/S2CID_\\(identifier\\) \"S2CID (identifier)\") [213707193](https:\/\/api.semanticscholar.org\/CorpusID:213707193).\n4. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-4)**\n   [\"Kückhovener Brunnen – Dorfgemeinschaft Kückhoven E. V.\"](http:\/\/www.dorfgemeinschaft-kueckhoven.de\/unser-dorf\/kueckhovener-brunnen\/)\n   \n   \\[*[permanent dead link](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Link_rot \"Wikipedia:Link rot\")*\\]\n5. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-5)**\n   Tegel W, Elburg R, Hakelberg D, Stäuble H, Büntgen U (2012). [\"Early Neolithic Water Wells Reveal the World's Oldest Wood Architecture\"](https:\/\/www.ncbi.nlm.nih.gov\/pmc\/articles\/PMC3526582). *PLOS ONE*. **7** (12) e51374. [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[2012PLoSO...751374T](https:\/\/ui.adsabs.harvard.edu\/abs\/2012PLoSO...751374T). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1371\/journal.pone.0051374](https:\/\/doi.org\/10.1371%2Fjournal.pone.0051374). [PMC](https:\/\/en.wikipedia.org\/wiki\/PMC_\\(identifier\\) \"PMC (identifier)\") [3526582](https:\/\/www.ncbi.nlm.nih.gov\/pmc\/articles\/PMC3526582). [PMID](https:\/\/en.wikipedia.org\/wiki\/PMID_\\(identifier\\) \"PMID (identifier)\") [23284685](https:\/\/pubmed.ncbi.nlm.nih.gov\/23284685).\n6. ^ [***a***](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-Kuhn2004_6-0) [***b***](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-Kuhn2004_6-1)\n   Kuhn, Oliver (2004-06-30). [\"Ancient Chinese Drilling\"](https:\/\/csegrecorder.com\/articles\/view\/ancient-chinese-drilling). *Canadian Society of Exploration Geophysicists*. **29** (6).\n7. ^ [***a***](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-Chang2012_7-0) [***b***](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-Chang2012_7-1)\n   Chang, Mingteh (2012). *Forest Hydrology: An Introduction to Water and Forests* (3rd ed.). CRC Press (published November 1, 2012). p. 31. [ISBN](https:\/\/en.wikipedia.org\/wiki\/ISBN_\\(identifier\\) \"ISBN (identifier)\")\n   \n   [978-1-4398-7994-8](https:\/\/en.wikipedia.org\/wiki\/Special:BookSources\/978-1-4398-7994-8 \"Special:BookSources\/978-1-4398-7994-8\")\n   \n   .\n8. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-8)**\n   Koon, Wee Kek (July 25, 2015). [\"How the ancient Chinese looked after their drinking water\"](https:\/\/www.scmp.com\/magazines\/post-magazine\/article\/1843012\/how-ancient-chinese-looked-after-their-drinking-water). *South China Morning Post*.\n9. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-9)**\n   [\"Sakieh explication\/difference vs Sakia\"](http:\/\/www.britannica.com\/eb\/topic-518730\/sakia). *Britannica.com*. Retrieved 2011-12-19.\n10. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-10)**\n    [\"Sakia explication\"](http:\/\/www.britannica.com\/eb\/article-9001226\/sakia#271043.hook). *Britannica.com*. Retrieved 2011-12-19.\n11. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-11)**\n    [\"Stone Age wells found in Cyprus\"](https:\/\/news.bbc.co.uk\/2\/hi\/europe\/8118318.stm). *BBC News*.\n12. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-12)**\n    Ashkenazi, Eli (November 9, 2012). [\"Ancient Well Reveals Secrets of First Jezreel Valley Farmers\"](https:\/\/www.haaretz.com\/israel-news\/ancient-well-reveals-secrets-of-first-jezreel-valley-farmers-1.476288). *Haaretz*.\n13. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-ASTM_13-0)**\n    [\"ASTM International – Standards Worldwide\"](https:\/\/web.archive.org\/web\/20200801082953\/https:\/\/www.astm.org\/COMMIT\/D02\/to1899_index.html). *www.astm.org*. Archived from [the original](https:\/\/www.astm.org\/COMMIT\/D02\/to1899_index.html) on 2020-08-01. Retrieved 2019-02-01.\n14. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-EB1911_14-0)**\n    Joseph P. Riva Jr. and Gordon I. Atwater. [\"petroleum\"](http:\/\/www.britannica.com\/EBchecked\/topic\/454269\/petroleum). *[Encyclopædia Britannica](https:\/\/en.wikipedia.org\/wiki\/Encyclop%C3%A6dia_Britannica \"Encyclopædia Britannica\")*. Retrieved 2008-06-30.\n15. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-15)**\n    [\"Woodingdean Well\"](http:\/\/www.mybrightonandhove.org.uk\/page_id__6948_path__0p115p1224p597p.aspx). 2005. Retrieved 26 Jan 2010.\n16. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-16)**\n    [\"St. Patrick's Well\"](http:\/\/www.umbriatravel.com\/Orvieto\/en\/itineraries_Orvieto.asp). Umbriatravel.com. Retrieved 2011-12-19.\n    \n    \\[*[permanent dead link](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Link_rot \"Wikipedia:Link rot\")*\\]\n17. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-17)** [\"How I drill a Well.\"](https:\/\/books.google.com\/books?id=oiEDAAAAMBAJ&dq=popular+science+1930&pg=-PA77) *Popular Science*, April 1952, pp. 177–181.\n18. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-18)**\n    Association), NKBA (National Kitchen and Bath (2013-10-29). [*Kitchen & Bath Residential Construction and Systems*](https:\/\/books.google.com\/books?id=CVTjAQAAQBAJ&q=Drilled+wells+can+get+water+from+a+much+deeper+level+than+dug+wells+can%E2%80%94often+down+to+several+hundred+metres.&pg=PA178). John Wiley & Sons. [ISBN](https:\/\/en.wikipedia.org\/wiki\/ISBN_\\(identifier\\) \"ISBN (identifier)\")\n    \n    [978-1-118-71104-0](https:\/\/en.wikipedia.org\/wiki\/Special:BookSources\/978-1-118-71104-0 \"Special:BookSources\/978-1-118-71104-0\")\n    \n    .\n19. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-19)**\n    [\"Artesian Water and Artesian Wells \\| U.S. Geological Survey\"](https:\/\/www.usgs.gov\/water-science-school\/science\/artesian-water-and-artesian-wells). *www.usgs.gov*. 2018-10-09. Retrieved 2026-03-23.\n20. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-20)**\n    Arnold, L.R.; Flynn, J.L.; Paschke, S.S. (2009-10-20). [\"Design and installation of a groundwater monitoring-well network in the High Plains aquifer, Colorado\"](https:\/\/pubs.usgs.gov\/publication\/ds456). *USGS Report*. Data Series. U.S. Geological Survey: 5. [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[2009usgs.rept....5A](https:\/\/ui.adsabs.harvard.edu\/abs\/2009usgs.rept....5A). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.3133\/ds456](https:\/\/doi.org\/10.3133%2Fds456). Retrieved 27 May 2024.\n21. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-21)**\n    Du Preez, Michael. [\"ELECTRO-SEISMIC SURVEYS APPLIED TO MODDELING OF GROUNDWATER FLOW SYSTEMS\"](https:\/\/web.archive.org\/web\/20110531163202\/http:\/\/aquamap.co.nz\/uploads\/pdfs\/ELECTRO-SEISMIC%20SURVEYS%20APPLIED%20TO%20MODELING%20OF%20GROUNDWATER%20FLOW.pdf) (PDF). Bloemfontein, South Africa. Archived from [the original](http:\/\/aquamap.co.nz\/uploads\/pdfs\/ELECTRO-SEISMIC%20SURVEYS%20APPLIED%20TO%20MODELING%20OF%20GROUNDWATER%20FLOW.pdf) (PDF) on 31 May 2011. Retrieved 21 April 2011.\n22. ^ [***a***](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-CEH-CID_22-0) [***b***](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-CEH-CID_22-1) [***c***](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-CEH-CID_22-2) [***d***](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-CEH-CID_22-3) [***e***](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-CEH-CID_22-4)\n    Committee on Environmental Health; Committee on Infectious Diseases (2009). [\"Drinking water from private wells and risks to children\"](https:\/\/doi.org\/10.1542%2Fpeds.2009-0751). *[Pediatrics](https:\/\/en.wikipedia.org\/wiki\/Pediatrics_\\(journal\\) \"Pediatrics (journal)\")*. **123** (6): 1599–1605\\. [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1542\/peds.2009-0751](https:\/\/doi.org\/10.1542%2Fpeds.2009-0751). [PMID](https:\/\/en.wikipedia.org\/wiki\/PMID_\\(identifier\\) \"PMID (identifier)\") [19482772](https:\/\/pubmed.ncbi.nlm.nih.gov\/19482772).\n23. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-23)**\n    Wiebe, Andrew J.; Rudolph, David L.; Pasha, Ehsan; Brook, Jacqueline M.; Christie, Mike; Menkveld, Paul G. (2021). [\"Impacts of Event-Based Recharge on the Vulnerability of Public Supply Wells\"](https:\/\/doi.org\/10.3390%2Fsu13147695). *Sustainability*. **13** (14): 7695. [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[2021Sust...13.7695W](https:\/\/ui.adsabs.harvard.edu\/abs\/2021Sust...13.7695W). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.3390\/su13147695](https:\/\/doi.org\/10.3390%2Fsu13147695). [ISSN](https:\/\/en.wikipedia.org\/wiki\/ISSN_\\(identifier\\) \"ISSN (identifier)\") [2071-1050](https:\/\/search.worldcat.org\/issn\/2071-1050).\n24. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-24)**\n    Association, American Water Works (2003). [*Water Sources*](https:\/\/books.google.com\/books?id=iOIdnO03cgEC&q=Chemical+contamination+is+a+common+problem+with+groundwater&pg=PA141). American Water Works Association. [ISBN](https:\/\/en.wikipedia.org\/wiki\/ISBN_\\(identifier\\) \"ISBN (identifier)\")\n    \n    [978-1-58321-229-5](https:\/\/en.wikipedia.org\/wiki\/Special:BookSources\/978-1-58321-229-5 \"Special:BookSources\/978-1-58321-229-5\")\n    \n    .\n25. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-25)**\n    Meulemans, C. C. E. (1987-09-01). \"The Basic Principles of UV–Disinfection of Water\". *Ozone: Science & Engineering*. **9** (4): 299–313\\. [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[1987OzSE....9..299M](https:\/\/ui.adsabs.harvard.edu\/abs\/1987OzSE....9..299M). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1080\/01919518708552146](https:\/\/doi.org\/10.1080%2F01919518708552146). [ISSN](https:\/\/en.wikipedia.org\/wiki\/ISSN_\\(identifier\\) \"ISSN (identifier)\") [0191-9512](https:\/\/search.worldcat.org\/issn\/0191-9512).\n26. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-26)**\n    [\"Soil salination by placement of water wells mentioned in India\"](https:\/\/web.archive.org\/web\/20090522010539\/http:\/\/ngm.nationalgeographic.com\/2009\/06\/cheap-food\/bourne-text\/1). Ngm.nationalgeographic.com. 2002-10-17. Archived from [the original](http:\/\/ngm.nationalgeographic.com\/2009\/06\/cheap-food\/bourne-text\/1) on May 22, 2009. Retrieved 2011-12-19.\n27. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-27)**\n    [\"Practical Answers – Handpumps\"](http:\/\/practicalaction.org\/practicalanswers\/product_info.php?products_id=198). Practicalaction.org. Retrieved 2011-12-19.\n28. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-28)**\n    [\"Treadle pump\"](http:\/\/dev.practicalaction.org\/?id=appeal_nepalpump). Dev.practicalaction.org. Retrieved 2011-12-19.\n29. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-29)**\n    Famiglietti, James S.; Ferguson, Grant (23 April 2021). [\"The hidden crisis beneath our feet\"](https:\/\/www.science.org\/doi\/10.1126\/science.abh2867). *Science*. **372** (6540): 344–345\\. [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[2021Sci...372..344F](https:\/\/ui.adsabs.harvard.edu\/abs\/2021Sci...372..344F). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1126\/science.abh2867](https:\/\/doi.org\/10.1126%2Fscience.abh2867). [PMID](https:\/\/en.wikipedia.org\/wiki\/PMID_\\(identifier\\) \"PMID (identifier)\") [33888627](https:\/\/pubmed.ncbi.nlm.nih.gov\/33888627). [S2CID](https:\/\/en.wikipedia.org\/wiki\/S2CID_\\(identifier\\) \"S2CID (identifier)\") [233353241](https:\/\/api.semanticscholar.org\/CorpusID:233353241). Retrieved 10 May 2021.\n30. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-30)**\n    [\"The largest assessment of global groundwater wells finds many are at risk of drying up\"](https:\/\/www.sciencedaily.com\/releases\/2021\/04\/210423130101.htm). *ScienceDaily*. Retrieved 10 May 2021.\n31. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-31)**\n    Jasechko, Scott; Perrone, Debra (23 April 2021). [\"Global groundwater wells at risk of running dry\"](https:\/\/www.science.org\/doi\/10.1126\/science.abc2755). *Science*. **372** (6540): 418–421\\. [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[2021Sci...372..418J](https:\/\/ui.adsabs.harvard.edu\/abs\/2021Sci...372..418J). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1126\/science.abc2755](https:\/\/doi.org\/10.1126%2Fscience.abc2755). [ISSN](https:\/\/en.wikipedia.org\/wiki\/ISSN_\\(identifier\\) \"ISSN (identifier)\") [0036-8075](https:\/\/search.worldcat.org\/issn\/0036-8075). [PMID](https:\/\/en.wikipedia.org\/wiki\/PMID_\\(identifier\\) \"PMID (identifier)\") [33888642](https:\/\/pubmed.ncbi.nlm.nih.gov\/33888642). [S2CID](https:\/\/en.wikipedia.org\/wiki\/S2CID_\\(identifier\\) \"S2CID (identifier)\") [233353207](https:\/\/api.semanticscholar.org\/CorpusID:233353207). Retrieved 10 May 2021.\n32. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-Burr_32-0)**\n    Burr, Thomas Benge (1766). [*The History of Tunbridge Wells*](https:\/\/web.archive.org\/web\/20210131221739\/https:\/\/theweald.org\/d10.asp?BookId=burr000). London. Archived from [the original](http:\/\/theweald.org\/bk.asp?bookid=burr000) on 2021-01-31. Retrieved 2019-10-09.\n33. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-russo273277_33-0)**\n    [Russo, Lucio](https:\/\/en.wikipedia.org\/wiki\/Lucio_Russo \"Lucio Russo\") (2004). *The Forgotten Revolution*. Berlin: Springer. pp. 273–277\\.\n34. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-34)**\n    Bromiley, Geoffrey W. (1982), *International Standard Bible Encyclopedia: E-J*, Wm. B. Eerdmans Publishing, p. 955, [ISBN](https:\/\/en.wikipedia.org\/wiki\/ISBN_\\(identifier\\) \"ISBN (identifier)\")\n    \n    [978-0-8028-3782-0](https:\/\/en.wikipedia.org\/wiki\/Special:BookSources\/978-0-8028-3782-0 \"Special:BookSources\/978-0-8028-3782-0\")\n35. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-Humboldt_35-0)**\n    [\"Well Flow Equations\"](https:\/\/geology.humboldt.edu\/courses\/geology556\/556_handouts\/well_flow_equations.pdf) (PDF). Cal Poly Humboldt, Department of Geology. Retrieved June 13, 2022.\n36. **[^](https:\/\/en.wikipedia.org\/wiki\/Well#cite_ref-Inspectapedia_36-0)**\n    [\"How Much Water Can the Well Deliver\"](https:\/\/inspectapedia.com\/water\/Well_Flow_Rate.php). Inspectapedia. Retrieved June 13, 2022.\n\n- Driscoll, F. (1986). *Groundwater and Wells*. [St. Paul](https:\/\/en.wikipedia.org\/wiki\/St._Paul,_MN \"St. Paul, MN\"): Johnson Filtration Systems. [ISBN](https:\/\/en.wikipedia.org\/wiki\/ISBN_\\(identifier\\) \"ISBN (identifier)\")\n  \n  [978-0-9616456-0-1](https:\/\/en.wikipedia.org\/wiki\/Special:BookSources\/978-0-9616456-0-1 \"Special:BookSources\/978-0-9616456-0-1\")\n  \n  .\n- Raymond Rowles (1995). *Drilling for Water* (2nd ed.). Avebury, Cranfield University. [ISBN](https:\/\/en.wikipedia.org\/wiki\/ISBN_\\(identifier\\) \"ISBN (identifier)\")\n  \n  [1-85628-984-2](https:\/\/en.wikipedia.org\/wiki\/Special:BookSources\/1-85628-984-2 \"Special:BookSources\/1-85628-984-2\")\n  \n  .\n\n[![Wikisource logo](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/4\/4c\/Wikisource-logo.svg\/40px-Wikisource-logo.svg.png)](https:\/\/en.wikipedia.org\/wiki\/File:Wikisource-logo.svg)\n\n- [Sustainable Groundwater Development theme of the Rural Water Supply Network (RWSN)](http:\/\/www.rural-water-supply.net\/en\/sustainable-groundwater-management)\n- [Water Portal – Akvopedia](http:\/\/akvopedia.org\/wiki\/Water_Portal) [Archived](https:\/\/web.archive.org\/web\/20141018231204\/http:\/\/akvopedia.org\/wiki\/Water_Portal) 2014-10-18 at the [Wayback Machine](https:\/\/en.wikipedia.org\/wiki\/Wayback_Machine \"Wayback Machine\")\n- [Sustainable Sanitation and Water Management Toolbox](http:\/\/www.sswm.info\/)\n- [U.S. Centers for Disease Control and Prevention (CDC) Healthy Water – Water Wells](https:\/\/www.cdc.gov\/healthywater\/drinking\/private\/wells\/index.html) Site covering well basics, guidelines for proper siting and location of wells to avoid contamination, well testing, diseases related to wells, emergency well treatment and other topics.\n- [US Geological Survey – Ground water: Wells](https:\/\/ga.water.usgs.gov\/edu\/earthgwwells.html)\n- [US Geological Survey – Water Science Pictures Flowing Artesian Well](https:\/\/ga.water.usgs.gov\/edu\/gwartesian.html)\n- [Drilling wells 18 extremely useful questions and answers](https:\/\/www.euforaje.ro\/foraje-puturi\/)\n- [American Ground Water Trust](http:\/\/agwt.org\/)\n- [Lifewater International Technical Library](http:\/\/www.lifewater.org\/resources\/ground_water.html#GW) [Archived](https:\/\/web.archive.org\/web\/20130616030412\/http:\/\/www.lifewater.org\/resources\/ground_water.html#GW) 2013-06-16 at the [Wayback Machine](https:\/\/en.wikipedia.org\/wiki\/Wayback_Machine \"Wayback Machine\")\n- [Well Construction Technical Resources for NGOs](http:\/\/www.watersanitationhygiene.org\/References\/Technical%20Resources%20-%20Wells.htm)","meta_canonical":null}

3. Robots.txt Check

Query:

Response:

4. Spam/Ban Check

Query:

Response:

5. Seen Status Check

ℹ️ Skipped - page is already crawled

📄

INDEXABLE

✅

CRAWLED

12 hours ago

🤖

ROBOTS ALLOWED

Page Info Filters

Filter	Status	Condition	Details
HTTP status	PASS	`download_http_code = 200`	HTTP 200
Age cutoff	PASS	`download_stamp > now() - 6 MONTH`	0 months ago (distributed domain, exempt)
History drop	PASS	`isNull(history_drop_reason)`	No drop reason
Spam/ban	PASS	`fh_dont_index != 1 AND ml_spam_score = 0`	ml_spam_score=0
Canonical	PASS	`meta_canonical IS NULL OR = '' OR = src_unparsed`	Not set

Page Details

Property	Value
URL	https://en.wikipedia.org/wiki/Well
Last Crawled	2026-04-11 20:38:22 (12 hours ago)
First Indexed	2015-06-18 14:01:17 (10 years ago)
HTTP Status Code	200
Meta Title	Well - Wikipedia
Meta Description	null
Meta Canonical	null
Boilerpipe Text	"Village pump" redirects here. For the set of Wikipedia discussion pages, see Wikipedia:Village pump . A dug well in a village in Faryab Province , Afghanistan The difference between a well and a cistern is in the source of the water: a cistern collects rainwater whereas a well draws from groundwater . A well is an excavation or structure created on the earth by digging , driving, or drilling to access liquid resources, usually water . The oldest and most common kind of well is a water well, to access groundwater in underground aquifers . The well water is drawn up by a pump , or using containers, such as buckets that are raised mechanically or by hand. Water can also be injected back into the aquifer through the well. Wells were first constructed at least eight thousand years ago and historically vary in construction from a sediment of a dry watercourse to the qanats of Iran, and the stepwells and sakiehs of India. Placing a lining in the well shaft helps create stability, and linings of wood or wickerwork date back at least as far as the Iron Age . Wells have traditionally been sunk by hand digging, as is still the case in rural areas of the developing world. These wells are inexpensive and low-tech as they use mostly manual labour, and the structure can be lined with brick or stone as the excavation proceeds. A more modern method called caissoning uses pre-cast reinforced concrete well rings that are lowered into the hole. Driven wells can be created in unconsolidated material with a well hole structure, which consists of a hardened drive point and a screen of perforated pipe, after which a pump is installed to collect the water. Deeper wells can be excavated by hand drilling methods or machine drilling, using a bit in a borehole . Drilled wells are usually cased with a factory-made pipe composed of steel or plastic. Drilled wells can access water at much greater depths than dug wells. Two broad classes of well are shallow or unconfined wells completed within the uppermost saturated aquifer at that location, and deep or confined wells, sunk through an impermeable stratum into an aquifer beneath. A collector well can be constructed adjacent to a freshwater lake or stream with water percolating through the intervening material. The site of a well can be selected by a hydrogeologist , or groundwater surveyor. Water may be pumped or hand drawn. Impurities from the surface can easily reach shallow sources and contamination of the supply by pathogens or chemical contaminants needs to be avoided. Well water typically contains more minerals in solution than surface water and may require treatment before being potable. Soil salination can occur as the water table falls and the surrounding soil begins to dry out. Another environmental problem is the potential for methane to seep into the water. Camel drawing water from a well, Djerba island, Tunisia, 1960 Very early Neolithic wells are known from the Eastern Mediterranean . [ 1 ] The oldest reliably dated well is from the pre-pottery neolithic (PPN) site of Kissonerga-Mylouthkia on Cyprus . At around 8400 BC a shaft (well 116) of circular diameter was driven through limestone to reach an aquifer at a depth of 8 metres (26 ft). Well 2070 from Kissonerga-Mylouthkia, dating to the late PPN, reaches a depth of 13 metres (43 ft). Other slightly younger wells are known from this site and from neighbouring Parekklisha-Shillourokambos. A first stone lined [ 2 ] well of 5.5 metres (18 ft) depth is documented from a drowned final PPN (c. 7000 BC) site at 'Atlit-Yam off the coast near modern Haifa in Israel . Neolithic Linear Pottery culture well, 5300 BC, Erkelenz , Germany Wood-lined wells are known from the early Neolithic Linear Pottery culture , for example in Ostrov, Czech Republic, dated 5265 BC, [ 3 ] Kückhoven (an outlying centre of Erkelenz ), dated 5300 BC, [ 4 ] and Eythra in Schletz (an outlying centre of Asparn an der Zaya ) in Austria , dated 5200 BC. [ 5 ] The Neolithic Chinese discovered and made extensive use of deep drilled groundwater for drinking. [ citation needed ] The Chinese text The Book of Changes , originally a divination text of the Western Zhou dynasty (1046 -771 BC), contains an entry describing how the ancient Chinese maintained their wells and protected their sources of water. [ 6 ] A well excavated at the Hemedu excavation site was believed to have been built during the neolithic era. [ 7 ] The well was cased by four rows of logs with a square frame attached to them at the top of the well. 60 additional tile wells southwest of Beijing are also believed to have been built around 600 BC for drinking and irrigation. [ 7 ] [ 8 ] A Chinese ceramic model of a well with a water pulley system, excavated from a tomb of the Han dynasty (202 BC – 220 AD) period In Egypt , shadoofs and sakias are used. [ 9 ] [ 10 ] The sakia is much more efficient, as it can bring up water from a depth of 10 metres (versus the 3 metres of the shadoof). The sakia is the Egyptian version of the noria . Some of the world's oldest known wells, located in Cyprus, date to 7000–8,500 BC. [ 11 ] Two wells from the Neolithic period, around 6500 BC, have been discovered in Israel. One is in Atlit, on the northern coast of Israel, and the other is in the Jezreel Valley. [ 12 ] Wells for other purposes came along much later, historically. The first recorded salt well was dug in the Sichuan province of China around 2,250 years ago. This was the first time that ancient water well technology was applied successfully for the exploitation of salt, and marked the beginning of Sichuan's salt drilling industry. [ 6 ] The earliest known oil wells were also drilled in China, in 347 CE. These wells had depths of up to about 240 metres (790 ft) and were drilled using bits attached to bamboo poles. [ 13 ] The oil was burned to evaporate brine and produce salt . By the 10th century, extensive bamboo pipelines connected oil wells with salt springs. The ancient records of China and Japan are said to contain many allusions to the use of natural gas for lighting and heating. Petroleum was known as Burning water in Japan in the 7th century. [ 14 ] Water well near Simaisma , eastern Qatar Leather bucket used for the water well Well, Historical Village, Bhaini Sahib, Ludhiana , Punjab , India View into a hand-dug well cased with concrete rings. Ouelessebougou , Mali. A dug well in a village in Kerala , India Well with a flower bag-shaped wall and podium Until recent centuries, all artificial wells were pumpless hand-dug wells of varying degrees of sophistication, and they remain a very important source of potable water in some rural developing areas, where they are routinely dug and used today. Their indispensability has produced a number of literary references, literal and figurative, including the reference to the incident of Jesus meeting a woman at Jacob 's well ( John 4:6) in the Bible and the " Ding Dong Bell " nursery rhyme about a cat in a well. Hand-dug wells are excavations with diameters large enough to accommodate one or more people with shovels digging down to below the water table . The excavation is braced horizontally to avoid landslide or erosion endangering the people digging. They can be lined with stone or brick; extending this lining upwards above the ground surface to form a wall around the well serves to reduce both contamination and accidental falls into the well. A more modern method called caissoning uses reinforced concrete or plain concrete pre-cast well rings that are lowered into the hole. A well-digging team digs under a cutting ring and the well column slowly sinks into the aquifer , whilst protecting the team from collapse of the well bore . Hand-dug wells are inexpensive and low tech (compared to drilling) and they use mostly manual labour to access groundwater in rural locations of developing countries. They may be built with a high degree of community participation, or by local entrepreneurs who specialize in hand-dug wells. They have been successfully excavated to 60 metres (200 ft). They have low operational and maintenance costs, in part because water can be extracted by hand, without a pump. The water often comes from an aquifer or groundwater, and can be easily deepened, which may be necessary if the ground water level drops, by telescoping the lining further down into the aquifer. The yield of existing hand dug wells may be improved by deepening or introducing vertical tunnels or perforated pipes. Drawbacks to hand-dug wells are numerous. It can be impractical to hand dig wells in areas where hard rock is present, and they can be time-consuming to dig and line even in favourable areas. Because they exploit shallow aquifers, the well may be susceptible to yield fluctuations and possible contamination from surface water, including sewage. Hand dug well construction generally requires the use of a well trained construction team, and the capital investment for equipment such as concrete ring moulds, heavy lifting equipment, well shaft formwork, motorized de-watering pumps, and fuel can be large for people in developing countries. Construction of hand dug wells can be dangerous due to collapse of the well bore, falling objects and asphyxiation, including from dewatering pump exhaust fumes. The Woodingdean Water Well , hand-dug between 1858 and 1862, is the deepest hand-dug well at 392 metres (1,285 ft). [ 15 ] The Big Well in Greensburg, Kansas , is billed as the world's largest hand-dug well, at 109 feet (33 m) deep and 32 feet (9.8 m) in diameter. However, the Well of Joseph in the Cairo Citadel at 280 feet (85 m) deep and the Pozzo di San Patrizio (St. Patrick's Well) built in 1527 in Orvieto, Italy , at 61 metres (200 ft) deep by 13 metres (43 ft) wide [ 16 ] are both larger by volume. Driven wells may be very simply created in unconsolidated material with a well hole structure , which consists of a hardened drive point and a screen (perforated pipe). The point is simply hammered into the ground, usually with a tripod and driver , with pipe sections added as needed. A driver is a weighted pipe that slides over the pipe being driven and is repeatedly dropped on it. When groundwater is encountered, the well is washed of sediment and a pump installed. [ 17 ] Drilled wells are constructed using various types of drilling machines, such as top-head rotary, table rotary, or cable tool, which all use drilling stems that rotate to cut into the formation, thus the term "drilling." Drilled wells can be excavated by simple hand drilling methods (augering, sludging, jetting, driving, hand percussion) or machine drilling (auger, rotary, percussion, down the hole hammer). Deep rock rotary drilling method is most common. Rotary can be used in 90% of formation types (consolidated). Drilled wells can get water from a much deeper level than dug wells can − often down to several hundred metres. [ 18 ] Drilled wells with electric pumps are used throughout the world, typically in rural or sparsely populated areas, though many urban areas are supplied partly by municipal wells. Most shallow well drilling machines are mounted on large trucks, trailers, or tracked vehicle carriages. Water wells typically range from 3 to 18 metres (10–60 ft) deep, but in some areas it can go deeper than 900 metres (3,000 ft). [ citation needed ] Cable tool water well drilling rig in Kimball, West Virginia Israeli geologist Leo Picard (white shirt) inspects a drilled water well outside the depopulated Palestinian village of Bayt Naqquba Rotary drilling machines use a segmented steel drilling string, typically made up of 3m (10ft), 6 m (20 ft) to 8m (26ft) sections of steel tubing that are threaded together, with a bit or other drilling device at the bottom end. Some rotary drilling machines are designed to install (by driving or drilling) a steel casing into the well in conjunction with the drilling of the actual bore hole. Air and/or water is used as a circulation fluid to displace cuttings and cool bits during the drilling. Another form of rotary-style drilling, termed mud rotary , makes use of a specially made mud, or drilling fluid, which is constantly being altered during the drill so that it can consistently create enough hydraulic pressure to hold the side walls of the bore hole open, regardless of the presence of a casing in the well. Typically, boreholes drilled into solid rock are not cased until after the drilling process is completed, regardless of the machinery used. The oldest form of drilling machinery is the cable tool , still used today. Specifically designed to raise and lower a bit into the bore hole, the spudding of the drill causes the bit to be raised and dropped onto the bottom of the hole, and the design of the cable causes the bit to twist at approximately 1 ⁄ 4 revolution per drop, thereby creating a drilling action. Unlike rotary drilling, cable tool drilling requires the drilling action to be stopped so that the bore hole can be bailed or emptied of drilled cuttings. Cable tool drilling rigs are rare as they tend to be 10x slower to drill through materials compared to similar diameter rotary air or rotary mud equipped rigs. Drilled wells are usually cased with a factory-made pipe, typically steel (in air rotary or cable tool drilling) or plastic / PVC (in mud rotary wells, also present in wells drilled into solid rock). The casing is constructed by welding, either chemically or thermally, segments of casing together. If the casing is installed during the drilling, most drills will drive the casing into the ground as the bore hole advances, while some newer machines will actually allow for the casing to be rotated and drilled into the formation in a similar manner as the bit advancing just below. PVC or plastic is typically solvent welded and then lowered into the drilled well, vertically stacked with their ends nested and either glued or splined together. The sections of casing are usually 6 metres (20 ft) or more in length, and 4 to 12 in (10 to 30 cm) in diameter, depending on the intended use of the well and local groundwater conditions. Surface contamination of wells in the United States is typically controlled by the use of a surface seal . A large hole is drilled to a predetermined depth or to a confining formation (clay or bedrock, for example), and then a smaller hole for the well is completed from that point forward. The well is typically cased from the surface down into the smaller hole with a casing that is the same diameter as that hole. The annular space between the large bore hole and the smaller casing is filled with bentonite clay , concrete, or other sealant material. This creates an impermeable seal from the surface to the next confining layer that keeps contaminants from traveling down the outer sidewalls of the casing or borehole and into the aquifer . In addition, wells are typically capped with either an engineered well cap or seal that vents air through a screen into the well, but keeps insects, small animals, and unauthorized persons from accessing the well. At the bottom of wells, based on formation, a screening device, filter pack, slotted casing, or open bore hole is left to allow the flow of water into the well. Constructed screens are typically used in unconsolidated formations (sands, gravels, etc.), allowing water and a percentage of the formation to pass through the screen. Allowing some material to pass through creates a large area filter out of the rest of the formation, as the amount of material present to pass into the well slowly decreases and is removed from the well. Rock wells are typically cased with a PVC liner/casing and screen or slotted casing at the bottom, this is mostly present just to keep rocks from entering the pump assembly. Some wells use a filter pack method, where an undersized screen or slotted casing is placed inside the well and a filter medium is packed around the screen, between the screen and the borehole or casing. This allows the water to be filtered of unwanted materials before entering the well and pumping zone. An automated water well system powered by a jet-pump An automated water well system powered by a submersible pump A water well system with a cistern A water well system with a pressurized cistern A section of a stainless steel screen well Water well types There are two broad classes of drilled-well types, based on the type of aquifer the well is in: Shallow or unconfined wells are completed in the uppermost saturated aquifer at that location (the upper unconfined aquifer). [ citation needed ] Deep or confined wells are sunk through an impermeable stratum into an aquifer that is sandwiched between two impermeable strata (aquitards or aquicludes). The majority of deep aquifers are classified as artesian because the hydraulic head in a confined well is higher than the level of the top of the aquifer. If the hydraulic head in a confined well is higher than the land surface it is a "flowing" artesian well (named after Artois in France ). [ 19 ] An old-fashioned water well in the countryside of Utajärvi , Finland A special type of water well may be constructed adjacent to freshwater lakes or streams. Commonly called a collector well but sometimes referred to by the trade name Ranney well or Ranney collector , this type of well involves sinking a caisson vertically below the top of the aquifer and then advancing lateral collectors out of the caisson and beneath the surface water body. Pumping from within the caisson induces infiltration of water from the surface water body into the aquifer, where it is collected by the collector well laterals and conveyed into the caisson where it can be pumped to the ground surface. [ citation needed ] Two additional broad classes of well types may be distinguished, based on the use of the well: production or pumping wells , are large diameter (greater than 15 cm in diameter) cased (metal, plastic, or concrete) water wells, constructed for extracting water from the aquifer by a pump (if the well is not artesian ). [ citation needed ] Schematic diagram of a groundwater monitoring well monitoring wells or piezometers , are often smaller diameter wells used to monitor the hydraulic head or sample the groundwater for chemical constituents. Piezometers are monitoring wells completed over a very short section of aquifer. Monitoring wells can also be completed at multiple levels, allowing discrete samples or measurements to be made at different vertical elevations at the same map location. [ 20 ] A water well constructed for pumping groundwater can be used passively as a monitoring well and a small diameter well can be pumped, but this distinction by use is common. [ citation needed ] Before excavation, information about the geology, water table depth, seasonal fluctuations, recharge area and rate should be found if possible. This work can be done by a hydrogeologist , or a groundwater surveyor using a variety of tools including electro-seismic surveying, [ 21 ] any available information from nearby wells, geologic maps, and sometimes geophysical imaging . These professionals provide advice that is almost as accurate a driller who has experience and knowledge of nearby wells/bores and the most suitable drilling technique based on the expected target depth. Waterborne diseases can be spread via a well which is contaminated with fecal pathogens from pit latrines . Man cleaning a well in Yaoundé , Cameroon Hand pump to pump water from a well in a village near Chennai in India, where the well water might be polluted by nearby pit latrines . Shallow pumping wells can often supply drinking water at a very low cost. However, impurities from the surface easily reach shallow sources, which leads to a greater risk of contamination for these wells compared to deeper wells. Contaminated wells can lead to the spread of various waterborne diseases . Dug and driven wells are relatively easy to contaminate; for instance, most dug wells are unreliable in the majority of the United States. [ 22 ] Some research has found that, in cold regions, changes in river flow and flooding caused by extreme rainfall or snowmelt can degrade well water quality. [ 23 ] Most of the bacteria , viruses , parasites , and fungi that contaminate well water comes from fecal material from humans and other animals. Common bacterial contaminants include E. coli , Salmonella , Shigella , and Campylobacter jejuni . Common viral contaminants include norovirus , sapovirus , rotavirus , enteroviruses , and hepatitis A and E . Parasites include Giardia lamblia , Cryptosporidium , Cyclospora cayetanensis , and microsporidia . [ 22 ] Chemical contamination [ edit ] Chemical contamination is a common problem with groundwater. [ 24 ] Nitrates from sewage , sewage sludge or fertilizer are a particular problem for babies and young children. Pollutant chemicals include pesticides and volatile organic compounds from gasoline , dry-cleaning , the fuel additive methyl tert-butyl ether (MTBE), and perchlorate from rocket fuel, airbag inflators, and other artificial and natural sources. [ citation needed ] Several minerals are also contaminants, including lead leached from brass fittings or old lead pipes, chromium VI from electroplating and other sources, naturally occurring arsenic , radon , and uranium —all of which can cause cancer—and naturally occurring fluoride , which is desirable in low quantities to prevent tooth decay , but can cause dental fluorosis in higher concentrations. [ 22 ] Some chemicals are commonly present in water wells at levels that are not toxic, but can cause other problems. Calcium and magnesium cause what is known as hard water , which can precipitate and clog pipes or burn out water heaters. Iron and manganese can appear as dark flecks that stain clothing and plumbing, and can promote the growth of iron and manganese bacteria that can form slimy black colonies that clog pipes. [ 22 ] The quality of the well water can be significantly increased by lining the well, sealing the well head, fitting a self-priming hand pump, constructing an apron, ensuring the area is kept clean and free from stagnant water and animals, moving sources of contamination ( pit latrines , garbage pits, on-site sewer systems ) and carrying out hygiene education. The well should be cleaned with 1% chlorine solution after construction and periodically every 6 months. [ citation needed ] Well holes should be covered to prevent loose debris, animals, animal excrement, and wind-blown foreign matter from falling into the hole and decomposing. The cover should be able to be in place at all times, including when drawing water from the well. A suspended roof over an open hole helps to some degree, but ideally the cover should be tight fitting and fully enclosing, with only a screened air vent. [ citation needed ] Minimum distances and soil percolation requirements between sewage disposal sites and water wells need to be observed. Rules regarding the design and installation of private and municipal septic systems take all these factors into account so that nearby drinking water sources are protected. Education of the general population in society also plays an important role in protecting drinking water. [ citation needed ] Cleanup of contaminated groundwater tends to be very costly. Effective remediation of groundwater is generally very difficult. Contamination of groundwater from surface and subsurface sources can usually be dramatically reduced by correctly centering the casing during construction and filling the casing annulus with an appropriate sealing material. The sealing material (grout) should be placed from immediately above the production zone back to surface, because, in the absence of a correctly constructed casing seal, contaminated fluid can travel into the well through the casing annulus. Centering devices are important (usually one per length of casing or at maximum intervals of 9 m) to ensure that the grouted annular space is of even thickness. [ citation needed ] Upon the construction of a new test well, it is considered best practice to invest in a complete battery of chemical and biological tests on the well water in question. Point-of-use treatment is available for individual properties and treatment plants are often constructed for municipal water supplies that suffer from contamination. Most of these treatment methods involve the filtration of the contaminants of concern, and additional protection may be garnered by installing well-casing screens only at depths where contamination is not present. [ citation needed ] Wellwater for personal use is often filtered with reverse osmosis water processors; this process can remove very small particles. A simple, effective way of killing microorganisms is to bring the water to a full boil for one to three minutes, depending on location. A household well contaminated by microorganisms can initially be treated by shock chlorination using bleach, generating concentrations hundreds of times greater than found in community water systems; however, this will not fix any structural problems that led to the contamination and generally requires some expertise and testing for effective application. [ 22 ] After the filtration process, it is common to implement an ultraviolet (UV) system to kill pathogens in the water. UV light affects the DNA of the pathogen by UV-C photons breaking through the cell wall. UV disinfection has been gaining popularity in the past decades as it is a chemical-free method of water treatment. [ 25 ] Environmental problems [ edit ] A risk with the placement of water wells is soil salination which occurs when the water table of the soil begins to drop and salt begins to accumulate as the soil begins to dry out. [ 26 ] Another environmental problem that is very prevalent in water well drilling is the potential for methane to seep through. The potential for soil salination is a large risk when choosing the placement of water wells. Soil salination is caused when the water table of the soil drops over time and salt begins to accumulate. In turn, the increased amount of salt begins to dry the soil out. The increased level of salt in the soil can result in the degradation of soil and can be very harmful to vegetation. [ citation needed ] Methane , an asphyxiant, is a chemical compound that is the main component of natural gas. When methane is introduced into a confined space, it displaces oxygen, reducing oxygen concentration to a level low enough to pose a threat to humans and other aerobic organisms but still high enough for a risk of spontaneous or externally caused explosion. This potential for explosion is what poses such a danger in regards to the drilling and placement of water wells. [ citation needed ] Low levels of methane in drinking water are not considered toxic. When methane seeps into a water supply, it is commonly referred to as "methane migration". This can be caused by old natural gas wells near water well systems becoming abandoned and no longer monitored. [ citation needed ] Lately, [ when? ] however, the described wells/pumps are no longer very efficient and can be replaced by either handpumps or treadle pumps . Another alternative is the use of self-dug wells, electrical deep-well pumps (for higher depths). Appropriate technology organizations as Practical Action are now [ when? ] supplying information on how to build/set-up ( DIY ) handpumps and treadle pumps in practice. [ 27 ] [ 28 ] PFAS/PFOS Fire fighting foam [ edit ] Per- and polyfluoroalkyl substances ( PFAS or PFASs ) are a group of synthetic organofluorine chemical compounds that have multiple fluorine atoms attached to an alkyl chain. PFAS are a group of "forever chemicals" that spread very quickly and very far in ground water polluting it permanently. Water wells near certain airports where any foam fire fighting or training activities occurred up to 2010 are likely to be contaminated by PFAS. A study concluded that of ~39 million groundwater wells 9-20% are at high risk of running dry if local groundwater levels decline by less than five meters, or – as with many areas and possibly more than half of major aquifers [ 29 ] – continue to decline. [ 30 ] [ 31 ] [ further explanation needed ] Society and culture [ edit ] Water use, Tacuinum Sanitatis , Biblioteca Casanatense (14th century) Springs and wells have had cultural significance since prehistoric times, leading to the foundation of towns such as Wells and Bath in Somerset . Interest in health benefits led to the growth of spa towns including many with wells in their name, examples being Llandrindod Wells and Royal Tunbridge Wells . [ 32 ] Eratosthenes is sometimes claimed to have used a well in his calculation of the Earth's circumference ; however, this is just a simplification used in a shorter explanation of Cleomedes , since Eratosthenes had used a more elaborate and precise method. [ 33 ] Many incidents in the Bible take place around wells, such as the finding of a wife for Isaac in Genesis and Jesus 's talk with the Samaritan woman in the Gospels . [ 34 ] A simple model for water well recovery [ edit ] Diagram of a water well partially filled to level z with the top of the aquifer at z T For a well with impermeable walls, the water in the well is resupplied from the bottom of the well. The rate at which water flows into the well will depend on the pressure difference between the ground water at the well bottom and the well water at the well bottom. The pressure of a column of water of height z will be equal to the weight of the water in the column divided by the cross-sectional area of the column, so the pressure of the ground water a distance z T below the top of the water table will be: where ρ is the mass density of the water and g is the acceleration due to gravity. When the water in the well is below the water table level, the pressure at the bottom of the well due to the water in the well will be less than P g and water will be forced into the well. Referring to the diagram, if z is the distance from the bottom of the well to the well water level and z T is the distance from the bottom of the well to the top of the water table, the pressure difference will be: Applying Darcy's law , the volume rate ( F ) at which water is forced into the well will be proportional to this pressure difference: where R is the resistance to the flow, which depends on the well cross section, the pressure gradient at the bottom of the well, and the characteristics of the substrate at the well bottom. (e.g., porosity). The volume flow rate into the well can be written as a function of the rate of change of the well water level: Combining the above three equations yields a simple differential equation in z : which may be solved: where z 0 is the well water level at time t=0 and τ is the well time constant: Note that if dz/dt for a depleted well can be measured, it will be equal to and the time constant τ can be calculated. According to the above model, it will take an infinite amount of time for a well to fully recover, but if we consider a well that is 99% recovered to be "practically" recovered, the time for a well to practically recover from a level at z will be: For a well that is fully depleted ( z=0 ) it would take a time of about 4.6 τ to practically recover. The above model does not take into account the depletion of the aquifer due to the pumping which lowered the well water level (See aquifer test and groundwater flow equation ). Also, practical wells may have impermeable walls only up to, but not including the bedrock, which will give a larger surface area for water to enter the well. [ 35 ] [ 36 ] Types of ancient wells Brick-lined well Castle well , for use in the castle Cistern , ancient Greek Stepwell , ancient India Modern construction techniques Baptist well drilling , simple technique Rodriguez well , for harvesting drinking water in polar regions Spring supply , piped water supply from the well Uses Holy well , sacred wells in various religions Abraham's well , sacred well in Israel Ghat , sacred in Hinduism and Buddhism Drainage and irrigation Drainage by wells Shadoof , an irrigation tool that is used to lift water from a water source onto land or into another waterway or basin Washing Lavoir , public place for washing clothes. Fossil water History of water supply and sanitation Ancient water conservation techniques Self-supply of water and sanitation ^ Peltenburg, Edgar (2012). "East Mediterranean water wells of the 9th–7th millennium BC". In Klimscha, Florian (ed.). Wasserwirtschaftliche Innovationen im archäologischen Kontext. Von den prähistorischen Anfängen bis zu den Metropolen der Antike . Rahden/Westfalia: Leidorf. pp. 69– 82. ^ Galili, Ehud; Nir, Yaacov (1993). "The submerged Pre-Pottery Neolithic water well of Atlit-Yam, northern Israel, and its palaeoenvironmental implications". The Holocene . 3 (3): 265– 270. Bibcode : 1993Holoc...3..265G . doi : 10.1177/095968369300300309 . S2CID 130032420 . ^ Rybníček, Michal; Kočár, Petr; Muigg, Bernhard; Peška, Jaroslav; Sedláček, Radko; Tegel, Willy; Kolář, Tomáš (2020). "World's oldest dendrochronologically dated archaeological wood construction" . Journal of Archaeological Science . 115 105082. Bibcode : 2020JArSc.115j5082R . doi : 10.1016/j.jas.2020.105082 . S2CID 213707193 . ^ "Kückhovener Brunnen – Dorfgemeinschaft Kückhoven E. V." [ permanent dead link ] ^ Tegel W, Elburg R, Hakelberg D, Stäuble H, Büntgen U (2012). "Early Neolithic Water Wells Reveal the World's Oldest Wood Architecture" . PLOS ONE . 7 (12) e51374. Bibcode : 2012PLoSO...751374T . doi : 10.1371/journal.pone.0051374 . PMC 3526582 . PMID 23284685 . ^ a b Kuhn, Oliver (2004-06-30). "Ancient Chinese Drilling" . Canadian Society of Exploration Geophysicists . 29 (6). ^ a b Chang, Mingteh (2012). Forest Hydrology: An Introduction to Water and Forests (3rd ed.). CRC Press (published November 1, 2012). p. 31. ISBN 978-1-4398-7994-8 . ^ Koon, Wee Kek (July 25, 2015). "How the ancient Chinese looked after their drinking water" . South China Morning Post . ^ "Sakieh explication/difference vs Sakia" . Britannica.com . Retrieved 2011-12-19 . ^ "Sakia explication" . Britannica.com . Retrieved 2011-12-19 . ^ "Stone Age wells found in Cyprus" . BBC News . ^ Ashkenazi, Eli (November 9, 2012). "Ancient Well Reveals Secrets of First Jezreel Valley Farmers" . Haaretz . ^ "ASTM International – Standards Worldwide" . www.astm.org . Archived from the original on 2020-08-01 . Retrieved 2019-02-01 . ^ Joseph P. Riva Jr. and Gordon I. Atwater. "petroleum" . Encyclopædia Britannica . Retrieved 2008-06-30 . ^ "Woodingdean Well" . 2005 . Retrieved 26 Jan 2010 . ^ "St. Patrick's Well" . Umbriatravel.com . Retrieved 2011-12-19 . [ permanent dead link ] ^ "How I drill a Well." Popular Science , April 1952, pp. 177–181. ^ Association), NKBA (National Kitchen and Bath (2013-10-29). Kitchen & Bath Residential Construction and Systems . John Wiley & Sons. ISBN 978-1-118-71104-0 . ^ "Artesian Water and Artesian Wells \| U.S. Geological Survey" . www.usgs.gov . 2018-10-09 . Retrieved 2026-03-23 . ^ Arnold, L.R.; Flynn, J.L.; Paschke, S.S. (2009-10-20). "Design and installation of a groundwater monitoring-well network in the High Plains aquifer, Colorado" . USGS Report . Data Series. U.S. Geological Survey: 5. Bibcode : 2009usgs.rept....5A . doi : 10.3133/ds456 . Retrieved 27 May 2024 . ^ Du Preez, Michael. "ELECTRO-SEISMIC SURVEYS APPLIED TO MODDELING OF GROUNDWATER FLOW SYSTEMS" (PDF) . Bloemfontein, South Africa. Archived from the original (PDF) on 31 May 2011 . Retrieved 21 April 2011 . ^ a b c d e Committee on Environmental Health; Committee on Infectious Diseases (2009). "Drinking water from private wells and risks to children" . Pediatrics . 123 (6): 1599– 1605. doi : 10.1542/peds.2009-0751 . PMID 19482772 . ^ Wiebe, Andrew J.; Rudolph, David L.; Pasha, Ehsan; Brook, Jacqueline M.; Christie, Mike; Menkveld, Paul G. (2021). "Impacts of Event-Based Recharge on the Vulnerability of Public Supply Wells" . Sustainability . 13 (14): 7695. Bibcode : 2021Sust...13.7695W . doi : 10.3390/su13147695 . ISSN 2071-1050 . ^ Association, American Water Works (2003). Water Sources . American Water Works Association. ISBN 978-1-58321-229-5 . ^ Meulemans, C. C. E. (1987-09-01). "The Basic Principles of UV–Disinfection of Water". Ozone: Science & Engineering . 9 (4): 299– 313. Bibcode : 1987OzSE....9..299M . doi : 10.1080/01919518708552146 . ISSN 0191-9512 . ^ "Soil salination by placement of water wells mentioned in India" . Ngm.nationalgeographic.com. 2002-10-17. Archived from the original on May 22, 2009 . Retrieved 2011-12-19 . ^ "Practical Answers – Handpumps" . Practicalaction.org . Retrieved 2011-12-19 . ^ "Treadle pump" . Dev.practicalaction.org . Retrieved 2011-12-19 . ^ Famiglietti, James S.; Ferguson, Grant (23 April 2021). "The hidden crisis beneath our feet" . Science . 372 (6540): 344– 345. Bibcode : 2021Sci...372..344F . doi : 10.1126/science.abh2867 . PMID 33888627 . S2CID 233353241 . Retrieved 10 May 2021 . ^ "The largest assessment of global groundwater wells finds many are at risk of drying up" . ScienceDaily . Retrieved 10 May 2021 . ^ Jasechko, Scott; Perrone, Debra (23 April 2021). "Global groundwater wells at risk of running dry" . Science . 372 (6540): 418– 421. Bibcode : 2021Sci...372..418J . doi : 10.1126/science.abc2755 . ISSN 0036-8075 . PMID 33888642 . S2CID 233353207 . Retrieved 10 May 2021 . ^ Burr, Thomas Benge (1766). The History of Tunbridge Wells . London. Archived from the original on 2021-01-31 . Retrieved 2019-10-09 . ^ Russo, Lucio (2004). The Forgotten Revolution . Berlin: Springer. pp. 273– 277. ^ Bromiley, Geoffrey W. (1982), International Standard Bible Encyclopedia: E-J , Wm. B. Eerdmans Publishing, p. 955, ISBN 978-0-8028-3782-0 ^ "Well Flow Equations" (PDF) . Cal Poly Humboldt, Department of Geology . Retrieved June 13, 2022 . ^ "How Much Water Can the Well Deliver" . Inspectapedia . Retrieved June 13, 2022 . Driscoll, F. (1986). Groundwater and Wells . St. Paul : Johnson Filtration Systems. ISBN 978-0-9616456-0-1 . Raymond Rowles (1995). Drilling for Water (2nd ed.). Avebury, Cranfield University. ISBN 1-85628-984-2 . Sustainable Groundwater Development theme of the Rural Water Supply Network (RWSN) Water Portal – Akvopedia Archived 2014-10-18 at the Wayback Machine Sustainable Sanitation and Water Management Toolbox U.S. Centers for Disease Control and Prevention (CDC) Healthy Water – Water Wells Site covering well basics, guidelines for proper siting and location of wells to avoid contamination, well testing, diseases related to wells, emergency well treatment and other topics. US Geological Survey – Ground water: Wells US Geological Survey – Water Science Pictures Flowing Artesian Well Drilling wells 18 extremely useful questions and answers American Ground Water Trust Lifewater International Technical Library Archived 2013-06-16 at the Wayback Machine Well Construction Technical Resources for NGOs
Markdown	[Jump to content](https://en.wikipedia.org/wiki/Well#bodyContent) Main menu Main menu move to sidebar hide Navigation - [Main page](https://en.wikipedia.org/wiki/Main_Page "Visit the main page [z]") - [Contents](https://en.wikipedia.org/wiki/Wikipedia:Contents "Guides to browsing Wikipedia") - [Current events](https://en.wikipedia.org/wiki/Portal:Current_events "Articles related to current events") - [Random article](https://en.wikipedia.org/wiki/Special:Random "Visit a randomly selected article [x]") - [About Wikipedia](https://en.wikipedia.org/wiki/Wikipedia:About "Learn about Wikipedia and how it works") - [Contact us](https://en.wikipedia.org/wiki/Wikipedia:Contact_us "How to contact Wikipedia") Contribute - [Help](https://en.wikipedia.org/wiki/Help:Contents "Guidance on how to use and edit Wikipedia") - [Learn to edit](https://en.wikipedia.org/wiki/Help:Introduction "Learn how to edit Wikipedia") - [Community portal](https://en.wikipedia.org/wiki/Wikipedia:Community_portal "The hub for editors") - [Recent changes](https://en.wikipedia.org/wiki/Special:RecentChanges "A list of recent changes to Wikipedia [r]") - [Upload file](https://en.wikipedia.org/wiki/Wikipedia:File_upload_wizard "Add images or other media for use on Wikipedia") - [Special pages](https://en.wikipedia.org/wiki/Special:SpecialPages "A list of all special pages [q]") [![](https://en.wikipedia.org/static/images/icons/enwiki-25.svg) ![Wikipedia](https://en.wikipedia.org/static/images/mobile/copyright/wikipedia-wordmark-en-25.svg) ![The Free Encyclopedia](https://en.wikipedia.org/static/images/mobile/copyright/wikipedia-tagline-en-25.svg)](https://en.wikipedia.org/wiki/Main_Page) [Search](https://en.wikipedia.org/wiki/Special:Search "Search Wikipedia [f]") Appearance - [Donate](https://donate.wikimedia.org/?wmf_source=donate&wmf_medium=sidebar&wmf_campaign=en.wikipedia.org&uselang=en) - [Create account](https://en.wikipedia.org/w/index.php?title=Special:CreateAccount&returnto=Well "You are encouraged to create an account and log in; however, it is not mandatory") - [Log in](https://en.wikipedia.org/w/index.php?title=Special:UserLogin&returnto=Well "You're encouraged to log in; however, it's not mandatory. [o]") Personal tools - [Donate](https://donate.wikimedia.org/?wmf_source=donate&wmf_medium=sidebar&wmf_campaign=en.wikipedia.org&uselang=en) - [Create account](https://en.wikipedia.org/w/index.php?title=Special:CreateAccount&returnto=Well "You are encouraged to create an account and log in; however, it is not mandatory") - [Log in](https://en.wikipedia.org/w/index.php?title=Special:UserLogin&returnto=Well "You're encouraged to log in; however, it's not mandatory. [o]") ## Contents move to sidebar hide - [(Top)](https://en.wikipedia.org/wiki/Well) - [1 History](https://en.wikipedia.org/wiki/Well#History) - [2 Types](https://en.wikipedia.org/wiki/Well#Types) Toggle Types subsection - [2\.1 Dug wells](https://en.wikipedia.org/wiki/Well#Dug_wells) - [2\.2 Driven wells](https://en.wikipedia.org/wiki/Well#Driven_wells) - [2\.3 Drilled wells](https://en.wikipedia.org/wiki/Well#Drilled_wells) - [3 Classification](https://en.wikipedia.org/wiki/Well#Classification) - [4 Siting](https://en.wikipedia.org/wiki/Well#Siting) - [5 Contamination](https://en.wikipedia.org/wiki/Well#Contamination) Toggle Contamination subsection - [5\.1 Pathogens](https://en.wikipedia.org/wiki/Well#Pathogens) - [5\.2 Chemical contamination](https://en.wikipedia.org/wiki/Well#Chemical_contamination) - [5\.3 Prevention](https://en.wikipedia.org/wiki/Well#Prevention) - [5\.4 Mitigation](https://en.wikipedia.org/wiki/Well#Mitigation) - [6 Environmental problems](https://en.wikipedia.org/wiki/Well#Environmental_problems) Toggle Environmental problems subsection - [6\.1 Soil salination](https://en.wikipedia.org/wiki/Well#Soil_salination) - [6\.2 Methane](https://en.wikipedia.org/wiki/Well#Methane) - [6\.3 PFAS/PFOS Fire fighting foam](https://en.wikipedia.org/wiki/Well#PFAS/PFOS_Fire_fighting_foam) - [7 Water security](https://en.wikipedia.org/wiki/Well#Water_security) - [8 Society and culture](https://en.wikipedia.org/wiki/Well#Society_and_culture) - [9 A simple model for water well recovery](https://en.wikipedia.org/wiki/Well#A_simple_model_for_water_well_recovery) - [10 Similar and related water structures](https://en.wikipedia.org/wiki/Well#Similar_and_related_water_structures) - [11 See also](https://en.wikipedia.org/wiki/Well#See_also) - [12 References](https://en.wikipedia.org/wiki/Well#References) Toggle References subsection - [12\.1 Bibliography](https://en.wikipedia.org/wiki/Well#Bibliography) - [13 External links](https://en.wikipedia.org/wiki/Well#External_links) Toggle the table of contents # Well 123 languages - [Alemannisch](https://als.wikipedia.org/wiki/Brunnen "Brunnen – Alemannic") - [Aragonés](https://an.wikipedia.org/wiki/Pozo "Pozo – Aragonese") - [अंगिका](https://anp.wikipedia.org/wiki/%E0%A4%87%E0%A4%A8%E0%A4%BE%E0%A4%B0%E0%A4%BE "इनारा – Angika") - [العربية](https://ar.wikipedia.org/wiki/%D8%A8%D8%A6%D8%B1 "بئر – Arabic") - [অসমীয়া](https://as.wikipedia.org/wiki/%E0%A6%95%E0%A7%81%E0%A6%81%E2%80%8C%E0%A7%B1%E0%A6%BE "কুঁ‌ৱা – Assamese") - [Asturianu](https://ast.wikipedia.org/wiki/Pozu "Pozu – Asturian") - [Aymar aru](https://ay.wikipedia.org/wiki/Phuju "Phuju – Aymara") - [Azərbaycanca](https://az.wikipedia.org/wiki/Quyu "Quyu – Azerbaijani") - [Basa Bali](https://ban.wikipedia.org/wiki/S%C3%A9m%C3%A9r "Sémér – Balinese") - [Boarisch](https://bar.wikipedia.org/wiki/Brunn "Brunn – Bavarian") - [Žemaitėška](https://bat-smg.wikipedia.org/wiki/%C5%A0oln%C4%97s "Šolnės – Samogitian") - [Bikol Central](https://bcl.wikipedia.org/wiki/Bubon "Bubon – Central Bikol") - [Беларуская (тарашкевіца)](https://be-tarask.wikipedia.org/wiki/%D0%A1%D1%82%D1%83%D0%B4%D0%BD%D1%8F "Студня – Belarusian (Taraškievica orthography)") - [Беларуская](https://be.wikipedia.org/wiki/%D0%9A%D0%B0%D0%BB%D0%BE%D0%B4%D0%B7%D0%B5%D0%B6 "Калодзеж – Belarusian") - [Български](https://bg.wikipedia.org/wiki/%D0%92%D0%BE%D0%B4%D0%B5%D0%BD_%D0%BA%D0%BB%D0%B0%D0%B4%D0%B5%D0%BD%D0%B5%D1%86 "Воден кладенец – Bulgarian") - [भोजपुरी](https://bh.wikipedia.org/wiki/%E0%A4%87%E0%A4%A8%E0%A4%BE%E0%A4%B0 "इनार – Bhojpuri") - [বাংলা](https://bn.wikipedia.org/wiki/%E0%A6%95%E0%A7%82%E0%A6%AA "কূপ – Bangla") - [Brezhoneg](https://br.wikipedia.org/wiki/Pu%C3%B1s "Puñs – Breton") - [Bosanski](https://bs.wikipedia.org/wiki/Bunar "Bunar – Bosnian") - [Català](https://ca.wikipedia.org/wiki/Pou "Pou – Catalan") - [閩東語 / Mìng-dĕ̤ng-ngṳ̄](https://cdo.wikipedia.org/wiki/Ci%C4%81ng "Ciāng – Mindong") - [Tsetsêhestâhese](https://chy.wikipedia.org/wiki/V%C3%B3t%C3%A2h%C3%A1%C3%A9no "Vótâháéno – Cheyenne") - [Čeština](https://cs.wikipedia.org/wiki/Studna "Studna – Czech") - [Чӑвашла](https://cv.wikipedia.org/wiki/%C3%87%C4%83%D0%BB "Çăл – Chuvash") - [Dansk](https://da.wikipedia.org/wiki/Br%C3%B8nd "Brønd – Danish") - [Deutsch](https://de.wikipedia.org/wiki/Brunnen "Brunnen – German") - [Zazaki](https://diq.wikipedia.org/wiki/Bir_\(co%C4%9Frafya\) "Bir (coğrafya) – Dimli") - [Ελληνικά](https://el.wikipedia.org/wiki/%CE%A0%CE%B7%CE%B3%CE%AC%CE%B4%CE%B9 "Πηγάδι – Greek") - [Esperanto](https://eo.wikipedia.org/wiki/Puto "Puto – Esperanto") - [Español](https://es.wikipedia.org/wiki/Pozo "Pozo – Spanish") - [Eesti](https://et.wikipedia.org/wiki/Kaev "Kaev – Estonian") - [Euskara](https://eu.wikipedia.org/wiki/Putzu "Putzu – Basque") - [فارسی](https://fa.wikipedia.org/wiki/%DA%86%D8%A7%D9%87_%D8%A2%D8%A8 "چاه آب – Persian") - [Suomi](https://fi.wikipedia.org/wiki/Kaivo "Kaivo – Finnish") - [Français](https://fr.wikipedia.org/wiki/Puits_%C3%A0_eau "Puits à eau – French") - [Nordfriisk](https://frr.wikipedia.org/wiki/Suas "Suas – Northern Frisian") - [Gaeilge](https://ga.wikipedia.org/wiki/Tobar "Tobar – Irish") - [Galego](https://gl.wikipedia.org/wiki/Pozo "Pozo – Galician") - [Avañe'ẽ](https://gn.wikipedia.org/wiki/Ykua "Ykua – Guarani") - [ગુજરાતી](https://gu.wikipedia.org/wiki/%E0%AA%95%E0%AB%82%E0%AA%B5%E0%AB%8B "કૂવો – Gujarati") - [Gungbe](https://guw.wikipedia.org/wiki/Dot%E1%BB%8D "Dotọ – Gun") - [Hausa](https://ha.wikipedia.org/wiki/Rijiya_Mai_Zurfi "Rijiya Mai Zurfi – Hausa") - [עברית](https://he.wikipedia.org/wiki/%D7%91%D7%90%D7%A8_%D7%9E%D7%99%D7%9D "באר מים – Hebrew") - [हिन्दी](https://hi.wikipedia.org/wiki/%E0%A4%95%E0%A5%81%E0%A4%86%E0%A4%81 "कुआँ – Hindi") - [Hrvatski](https://hr.wikipedia.org/wiki/Zdenac "Zdenac – Croatian") - [Kreyòl ayisyen](https://ht.wikipedia.org/wiki/Pwi "Pwi – Haitian Creole") - [Magyar](https://hu.wikipedia.org/wiki/K%C3%BAt "Kút – Hungarian") - [Հայերեն](https://hy.wikipedia.org/wiki/%D5%8B%D6%80%D5%B0%D5%B8%D6%80_\(%D5%BB%D6%80%D5%A1%D5%BF%D5%A5%D5%AD%D5%B6%D5%AB%D5%AF%D5%A1%D5%AF%D5%A1%D5%B6_%D5%AF%D5%A1%D5%BC%D5%B8%D6%82%D5%B5%D6%81\) "Ջրհոր (ջրատեխնիկական կառույց) – Armenian") - [Արեւմտահայերէն](https://hyw.wikipedia.org/wiki/%D5%8B%D6%80%D5%B0%D5%B8%D6%80 "Ջրհոր – Western Armenian") - [Interlingua](https://ia.wikipedia.org/wiki/Puteo "Puteo – Interlingua") - [Bahasa Indonesia](https://id.wikipedia.org/wiki/Sumur "Sumur – Indonesian") - [Iñupiatun](https://ik.wikipedia.org/wiki/Nivviaq "Nivviaq – Inupiaq") - [Italiano](https://it.wikipedia.org/wiki/Pozzo "Pozzo – Italian") - [日本語](https://ja.wikipedia.org/wiki/%E4%BA%95%E6%88%B8 "井戸 – Japanese") - [Jawa](https://jv.wikipedia.org/wiki/Sumur "Sumur – Javanese") - [Қазақша](https://kk.wikipedia.org/wiki/%D2%9A%D2%B1%D0%B4%D1%8B%D2%9B "Құдық – Kazakh") - [ಕನ್ನಡ](https://kn.wikipedia.org/wiki/%E0%B2%AC%E0%B2%BE%E0%B2%B5%E0%B2%BF "ಬಾವಿ – Kannada") - [한국어](https://ko.wikipedia.org/wiki/%EC%9A%B0%EB%AC%BC "우물 – Korean") - [کٲشُر](https://ks.wikipedia.org/wiki/%DA%A9%D8%B1%D9%9B%DB%8C%D9%88%D9%97%D9%84 "کرٛیوٗل – Kashmiri") - [Kurdî](https://ku.wikipedia.org/wiki/%C3%87al "Çal – Kurdish") - [Коми](https://kv.wikipedia.org/wiki/%D3%A6%D1%88%D0%BC%D3%A7%D1%81 "Ӧшмӧс – Komi") - [Latina](https://la.wikipedia.org/wiki/Puteus "Puteus – Latin") - [Lëtzebuergesch](https://lb.wikipedia.org/wiki/P%C3%ABtz "Pëtz – Luxembourgish") - [Limburgs](https://li.wikipedia.org/wiki/Waterp%C3%B6t "Waterpöt – Limburgish") - [Lombard](https://lmo.wikipedia.org/wiki/Pozz "Pozz – Lombard") - [Lietuvių](https://lt.wikipedia.org/wiki/%C5%A0ulinys "Šulinys – Lithuanian") - [Latviešu](https://lv.wikipedia.org/wiki/Aka "Aka – Latvian") - [Minangkabau](https://min.wikipedia.org/wiki/Sumua "Sumua – Minangkabau") - [Македонски](https://mk.wikipedia.org/wiki/%D0%91%D1%83%D0%BD%D0%B0%D1%80 "Бунар – Macedonian") - [മലയാളം](https://ml.wikipedia.org/wiki/%E0%B4%95%E0%B4%BF%E0%B4%A3%E0%B5%BC "കിണർ – Malayalam") - [मराठी](https://mr.wikipedia.org/wiki/%E0%A4%B5%E0%A4%BF%E0%A4%B9%E0%A5%80%E0%A4%B0 "विहीर – Marathi") - [Bahasa Melayu](https://ms.wikipedia.org/wiki/Perigi "Perigi – Malay") - [မြန်မာဘာသာ](https://my.wikipedia.org/wiki/%E1%80%A1%E1%80%9D%E1%80%AE%E1%80%85%E1%80%AD%E1%80%90%E1%80%BD%E1%80%84%E1%80%BA%E1%80%B8 "အဝီစိတွင်း – Burmese") - [Napulitano](https://nap.wikipedia.org/wiki/Puzzo "Puzzo – Neapolitan") - [Plattdüütsch](https://nds.wikipedia.org/wiki/Sood "Sood – Low German") - [नेपाली](https://ne.wikipedia.org/wiki/%E0%A4%AA%E0%A4%A7%E0%A5%87%E0%A4%81%E0%A4%B0%E0%A4%BE "पधेँरा – Nepali") - [Li Niha](https://nia.wikipedia.org/wiki/Hele "Hele – Nias") - [Nederlands](https://nl.wikipedia.org/wiki/Waterput "Waterput – Dutch") - [Norsk nynorsk](https://nn.wikipedia.org/wiki/Brunn "Brunn – Norwegian Nynorsk") - [Norsk bokmål](https://no.wikipedia.org/wiki/Br%C3%B8nn "Brønn – Norwegian Bokmål") - [Nouormand](https://nrm.wikipedia.org/wiki/Pyit "Pyit – Norman") - [Occitan](https://oc.wikipedia.org/wiki/Potz "Potz – Occitan") - [Ирон](https://os.wikipedia.org/wiki/%D0%A6%D1%8A%D0%B0%D0%B9 "Цъай – Ossetic") - [ਪੰਜਾਬੀ](https://pa.wikipedia.org/wiki/%E0%A8%96%E0%A9%82%E0%A8%B9 "ਖੂਹ – Punjabi") - [Picard](https://pcd.wikipedia.org/wiki/Pure_\(treu\) "Pure (treu) – Picard") - [Deitsch](https://pdc.wikipedia.org/wiki/Brunne "Brunne – Pennsylvania German") - [Polski](https://pl.wikipedia.org/wiki/Studnia "Studnia – Polish") - [Piemontèis](https://pms.wikipedia.org/wiki/Poss_d%27eva "Poss d'eva – Piedmontese") - [پنجابی](https://pnb.wikipedia.org/wiki/%DA%A9%DA%BE%D9%88%DB%81 "کھوہ – Western Punjabi") - [پښتو](https://ps.wikipedia.org/wiki/%D8%AF_%D8%A7%D8%A8%D9%88_%DA%85%D8%A7%DA%AB%D8%A7%D9%86%DB%90 "د ابو څاګانې – Pashto") - [Português](https://pt.wikipedia.org/wiki/Po%C3%A7o "Poço – Portuguese") - [Runa Simi](https://qu.wikipedia.org/wiki/Yaku_hurquna "Yaku hurquna – Quechua") - [Română](https://ro.wikipedia.org/wiki/Pu%C8%9B_de_ap%C4%83 "Puț de apă – Romanian") - [Руски](https://rsk.wikipedia.org/wiki/%D0%A1%D1%82%D1%83%D0%B4%D0%BD%D1%8F "Студня – Pannonian Rusyn") - [Русский](https://ru.wikipedia.org/wiki/%D0%9A%D0%BE%D0%BB%D0%BE%D0%B4%D0%B5%D1%86 "Колодец – Russian") - [Sicilianu](https://scn.wikipedia.org/wiki/Puzzu "Puzzu – Sicilian") - [Srpskohrvatski / српскохрватски](https://sh.wikipedia.org/wiki/Bunar "Bunar – Serbo-Croatian") - [Simple English](https://simple.wikipedia.org/wiki/Well "Well – Simple English") - [Slovenčina](https://sk.wikipedia.org/wiki/Stud%C5%88a "Studňa – Slovak") - [Slovenščina](https://sl.wikipedia.org/wiki/Vodnjak "Vodnjak – Slovenian") - [ChiShona](https://sn.wikipedia.org/wiki/Tsime "Tsime – Shona") - [Soomaaliga](https://so.wikipedia.org/wiki/Ceel "Ceel – Somali") - [Shqip](https://sq.wikipedia.org/wiki/Pusi "Pusi – Albanian") - [Српски / srpski](https://sr.wikipedia.org/wiki/%D0%91%D1%83%D0%BD%D0%B0%D1%80 "Бунар – Serbian") - [Sesotho](https://st.wikipedia.org/wiki/Sediba "Sediba – Southern Sotho") - [Sunda](https://su.wikipedia.org/wiki/Sumur "Sumur – Sundanese") - [Svenska](https://sv.wikipedia.org/wiki/Brunn "Brunn – Swedish") - [Sakizaya](https://szy.wikipedia.org/wiki/tebun "tebun – Sakizaya") - [தமிழ்](https://ta.wikipedia.org/wiki/%E0%AE%95%E0%AE%BF%E0%AE%A3%E0%AE%B1%E0%AF%81 "கிணறு – Tamil") - [తెలుగు](https://te.wikipedia.org/wiki/%E0%B0%AC%E0%B0%BE%E0%B0%B5%E0%B0%BF "బావి – Telugu") - [Tagalog](https://tl.wikipedia.org/wiki/Balon "Balon – Tagalog") - [Tolışi](https://tly.wikipedia.org/wiki/Col "Col – Talysh") - [Türkçe](https://tr.wikipedia.org/wiki/Kuyu "Kuyu – Turkish") - [Українська](https://uk.wikipedia.org/wiki/%D0%9A%D1%80%D0%B8%D0%BD%D0%B8%D1%86%D1%8F "Криниця – Ukrainian") - [اردو](https://ur.wikipedia.org/wiki/%DA%A9%D9%86%D9%88%D8%A7%DA%BA "کنواں – Urdu") - [Oʻzbekcha / ўзбекча](https://uz.wikipedia.org/wiki/Quduq "Quduq – Uzbek") - [Vepsän kel’](https://vep.wikipedia.org/wiki/Kaiv "Kaiv – Veps") - [Tiếng Việt](https://vi.wikipedia.org/wiki/Gi%E1%BA%BFng "Giếng – Vietnamese") - [Walon](https://wa.wikipedia.org/wiki/Pousse "Pousse – Walloon") - [吴语](https://wuu.wikipedia.org/wiki/%E4%BA%95 "井 – Wu") - [閩南語 / Bân-lâm-gí](https://zh-min-nan.wikipedia.org/wiki/Ch%C3%A9%E2%81%BF "Chéⁿ – Minnan") - [粵語](https://zh-yue.wikipedia.org/wiki/%E4%BA%95 "井 – Cantonese") - [中文](https://zh.wikipedia.org/wiki/%E4%BA%95 "井 – Chinese") [Edit links](https://www.wikidata.org/wiki/Special:EntityPage/Q43483#sitelinks-wikipedia "Edit interlanguage links") - [Article](https://en.wikipedia.org/wiki/Well "View the content page [c]") - [Talk](https://en.wikipedia.org/wiki/Talk:Well "Discuss improvements to the content page [t]") English - [Read](https://en.wikipedia.org/wiki/Well) - [Edit](https://en.wikipedia.org/w/index.php?title=Well&action=edit "Edit this page [e]") - [View history](https://en.wikipedia.org/w/index.php?title=Well&action=history "Past revisions of this page [h]") Tools Tools move to sidebar hide Actions - [Read](https://en.wikipedia.org/wiki/Well) - [Edit](https://en.wikipedia.org/w/index.php?title=Well&action=edit "Edit this page [e]") - [View history](https://en.wikipedia.org/w/index.php?title=Well&action=history) General - [What links here](https://en.wikipedia.org/wiki/Special:WhatLinksHere/Well "List of all English Wikipedia pages containing links to this page [j]") - [Related changes](https://en.wikipedia.org/wiki/Special:RecentChangesLinked/Well "Recent changes in pages linked from this page [k]") - [Upload file](https://en.wikipedia.org/wiki/Wikipedia:File_Upload_Wizard "Upload files [u]") - [Permanent link](https://en.wikipedia.org/w/index.php?title=Well&oldid=1348155091 "Permanent link to this revision of this page") - [Page information](https://en.wikipedia.org/w/index.php?title=Well&action=info "More information about this page") - [Cite this page](https://en.wikipedia.org/w/index.php?title=Special:CiteThisPage&page=Well&id=1348155091&wpFormIdentifier=titleform "Information on how to cite this page") - [Get shortened URL](https://en.wikipedia.org/w/index.php?title=Special:UrlShortener&url=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FWell) Print/export - [Download as PDF](https://en.wikipedia.org/w/index.php?title=Special:DownloadAsPdf&page=Well&action=show-download-screen "Download this page as a PDF file") - [Printable version](https://en.wikipedia.org/w/index.php?title=Well&printable=yes "Printable version of this page [p]") In other projects - [Wikimedia Commons](https://commons.wikimedia.org/wiki/Category:Water_wells) - [Wikidata item](https://www.wikidata.org/wiki/Special:EntityPage/Q43483 "Structured data on this page hosted by Wikidata [g]") Appearance move to sidebar hide From Wikipedia, the free encyclopedia Excavation or structure to provide access to groundwater This article is about water wells. For other uses, see [Well (disambiguation)](https://en.wikipedia.org/wiki/Well_\(disambiguation\) "Well (disambiguation)"). "Village pump" redirects here. For the set of Wikipedia discussion pages, see [Wikipedia:Village pump](https://en.wikipedia.org/wiki/Wikipedia:Village_pump "Wikipedia:Village pump"). [![](https://upload.wikimedia.org/wikipedia/commons/thumb/0/01/Faryab-_village_dug_well.JPG/250px-Faryab-_village_dug_well.JPG)](https://en.wikipedia.org/wiki/File:Faryab-_village_dug_well.JPG) A dug well in a village in [Faryab Province](https://en.wikipedia.org/wiki/Faryab_Province "Faryab Province"), [Afghanistan](https://en.wikipedia.org/wiki/Afghanistan "Afghanistan") [![](https://upload.wikimedia.org/wikipedia/commons/thumb/0/02/Well-cistern.jpg/250px-Well-cistern.jpg)](https://en.wikipedia.org/wiki/File:Well-cistern.jpg) The difference between a well and a [cistern](https://en.wikipedia.org/wiki/Cistern "Cistern") is in the source of the water: a cistern collects [rainwater](https://en.wikipedia.org/wiki/Rainwater "Rainwater") whereas a well draws from [groundwater](https://en.wikipedia.org/wiki/Groundwater "Groundwater"). A well is an excavation or structure created on the earth by [digging](https://en.wikipedia.org/wiki/Digging "Digging"), driving, or [drilling](https://en.wikipedia.org/wiki/Drilling "Drilling") to access [liquid](https://en.wikipedia.org/wiki/Liquid "Liquid") resources, usually [water](https://en.wikipedia.org/wiki/Water "Water"). The oldest and most common kind of well is a water well, to access [groundwater](https://en.wikipedia.org/wiki/Groundwater "Groundwater") in underground [aquifers](https://en.wikipedia.org/wiki/Aquifer "Aquifer"). The well water is drawn up by a [pump](https://en.wikipedia.org/wiki/Pump "Pump"), or using containers, such as [buckets](https://en.wikipedia.org/wiki/Bucket "Bucket") that are raised mechanically or by hand. Water can also be [injected back into the aquifer](https://en.wikipedia.org/wiki/Aquifer_storage_and_recovery "Aquifer storage and recovery") through the well. Wells were first constructed at least eight thousand years ago and historically vary in construction from a sediment of a dry watercourse to the [qanats](https://en.wikipedia.org/wiki/Qanat "Qanat") of Iran, and the [stepwells](https://en.wikipedia.org/wiki/Stepwell "Stepwell") and [sakiehs](https://en.wikipedia.org/wiki/Sakia "Sakia") of India. Placing a lining in the well shaft helps create stability, and linings of wood or [wickerwork](https://en.wikipedia.org/wiki/Wicker "Wicker") date back at least as far as the [Iron Age](https://en.wikipedia.org/wiki/Iron_Age "Iron Age"). Wells have traditionally been sunk by hand digging, as is still the case in rural areas of the developing world. These wells are inexpensive and low-tech as they use mostly manual labour, and the structure can be lined with [brick](https://en.wikipedia.org/wiki/Brick "Brick") or stone as the excavation proceeds. A more modern method called [caissoning](https://en.wikipedia.org/wiki/Caisson_\(engineering\) "Caisson (engineering)") uses pre-cast reinforced concrete well rings that are lowered into the hole. Driven wells can be created in unconsolidated material with a well hole structure, which consists of a hardened drive point and a screen of perforated pipe, after which a pump is installed to collect the water. Deeper wells can be excavated by hand drilling methods or machine drilling, using a [bit](https://en.wikipedia.org/wiki/Drill_bit "Drill bit") in a [borehole](https://en.wikipedia.org/wiki/Borehole "Borehole"). Drilled wells are usually cased with a factory-made pipe composed of steel or plastic. Drilled wells can access water at much greater depths than dug wells. Two broad classes of well are shallow or unconfined wells completed within the uppermost saturated [aquifer](https://en.wikipedia.org/wiki/Aquifer "Aquifer") at that location, and deep or confined wells, sunk through an impermeable stratum into an aquifer beneath. A collector well can be constructed adjacent to a freshwater lake or stream with water percolating through the intervening material. The site of a well can be selected by a [hydrogeologist](https://en.wikipedia.org/wiki/Hydrogeology "Hydrogeology"), or groundwater surveyor. Water may be pumped or hand drawn. Impurities from the surface can easily reach shallow sources and contamination of the supply by pathogens or chemical contaminants needs to be avoided. Well water typically contains more minerals in solution than surface water and may require [treatment](https://en.wikipedia.org/wiki/Water_treatment "Water treatment") before being potable. [Soil salination](https://en.wikipedia.org/wiki/Soil_salinity "Soil salinity") can occur as the water table falls and the surrounding soil begins to dry out. Another environmental problem is the potential for [methane](https://en.wikipedia.org/wiki/Methane "Methane") to seep into the water. ## History \[[edit](https://en.wikipedia.org/w/index.php?title=Well&action=edit&section=1 "Edit section: History")\] See also: [History of water supply and sanitation](https://en.wikipedia.org/wiki/History_of_water_supply_and_sanitation "History of water supply and sanitation") [![](https://upload.wikimedia.org/wikipedia/commons/thumb/7/7b/Tunis1960-150_hg.jpg/250px-Tunis1960-150_hg.jpg)](https://en.wikipedia.org/wiki/File:Tunis1960-150_hg.jpg) Camel drawing water from a well, [Djerba](https://en.wikipedia.org/wiki/Djerba "Djerba") island, Tunisia, 1960 Very early [Neolithic](https://en.wikipedia.org/wiki/Neolithic "Neolithic") wells are known from the [Eastern Mediterranean](https://en.wikipedia.org/wiki/Eastern_Mediterranean "Eastern Mediterranean").[\[1\]](https://en.wikipedia.org/wiki/Well#cite_note-1) The oldest reliably dated well is from the [pre-pottery neolithic](https://en.wikipedia.org/wiki/Prehistoric_Cyprus#Aceramic_Neolithic "Prehistoric Cyprus") (PPN) site of Kissonerga-Mylouthkia on [Cyprus](https://en.wikipedia.org/wiki/Cyprus "Cyprus"). At around 8400 BC a shaft (well 116) of circular diameter was driven through limestone to reach an [aquifer](https://en.wikipedia.org/wiki/Aquifer "Aquifer") at a depth of 8 metres (26 ft). Well 2070 from Kissonerga-Mylouthkia, dating to the late PPN, reaches a depth of 13 metres (43 ft). Other slightly younger wells are known from this site and from neighbouring Parekklisha-Shillourokambos. A first stone lined[\[2\]](https://en.wikipedia.org/wiki/Well#cite_note-2) well of 5.5 metres (18 ft) depth is documented from a drowned final PPN (c. 7000 BC) site at ['Atlit-Yam](https://en.wikipedia.org/wiki/Atlit_Yam "Atlit Yam") off the coast near modern [Haifa](https://en.wikipedia.org/wiki/Haifa "Haifa") in [Israel](https://en.wikipedia.org/wiki/Israel "Israel"). [![](https://upload.wikimedia.org/wikipedia/commons/thumb/7/74/K%C3%BCckhoven_%28Erkelenz%29%2C_Brunnenbaureste_um_5300_v._Ch._.jpg/120px-K%C3%BCckhoven_%28Erkelenz%29%2C_Brunnenbaureste_um_5300_v._Ch._.jpg)](https://en.wikipedia.org/wiki/File:K%C3%BCckhoven_\(Erkelenz\),_Brunnenbaureste_um_5300_v._Ch._.jpg) Neolithic [Linear Pottery culture](https://en.wikipedia.org/wiki/Linear_Pottery_culture "Linear Pottery culture") well, 5300 BC, [Erkelenz](https://en.wikipedia.org/wiki/Erkelenz "Erkelenz"), Germany Wood-lined wells are known from the early Neolithic [Linear Pottery culture](https://en.wikipedia.org/wiki/Linear_Pottery_culture "Linear Pottery culture"), for example in Ostrov, Czech Republic, dated 5265 BC,[\[3\]](https://en.wikipedia.org/wiki/Well#cite_note-3) Kückhoven (an outlying centre of [Erkelenz](https://en.wikipedia.org/wiki/Erkelenz "Erkelenz")), dated 5300 BC,[\[4\]](https://en.wikipedia.org/wiki/Well#cite_note-4) and [Eythra](https://en.wikipedia.org/wiki/Eythra "Eythra") in Schletz (an outlying centre of [Asparn an der Zaya](https://en.wikipedia.org/wiki/Asparn_an_der_Zaya "Asparn an der Zaya")) in [Austria](https://en.wikipedia.org/wiki/Austria "Austria"), dated 5200 BC.[\[5\]](https://en.wikipedia.org/wiki/Well#cite_note-5) The Neolithic Chinese discovered and made extensive use of deep drilled groundwater for drinking.\[[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed "Wikipedia:Citation needed")\] The Chinese text [The Book of Changes](https://en.wikipedia.org/wiki/I_Ching "I Ching"), originally a divination text of the Western Zhou dynasty (1046 -771 BC), contains an entry describing how the ancient Chinese maintained their wells and protected their sources of water.[\[6\]](https://en.wikipedia.org/wiki/Well#cite_note-Kuhn2004-6) A well excavated at the [Hemedu](https://en.wikipedia.org/wiki/Hemudu_culture "Hemudu culture") excavation site was believed to have been built during the neolithic era.[\[7\]](https://en.wikipedia.org/wiki/Well#cite_note-Chang2012-7) The well was cased by four rows of logs with a square frame attached to them at the top of the well. 60 additional tile wells southwest of Beijing are also believed to have been built around 600 BC for drinking and irrigation.[\[7\]](https://en.wikipedia.org/wiki/Well#cite_note-Chang2012-7)[\[8\]](https://en.wikipedia.org/wiki/Well#cite_note-8) [![](https://upload.wikimedia.org/wikipedia/commons/thumb/7/73/Model_well%2C_burial_find%2C_China%2C_Han_dynasty%2C_206_BC_to_220_AD%2C_earthenware_-_%C3%96stasiatiska_museet%2C_Stockholm_-_DSC09578.JPG/250px-Model_well%2C_burial_find%2C_China%2C_Han_dynasty%2C_206_BC_to_220_AD%2C_earthenware_-_%C3%96stasiatiska_museet%2C_Stockholm_-_DSC09578.JPG)](https://en.wikipedia.org/wiki/File:Model_well,_burial_find,_China,_Han_dynasty,_206_BC_to_220_AD,_earthenware_-_%C3%96stasiatiska_museet,_Stockholm_-_DSC09578.JPG) A Chinese ceramic model of a well with a water [pulley](https://en.wikipedia.org/wiki/Pulley "Pulley") system, excavated from a tomb of the [Han dynasty](https://en.wikipedia.org/wiki/Han_dynasty "Han dynasty") (202 BC – 220 AD) period In [Egypt](https://en.wikipedia.org/wiki/Egypt "Egypt"), [shadoofs](https://en.wikipedia.org/wiki/Shadoof "Shadoof") and [sakias](https://en.wikipedia.org/wiki/Sakia "Sakia") are used.[\[9\]](https://en.wikipedia.org/wiki/Well#cite_note-9)[\[10\]](https://en.wikipedia.org/wiki/Well#cite_note-10) The sakia is much more efficient, as it can bring up water from a depth of 10 metres (versus the 3 metres of the shadoof). The sakia is the Egyptian version of the [noria](https://en.wikipedia.org/wiki/Noria "Noria"). Some of the world's oldest known wells, located in Cyprus, date to 7000–8,500 BC.[\[11\]](https://en.wikipedia.org/wiki/Well#cite_note-11) Two wells from the Neolithic period, around 6500 BC, have been discovered in Israel. One is in Atlit, on the northern coast of Israel, and the other is in the Jezreel Valley.[\[12\]](https://en.wikipedia.org/wiki/Well#cite_note-12) Wells for other purposes came along much later, historically. The first recorded [salt well](https://en.wikipedia.org/wiki/Salt_well "Salt well") was dug in the Sichuan province of China around 2,250 years ago. This was the first time that ancient water well technology was applied successfully for the exploitation of salt, and marked the beginning of Sichuan's salt drilling industry.[\[6\]](https://en.wikipedia.org/wiki/Well#cite_note-Kuhn2004-6) The earliest known [oil wells](https://en.wikipedia.org/wiki/Oil_well "Oil well") were also drilled in China, in 347 CE. These wells had depths of up to about 240 metres (790 ft) and were drilled using [bits](https://en.wikipedia.org/wiki/Drill_bit "Drill bit") attached to [bamboo](https://en.wikipedia.org/wiki/Bamboo "Bamboo") poles.[\[13\]](https://en.wikipedia.org/wiki/Well#cite_note-ASTM-13) The oil was burned to evaporate [brine](https://en.wikipedia.org/wiki/Brine "Brine") and produce [salt](https://en.wikipedia.org/wiki/Sodium_chloride "Sodium chloride"). By the 10th century, extensive [bamboo](https://en.wikipedia.org/wiki/Bamboo "Bamboo") pipelines connected oil wells with salt springs. The ancient records of China and [Japan](https://en.wikipedia.org/wiki/Japan "Japan") are said to contain many allusions to the use of natural gas for lighting and heating. Petroleum was known as Burning water in Japan in the 7th century.[\[14\]](https://en.wikipedia.org/wiki/Well#cite_note-EB1911-14) ## Types \[[edit](https://en.wikipedia.org/w/index.php?title=Well&action=edit&section=2 "Edit section: Types")\] [![](https://upload.wikimedia.org/wikipedia/commons/thumb/7/77/Uwaynat_bin_Hussain_water_well_near_Simaisma.jpg/250px-Uwaynat_bin_Hussain_water_well_near_Simaisma.jpg)](https://en.wikipedia.org/wiki/File:Uwaynat_bin_Hussain_water_well_near_Simaisma.jpg) Water well near [Simaisma](https://en.wikipedia.org/wiki/Simaisma "Simaisma"), eastern Qatar [![](https://upload.wikimedia.org/wikipedia/commons/thumb/b/b8/Leather_bucket_of_a_well.jpg/250px-Leather_bucket_of_a_well.jpg)](https://en.wikipedia.org/wiki/File:Leather_bucket_of_a_well.jpg) Leather bucket used for the water well [![](https://upload.wikimedia.org/wikipedia/commons/thumb/a/a6/Well%2C_Historical_Village_%2C_Bhaini_Sahib%2C_Ludhyana_%2C_Punjab_%2C_India.JPG/250px-Well%2C_Historical_Village_%2C_Bhaini_Sahib%2C_Ludhyana_%2C_Punjab_%2C_India.JPG)](https://en.wikipedia.org/wiki/File:Well,_Historical_Village_,_Bhaini_Sahib,_Ludhyana_,_Punjab_,_India.JPG) Well, Historical Village, Bhaini Sahib, [Ludhiana](https://en.wikipedia.org/wiki/Ludhiana "Ludhiana"), [Punjab](https://en.wikipedia.org/wiki/Punjab,_India "Punjab, India"), India ### Dug wells \[[edit](https://en.wikipedia.org/w/index.php?title=Well&action=edit&section=3 "Edit section: Dug wells")\] [![](https://upload.wikimedia.org/wikipedia/commons/thumb/d/d6/Well.handdug.cased.mali.jpg/250px-Well.handdug.cased.mali.jpg)](https://en.wikipedia.org/wiki/File:Well.handdug.cased.mali.jpg) View into a hand-dug well cased with concrete rings. [Ouelessebougou](https://en.wikipedia.org/wiki/Ouelessebougou "Ouelessebougou"), Mali. [![](https://upload.wikimedia.org/wikipedia/commons/thumb/c/ca/Well_In_Kerala.JPG/250px-Well_In_Kerala.JPG)](https://en.wikipedia.org/wiki/File:Well_In_Kerala.JPG) A dug well in a village in [Kerala](https://en.wikipedia.org/wiki/Kerala "Kerala"), India [![](https://upload.wikimedia.org/wikipedia/commons/thumb/5/57/Open_Well_-_flower_bag_shaped_wall_and_podium_01.jpg/250px-Open_Well_-_flower_bag_shaped_wall_and_podium_01.jpg)](https://en.wikipedia.org/wiki/File:Open_Well_-_flower_bag_shaped_wall_and_podium_01.jpg) Well with a flower bag-shaped wall and podium Until recent centuries, all artificial wells were [pumpless](https://en.wikipedia.org/wiki/Pump "Pump") hand-dug wells of varying degrees of sophistication, and they remain a very important source of [potable water](https://en.wikipedia.org/wiki/Potable_water "Potable water") in some rural developing areas, where they are routinely dug and used today. Their indispensability has produced a number of literary references, literal and figurative, including the reference to the incident of [Jesus](https://en.wikipedia.org/wiki/Jesus "Jesus") meeting a woman at [Jacob](https://en.wikipedia.org/wiki/Jacob "Jacob")'s well ([John](https://en.wikipedia.org/wiki/Gospel_of_John "Gospel of John") 4:6) in the Bible and the "[Ding Dong Bell](https://en.wikipedia.org/wiki/Ding_Dong_Bell "Ding Dong Bell")" [nursery rhyme](https://en.wikipedia.org/wiki/Nursery_rhyme "Nursery rhyme") about a cat in a well. Hand-dug wells are excavations with diameters large enough to accommodate one or more people with shovels digging down to below the [water table](https://en.wikipedia.org/wiki/Water_table "Water table"). The excavation is braced horizontally to avoid landslide or erosion endangering the people digging. They can be lined with stone or brick; extending this lining upwards above the ground surface to form a wall around the well serves to reduce both contamination and accidental falls into the well. A more modern method called [caissoning](https://en.wikipedia.org/wiki/Caisson_\(engineering\) "Caisson (engineering)") uses reinforced concrete or plain concrete pre-cast well rings that are lowered into the hole. A well-digging team digs under a cutting ring and the well column slowly sinks into the [aquifer](https://en.wikipedia.org/wiki/Aquifer "Aquifer"), whilst protecting the team from collapse of the well [bore](https://en.wikipedia.org/wiki/Borehole "Borehole"). Hand-dug wells are inexpensive and low tech (compared to drilling) and they use mostly manual labour to access groundwater in rural locations of developing countries. They may be built with a high degree of community participation, or by local entrepreneurs who specialize in hand-dug wells. They have been successfully excavated to 60 metres (200 ft). They have low operational and maintenance costs, in part because water can be extracted by hand, without a pump. The water often comes from an aquifer or groundwater, and can be easily deepened, which may be necessary if the ground water level drops, by telescoping the lining further down into the aquifer. The yield of existing hand dug wells may be improved by deepening or introducing vertical tunnels or perforated pipes. Drawbacks to hand-dug wells are numerous. It can be impractical to hand dig wells in areas where hard rock is present, and they can be time-consuming to dig and line even in favourable areas. Because they exploit shallow aquifers, the well may be susceptible to yield fluctuations and possible contamination from surface water, including sewage. Hand dug well construction generally requires the use of a well trained construction team, and the capital investment for equipment such as concrete ring moulds, heavy lifting equipment, well shaft formwork, motorized de-watering pumps, and fuel can be large for people in developing countries. Construction of hand dug wells can be dangerous due to collapse of the well bore, falling objects and asphyxiation, including from dewatering pump exhaust fumes. The [Woodingdean Water Well](https://en.wikipedia.org/wiki/Woodingdean_Water_Well "Woodingdean Water Well"), hand-dug between 1858 and 1862, is the deepest hand-dug well at 392 metres (1,285 ft).[\[15\]](https://en.wikipedia.org/wiki/Well#cite_note-15) The [Big Well](https://en.wikipedia.org/wiki/Big_Well "Big Well") in [Greensburg, Kansas](https://en.wikipedia.org/wiki/Greensburg,_Kansas "Greensburg, Kansas"), is billed as the world's largest hand-dug well, at 109 feet (33 m) deep and 32 feet (9.8 m) in diameter. However, the Well of Joseph in the [Cairo Citadel](https://en.wikipedia.org/wiki/Cairo_Citadel "Cairo Citadel") at 280 feet (85 m) deep and the [Pozzo di San Patrizio](https://en.wikipedia.org/wiki/Pozzo_di_San_Patrizio "Pozzo di San Patrizio") (St. Patrick's Well) built in 1527 in [Orvieto, Italy](https://en.wikipedia.org/wiki/Orvieto "Orvieto"), at 61 metres (200 ft) deep by 13 metres (43 ft) wide[\[16\]](https://en.wikipedia.org/wiki/Well#cite_note-16) are both larger by volume. ### Driven wells \[[edit](https://en.wikipedia.org/w/index.php?title=Well&action=edit&section=4 "Edit section: Driven wells")\] Driven wells may be very simply created in unconsolidated material with a well hole structure, which consists of a hardened drive point and a screen (perforated pipe). The point is simply hammered into the ground, usually with a tripod and driver, with pipe sections added as needed. A driver is a weighted pipe that slides over the pipe being driven and is repeatedly dropped on it. When [groundwater](https://en.wikipedia.org/wiki/Groundwater "Groundwater") is encountered, the well is washed of sediment and a pump installed.[\[17\]](https://en.wikipedia.org/wiki/Well#cite_note-17) ### Drilled wells \[[edit](https://en.wikipedia.org/w/index.php?title=Well&action=edit&section=5 "Edit section: Drilled wells")\] Further information: [Well drilling](https://en.wikipedia.org/wiki/Well_drilling "Well drilling") and [Borewells in India](https://en.wikipedia.org/wiki/Borewells_in_India "Borewells in India") Drilled wells are constructed using various types of drilling machines, such as top-head rotary, table rotary, or cable tool, which all use drilling stems that rotate to cut into the formation, thus the term "drilling." Drilled wells can be excavated by simple hand drilling methods (augering, sludging, jetting, driving, hand percussion) or machine drilling (auger, rotary, percussion, down the hole hammer). Deep rock rotary drilling method is most common. Rotary can be used in 90% of formation types (consolidated). Drilled wells can get water from a much deeper level than dug wells can − often down to several hundred metres.[\[18\]](https://en.wikipedia.org/wiki/Well#cite_note-18) Drilled wells with electric pumps are used throughout the world, typically in rural or sparsely populated areas, though many urban areas are supplied partly by municipal wells. Most shallow well drilling machines are mounted on large trucks, trailers, or tracked vehicle carriages. Water wells typically range from 3 to 18 metres (10–60 ft) deep, but in some areas it can go deeper than 900 metres (3,000 ft).\[[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed "Wikipedia:Citation needed")\] [![](https://upload.wikimedia.org/wikipedia/commons/thumb/5/59/Well_spudder_8606.jpg/250px-Well_spudder_8606.jpg)](https://en.wikipedia.org/wiki/File:Well_spudder_8606.jpg) [Cable tool](https://en.wikipedia.org/wiki/Drilling_rig#Cable_tool_drilling "Drilling rig") water well drilling rig in [Kimball, West Virginia](https://en.wikipedia.org/wiki/Kimball,_West_Virginia "Kimball, West Virginia") [![](https://upload.wikimedia.org/wikipedia/commons/thumb/e/e2/AquaBellaPickard-v.jpg/250px-AquaBellaPickard-v.jpg)](https://en.wikipedia.org/wiki/File:AquaBellaPickard-v.jpg) Israeli geologist [Leo Picard](https://en.wikipedia.org/wiki/Leo_Picard "Leo Picard") (white shirt) inspects a drilled water well outside the depopulated Palestinian village of [Bayt Naqquba](https://en.wikipedia.org/wiki/Bayt_Naqquba "Bayt Naqquba") Rotary drilling machines use a segmented steel drilling string, typically made up of 3m (10ft), 6 m (20 ft) to 8m (26ft) sections of steel tubing that are threaded together, with a [bit](https://en.wikipedia.org/wiki/Drill_bit#Well_drilling_bits "Drill bit") or other drilling device at the bottom end. Some rotary drilling machines are designed to install (by driving or drilling) a steel casing into the well in conjunction with the drilling of the actual bore hole. Air and/or water is used as a circulation fluid to displace cuttings and cool bits during the drilling. Another form of rotary-style drilling, termed mud rotary, makes use of a specially made mud, or drilling fluid, which is constantly being altered during the drill so that it can consistently create enough hydraulic pressure to hold the side walls of the bore hole open, regardless of the presence of a casing in the well. Typically, boreholes drilled into solid rock are not cased until after the drilling process is completed, regardless of the machinery used. The oldest form of drilling machinery is the [cable tool](https://en.wikipedia.org/wiki/Drilling_rig#Cable_tool_drilling "Drilling rig"), still used today. Specifically designed to raise and lower a bit into the bore hole, the spudding of the drill causes the bit to be raised and dropped onto the bottom of the hole, and the design of the cable causes the bit to twist at approximately 1⁄4 revolution per drop, thereby creating a drilling action. Unlike rotary drilling, cable tool drilling requires the drilling action to be stopped so that the bore hole can be bailed or emptied of drilled cuttings. Cable tool drilling rigs are rare as they tend to be 10x slower to drill through materials compared to similar diameter rotary air or rotary mud equipped rigs. Drilled wells are usually cased with a factory-made pipe, typically [steel](https://en.wikipedia.org/wiki/Steel "Steel") (in air rotary or cable tool drilling) or [plastic](https://en.wikipedia.org/wiki/Plastic "Plastic")/[PVC](https://en.wikipedia.org/wiki/PVC "PVC") (in mud rotary wells, also present in wells drilled into solid rock). The casing is constructed by welding, either chemically or thermally, segments of casing together. If the casing is installed during the drilling, most drills will drive the casing into the ground as the bore hole advances, while some newer machines will actually allow for the casing to be rotated and drilled into the formation in a similar manner as the bit advancing just below. PVC or plastic is typically solvent welded and then lowered into the drilled well, vertically stacked with their ends nested and either glued or splined together. The sections of casing are usually 6 metres (20 ft) or more in length, and 4 to 12 in (10 to 30 cm) in diameter, depending on the intended use of the well and local groundwater conditions. Surface contamination of wells in the United States is typically controlled by the use of a surface seal. A large hole is drilled to a predetermined depth or to a confining formation (clay or bedrock, for example), and then a smaller hole for the well is completed from that point forward. The well is typically cased from the surface down into the smaller hole with a casing that is the same diameter as that hole. The annular space between the large bore hole and the smaller casing is filled with [bentonite clay](https://en.wikipedia.org/wiki/Bentonite_clay "Bentonite clay"), concrete, or other sealant material. This creates an impermeable seal from the surface to the next confining layer that keeps contaminants from traveling down the outer sidewalls of the casing or borehole and into the [aquifer](https://en.wikipedia.org/wiki/Aquifer "Aquifer"). In addition, wells are typically capped with either an engineered well cap or seal that vents air through a screen into the well, but keeps insects, small animals, and unauthorized persons from accessing the well. At the bottom of wells, based on formation, a screening device, filter pack, slotted casing, or open bore hole is left to allow the flow of water into the well. Constructed screens are typically used in unconsolidated formations (sands, gravels, etc.), allowing water and a percentage of the formation to pass through the screen. Allowing some material to pass through creates a large area filter out of the rest of the formation, as the amount of material present to pass into the well slowly decreases and is removed from the well. Rock wells are typically cased with a PVC liner/casing and screen or slotted casing at the bottom, this is mostly present just to keep rocks from entering the pump assembly. Some wells use a filter pack method, where an undersized screen or slotted casing is placed inside the well and a filter medium is packed around the screen, between the screen and the borehole or casing. This allows the water to be filtered of unwanted materials before entering the well and pumping zone. - [![An automated water well system powered by a jet-pump](https://upload.wikimedia.org/wikipedia/en/thumb/8/8e/Jet-pump_System.svg/120px-Jet-pump_System.svg.png)](https://en.wikipedia.org/wiki/File:Jet-pump_System.svg "An automated water well system powered by a jet-pump") An automated water well system powered by a jet-pump - [![An automated water well system powered by a submersible pump](https://upload.wikimedia.org/wikipedia/en/thumb/2/28/Submersible-pump_System.svg/120px-Submersible-pump_System.svg.png)](https://en.wikipedia.org/wiki/File:Submersible-pump_System.svg "An automated water well system powered by a submersible pump") An automated water well system powered by a submersible pump - [![A water well system with a cistern](https://upload.wikimedia.org/wikipedia/commons/thumb/f/f1/Water_System_With_Cistern.svg/120px-Water_System_With_Cistern.svg.png)](https://en.wikipedia.org/wiki/File:Water_System_With_Cistern.svg "A water well system with a cistern") A water well system with a cistern - [![A water well system with a pressurized cistern](https://upload.wikimedia.org/wikipedia/commons/thumb/8/8e/Water_System_With_Pressurized_Cistern.svg/120px-Water_System_With_Pressurized_Cistern.svg.png)](https://en.wikipedia.org/wiki/File:Water_System_With_Pressurized_Cistern.svg "A water well system with a pressurized cistern") A water well system with a pressurized cistern - [![A section of a stainless steel screen well](https://upload.wikimedia.org/wikipedia/commons/thumb/5/5d/Screen_tube.JPG/120px-Screen_tube.JPG)](https://en.wikipedia.org/wiki/File:Screen_tube.JPG "A section of a stainless steel screen well") A section of a stainless steel screen well ## Classification \[[edit](https://en.wikipedia.org/w/index.php?title=Well&action=edit&section=6 "Edit section: Classification")\] [![](https://upload.wikimedia.org/wikipedia/commons/thumb/c/c2/Water_well_types_wiki.svg/500px-Water_well_types_wiki.svg.png)](https://en.wikipedia.org/wiki/File:Water_well_types_wiki.svg) Water well types There are two broad classes of drilled-well types, based on the type of [aquifer](https://en.wikipedia.org/wiki/Aquifer "Aquifer") the well is in: - Shallow or unconfined wells are completed in the uppermost saturated aquifer at that location (the upper unconfined aquifer).\[[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed "Wikipedia:Citation needed")\] - Deep or confined wells are sunk through an impermeable stratum into an aquifer that is sandwiched between two impermeable strata (aquitards or aquicludes). The majority of deep aquifers are classified as artesian because the hydraulic head in a confined well is higher than the level of the top of the aquifer. If the hydraulic head in a confined well is higher than the land surface it is a "flowing" [artesian well](https://en.wikipedia.org/wiki/Artesian_well "Artesian well") (named after [Artois](https://en.wikipedia.org/wiki/Artois "Artois") in [France](https://en.wikipedia.org/wiki/France "France")).[\[19\]](https://en.wikipedia.org/wiki/Well#cite_note-19) [![](https://upload.wikimedia.org/wikipedia/commons/thumb/7/75/Old-fashioned_well_in_Finland.JPG/250px-Old-fashioned_well_in_Finland.JPG)](https://en.wikipedia.org/wiki/File:Old-fashioned_well_in_Finland.JPG) An old-fashioned water well in the countryside of [Utajärvi](https://en.wikipedia.org/wiki/Utaj%C3%A4rvi "Utajärvi"), [Finland](https://en.wikipedia.org/wiki/Finland "Finland") A special type of water well may be constructed adjacent to freshwater lakes or streams. Commonly called a collector well but sometimes referred to by the trade name Ranney well or [Ranney collector](https://en.wikipedia.org/wiki/Ranney_collector "Ranney collector"), this type of well involves sinking a caisson vertically below the top of the aquifer and then advancing lateral collectors out of the caisson and beneath the surface water body. Pumping from within the caisson induces infiltration of water from the surface water body into the aquifer, where it is collected by the collector well laterals and conveyed into the caisson where it can be pumped to the ground surface.\[[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed "Wikipedia:Citation needed")\] Two additional broad classes of well types may be distinguished, based on the use of the well: - production or pumping wells, are large diameter (greater than 15 cm in diameter) cased (metal, plastic, or concrete) water wells, constructed for extracting water from the aquifer by a [pump](https://en.wikipedia.org/wiki/Pump "Pump") (if the well is not [artesian](https://en.wikipedia.org/wiki/Artesian_aquifer "Artesian aquifer")).\[[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed "Wikipedia:Citation needed")\] [![](https://upload.wikimedia.org/wikipedia/commons/thumb/5/5c/Well_schematic.pdf/page1-250px-Well_schematic.pdf.jpg)](https://en.wikipedia.org/wiki/File:Well_schematic.pdf) Schematic diagram of a groundwater monitoring well - monitoring wells or [piezometers](https://en.wikipedia.org/wiki/Piezometer "Piezometer"), are often smaller diameter wells used to monitor the hydraulic head or sample the groundwater for chemical constituents. Piezometers are monitoring wells completed over a very short section of aquifer. Monitoring wells can also be completed at multiple levels, allowing discrete samples or measurements to be made at different vertical elevations at the same map location.[\[20\]](https://en.wikipedia.org/wiki/Well#cite_note-20) A water well constructed for pumping groundwater can be used passively as a monitoring well and a small diameter well can be pumped, but this distinction by use is common.\[[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed "Wikipedia:Citation needed")\] ## Siting \[[edit](https://en.wikipedia.org/w/index.php?title=Well&action=edit&section=7 "Edit section: Siting")\] Before excavation, information about the geology, water table depth, seasonal fluctuations, recharge area and rate should be found if possible. This work can be done by a [hydrogeologist](https://en.wikipedia.org/wiki/Hydrogeologist "Hydrogeologist"), or a groundwater surveyor using a variety of tools including electro-seismic surveying,[\[21\]](https://en.wikipedia.org/wiki/Well#cite_note-21) any available information from nearby wells, geologic maps, and sometimes [geophysical imaging](https://en.wikipedia.org/wiki/Geophysical_imaging "Geophysical imaging"). These professionals provide advice that is almost as accurate a driller who has experience and knowledge of nearby wells/bores and the most suitable drilling technique based on the expected target depth. ## Contamination \[[edit](https://en.wikipedia.org/w/index.php?title=Well&action=edit&section=8 "Edit section: Contamination")\] Further information: [Groundwater pollution](https://en.wikipedia.org/wiki/Groundwater_pollution "Groundwater pollution") [![](https://upload.wikimedia.org/wikipedia/commons/thumb/9/9d/Groundwater_Contamination_Latin_America_Sm.png/250px-Groundwater_Contamination_Latin_America_Sm.png)](https://en.wikipedia.org/wiki/File:Groundwater_Contamination_Latin_America_Sm.png) [Waterborne diseases](https://en.wikipedia.org/wiki/Waterborne_diseases "Waterborne diseases") can be spread via a well which is contaminated with fecal pathogens from [pit latrines](https://en.wikipedia.org/wiki/Pit_latrine "Pit latrine"). [![](https://upload.wikimedia.org/wikipedia/commons/thumb/b/b4/Cleaning_a_well_in_Yaounde.jpg/250px-Cleaning_a_well_in_Yaounde.jpg)](https://en.wikipedia.org/wiki/File:Cleaning_a_well_in_Yaounde.jpg) Man cleaning a well in [Yaoundé](https://en.wikipedia.org/wiki/Yaound%C3%A9 "Yaoundé"), [Cameroon](https://en.wikipedia.org/wiki/Cameroon "Cameroon") [![](https://upload.wikimedia.org/wikipedia/commons/thumb/b/b4/Hand_water_pump_in_India_%283382861084%29.jpg/250px-Hand_water_pump_in_India_%283382861084%29.jpg)](https://en.wikipedia.org/wiki/File:Hand_water_pump_in_India_\(3382861084\).jpg) Hand pump to pump water from a well in a village near Chennai in India, where the well water might be polluted by nearby [pit latrines](https://en.wikipedia.org/wiki/Pit_latrine "Pit latrine"). Shallow pumping wells can often supply [drinking water](https://en.wikipedia.org/wiki/Drinking_water "Drinking water") at a very low cost. However, impurities from the surface easily reach shallow sources, which leads to a greater risk of contamination for these wells compared to deeper wells. Contaminated wells can lead to the spread of various [waterborne diseases](https://en.wikipedia.org/wiki/Waterborne_diseases "Waterborne diseases"). Dug and driven wells are relatively easy to contaminate; for instance, most dug wells are unreliable in the majority of the United States.[\[22\]](https://en.wikipedia.org/wiki/Well#cite_note-CEH-CID-22) Some research has found that, in cold regions, changes in river flow and flooding caused by extreme rainfall or snowmelt can degrade well water quality.[\[23\]](https://en.wikipedia.org/wiki/Well#cite_note-23) ### Pathogens \[[edit](https://en.wikipedia.org/w/index.php?title=Well&action=edit&section=9 "Edit section: Pathogens")\] Most of the [bacteria](https://en.wikipedia.org/wiki/Bacteria "Bacteria"), [viruses](https://en.wikipedia.org/wiki/Viruses "Viruses"), [parasites](https://en.wikipedia.org/wiki/Parasite "Parasite"), and [fungi](https://en.wikipedia.org/wiki/Fungi "Fungi") that contaminate well water comes from [fecal material](https://en.wikipedia.org/wiki/Feces "Feces") from humans and other animals. Common bacterial contaminants include [E. coli](https://en.wikipedia.org/wiki/E._coli "E. coli"), [Salmonella](https://en.wikipedia.org/wiki/Salmonella "Salmonella"), [Shigella](https://en.wikipedia.org/wiki/Shigella "Shigella"), and [Campylobacter jejuni](https://en.wikipedia.org/wiki/Campylobacter_jejuni "Campylobacter jejuni"). Common viral contaminants include [norovirus](https://en.wikipedia.org/wiki/Norovirus "Norovirus"), [sapovirus](https://en.wikipedia.org/wiki/Sapovirus "Sapovirus"), [rotavirus](https://en.wikipedia.org/wiki/Rotavirus "Rotavirus"), [enteroviruses](https://en.wikipedia.org/wiki/Enterovirus "Enterovirus"), and [hepatitis A](https://en.wikipedia.org/wiki/Hepatitis_A "Hepatitis A") and [E](https://en.wikipedia.org/wiki/Hepatitis_E "Hepatitis E"). Parasites include [Giardia lamblia](https://en.wikipedia.org/wiki/Giardia_lamblia "Giardia lamblia"), [Cryptosporidium](https://en.wikipedia.org/wiki/Cryptosporidium "Cryptosporidium"), [Cyclospora cayetanensis](https://en.wikipedia.org/wiki/Cyclospora_cayetanensis "Cyclospora cayetanensis"), and [microsporidia](https://en.wikipedia.org/wiki/Microsporidia "Microsporidia").[\[22\]](https://en.wikipedia.org/wiki/Well#cite_note-CEH-CID-22) ### Chemical contamination \[[edit](https://en.wikipedia.org/w/index.php?title=Well&action=edit&section=10 "Edit section: Chemical contamination")\] Chemical contamination is a common problem with groundwater.[\[24\]](https://en.wikipedia.org/wiki/Well#cite_note-24) [Nitrates](https://en.wikipedia.org/wiki/Nitrate "Nitrate") from [sewage](https://en.wikipedia.org/wiki/Sewage "Sewage"), [sewage sludge](https://en.wikipedia.org/wiki/Sewage_sludge "Sewage sludge") or [fertilizer](https://en.wikipedia.org/wiki/Fertilizer "Fertilizer") are a particular problem for babies and young children. Pollutant chemicals include [pesticides](https://en.wikipedia.org/wiki/Pesticide "Pesticide") and [volatile organic compounds](https://en.wikipedia.org/wiki/Volatile_organic_compound "Volatile organic compound") from [gasoline](https://en.wikipedia.org/wiki/Gasoline "Gasoline"), [dry-cleaning](https://en.wikipedia.org/wiki/Dry-cleaning "Dry-cleaning"), the fuel additive [methyl tert-butyl ether](https://en.wikipedia.org/wiki/Methyl_tert-butyl_ether "Methyl tert-butyl ether") (MTBE), and [perchlorate](https://en.wikipedia.org/wiki/Perchlorate "Perchlorate") from rocket fuel, airbag inflators, and other artificial and natural sources.\[[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed "Wikipedia:Citation needed")\] Several minerals are also contaminants, including [lead](https://en.wikipedia.org/wiki/Lead "Lead") leached from brass fittings or old lead pipes, [chromium VI](https://en.wikipedia.org/wiki/Chromium_VI "Chromium VI") from electroplating and other sources, naturally occurring [arsenic](https://en.wikipedia.org/wiki/Arsenic "Arsenic"), [radon](https://en.wikipedia.org/wiki/Radon "Radon"), and [uranium](https://en.wikipedia.org/wiki/Uranium "Uranium")—all of which can cause cancer—and naturally occurring [fluoride](https://en.wikipedia.org/wiki/Fluoride "Fluoride"), which is desirable in low quantities to prevent [tooth decay](https://en.wikipedia.org/wiki/Tooth_decay "Tooth decay"), but can cause [dental fluorosis](https://en.wikipedia.org/wiki/Dental_fluorosis "Dental fluorosis") in higher concentrations.[\[22\]](https://en.wikipedia.org/wiki/Well#cite_note-CEH-CID-22) Some chemicals are commonly present in water wells at levels that are not toxic, but can cause other problems. [Calcium](https://en.wikipedia.org/wiki/Calcium "Calcium") and [magnesium](https://en.wikipedia.org/wiki/Magnesium "Magnesium") cause what is known as [hard water](https://en.wikipedia.org/wiki/Hard_water "Hard water"), which can precipitate and clog pipes or burn out water heaters. [Iron](https://en.wikipedia.org/wiki/Iron "Iron") and [manganese](https://en.wikipedia.org/wiki/Manganese "Manganese") can appear as dark flecks that stain clothing and plumbing, and can promote the growth of [iron and manganese bacteria](https://en.wikipedia.org/wiki/Iron_bacteria "Iron bacteria") that can form slimy black colonies that clog pipes.[\[22\]](https://en.wikipedia.org/wiki/Well#cite_note-CEH-CID-22) ### Prevention \[[edit](https://en.wikipedia.org/w/index.php?title=Well&action=edit&section=11 "Edit section: Prevention")\] Further information: [Onsite sewage facility](https://en.wikipedia.org/wiki/Onsite_sewage_facility "Onsite sewage facility") The quality of the well water can be significantly increased by lining the well, sealing the well head, fitting a self-priming hand pump, constructing an apron, ensuring the area is kept clean and free from stagnant water and animals, moving sources of contamination ([pit latrines](https://en.wikipedia.org/wiki/Pit_latrine "Pit latrine"), garbage pits, [on-site sewer systems](https://en.wikipedia.org/wiki/Onsite_sewage_facility "Onsite sewage facility")) and carrying out hygiene education. The well should be cleaned with 1% chlorine solution after construction and periodically every 6 months.\[[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed "Wikipedia:Citation needed")\] Well holes should be covered to prevent loose debris, animals, animal excrement, and wind-blown foreign matter from falling into the hole and decomposing. The cover should be able to be in place at all times, including when drawing water from the well. A suspended roof over an open hole helps to some degree, but ideally the cover should be tight fitting and fully enclosing, with only a screened air vent.\[[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed "Wikipedia:Citation needed")\] Minimum distances and soil percolation requirements between sewage disposal sites and water wells need to be observed. Rules regarding the design and installation of private and municipal septic systems take all these factors into account so that nearby drinking water sources are protected. Education of the general population in society also plays an important role in protecting drinking water.\[[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed "Wikipedia:Citation needed")\] ### Mitigation \[[edit](https://en.wikipedia.org/w/index.php?title=Well&action=edit&section=12 "Edit section: Mitigation")\] Cleanup of [contaminated groundwater](https://en.wikipedia.org/wiki/Contaminated_groundwater "Contaminated groundwater") tends to be very costly. Effective [remediation of groundwater](https://en.wikipedia.org/wiki/Groundwater_remediation "Groundwater remediation") is generally very difficult. Contamination of groundwater from surface and subsurface sources can usually be dramatically reduced by correctly centering the casing during construction and filling the casing [annulus](https://en.wikipedia.org/wiki/Annulus_\(well\) "Annulus (well)") with an appropriate sealing material. The sealing material (grout) should be placed from immediately above the production zone back to surface, because, in the absence of a correctly constructed casing seal, contaminated fluid can travel into the well through the casing annulus. Centering devices are important (usually one per length of casing or at maximum intervals of 9 m) to ensure that the grouted annular space is of even thickness.\[[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed "Wikipedia:Citation needed")\] Upon the construction of a new test well, it is considered best practice to invest in a complete battery of chemical and biological tests on the well water in question. Point-of-use treatment is available for individual properties and treatment plants are often constructed for municipal water supplies that suffer from contamination. Most of these treatment methods involve the [filtration](https://en.wikipedia.org/wiki/Filtration "Filtration") of the contaminants of concern, and additional protection may be garnered by installing well-casing screens only at depths where contamination is not present.\[[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed "Wikipedia:Citation needed")\] Wellwater for personal use is often filtered with [reverse osmosis](https://en.wikipedia.org/wiki/Reverse_osmosis "Reverse osmosis") water processors; this process can remove very small particles. A simple, effective way of killing microorganisms is to bring the water to a full boil for one to three minutes, depending on location. A household well contaminated by microorganisms can initially be treated by shock chlorination using bleach, generating concentrations hundreds of times greater than found in community water systems; however, this will not fix any structural problems that led to the contamination and generally requires some expertise and testing for effective application.[\[22\]](https://en.wikipedia.org/wiki/Well#cite_note-CEH-CID-22) After the filtration process, it is common to implement an [ultraviolet](https://en.wikipedia.org/wiki/Ultraviolet_germicidal_irradiation "Ultraviolet germicidal irradiation") (UV) system to kill pathogens in the water. UV light affects the DNA of the pathogen by UV-C photons breaking through the cell wall. UV disinfection has been gaining popularity in the past decades as it is a chemical-free method of water treatment.[\[25\]](https://en.wikipedia.org/wiki/Well#cite_note-25) ## Environmental problems \[[edit](https://en.wikipedia.org/w/index.php?title=Well&action=edit&section=13 "Edit section: Environmental problems")\] A risk with the placement of water wells is [soil salination](https://en.wikipedia.org/wiki/Soil_salinity "Soil salinity") which occurs when the water table of the soil begins to drop and salt begins to accumulate as the soil begins to dry out.[\[26\]](https://en.wikipedia.org/wiki/Well#cite_note-26) Another environmental problem that is very prevalent in water well drilling is the potential for methane to seep through. ### Soil salination \[[edit](https://en.wikipedia.org/w/index.php?title=Well&action=edit&section=14 "Edit section: Soil salination")\] The potential for soil salination is a large risk when choosing the placement of water wells. Soil salination is caused when the water table of the soil drops over time and salt begins to accumulate. In turn, the increased amount of salt begins to dry the soil out. The increased level of salt in the soil can result in the degradation of soil and can be very harmful to vegetation.\[[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed "Wikipedia:Citation needed")\] ### Methane \[[edit](https://en.wikipedia.org/w/index.php?title=Well&action=edit&section=15 "Edit section: Methane")\] [Methane](https://en.wikipedia.org/wiki/Methane "Methane"), an asphyxiant, is a chemical compound that is the main component of natural gas. When methane is introduced into a confined space, it displaces oxygen, reducing oxygen concentration to a level low enough to pose a threat to humans and other aerobic organisms but still high enough for a risk of [spontaneous](https://en.wikipedia.org/wiki/Spontaneous_combustion "Spontaneous combustion") or externally caused explosion. This potential for explosion is what poses such a danger in regards to the drilling and placement of water wells.\[[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed "Wikipedia:Citation needed")\] Low levels of methane in drinking water are not considered toxic. When methane seeps into a water supply, it is commonly referred to as "methane migration". This can be caused by old natural gas wells near water well systems becoming abandoned and no longer monitored.\[[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed "Wikipedia:Citation needed")\] Lately,\[[when?](https://en.wikipedia.org/wiki/Wikipedia:Manual_of_Style/Dates_and_numbers#Chronological_items "Wikipedia:Manual of Style/Dates and numbers")\] however, the described wells/pumps are no longer very efficient and can be replaced by either [handpumps](https://en.wikipedia.org/wiki/Handpump "Handpump") or [treadle pumps](https://en.wikipedia.org/wiki/Treadle_pump "Treadle pump"). Another alternative is the use of self-dug wells, electrical deep-well pumps (for higher depths). [Appropriate technology](https://en.wikipedia.org/wiki/Appropriate_technology "Appropriate technology") organizations as [Practical Action](https://en.wikipedia.org/wiki/Practical_Action "Practical Action") are now\[[when?](https://en.wikipedia.org/wiki/Wikipedia:Manual_of_Style/Dates_and_numbers#Chronological_items "Wikipedia:Manual of Style/Dates and numbers")\] supplying information on how to build/set-up ([DIY](https://en.wikipedia.org/wiki/Do_it_yourself "Do it yourself")) handpumps and [treadle pumps](https://en.wikipedia.org/wiki/Treadle_pump "Treadle pump") in practice.[\[27\]](https://en.wikipedia.org/wiki/Well#cite_note-27)[\[28\]](https://en.wikipedia.org/wiki/Well#cite_note-28) ### PFAS/PFOS Fire fighting foam \[[edit](https://en.wikipedia.org/w/index.php?title=Well&action=edit&section=16 "Edit section: PFAS/PFOS Fire fighting foam")\] Per- and polyfluoroalkyl substances ([PFAS](https://en.wikipedia.org/wiki/Per-_and_polyfluoroalkyl_substances "Per- and polyfluoroalkyl substances") or PFASs) are a group of synthetic [organofluorine](https://en.wikipedia.org/wiki/Organofluorine_chemistry "Organofluorine chemistry") [chemical compounds](https://en.wikipedia.org/wiki/Chemical_compound "Chemical compound") that have multiple [fluorine](https://en.wikipedia.org/wiki/Fluorine "Fluorine") atoms attached to an [alkyl](https://en.wikipedia.org/wiki/Alkyl "Alkyl") chain. PFAS are a group of "forever chemicals" that spread very quickly and very far in ground water polluting it permanently. Water wells near certain airports where any foam fire fighting or training activities occurred up to 2010 are likely to be contaminated by PFAS. ## Water security \[[edit](https://en.wikipedia.org/w/index.php?title=Well&action=edit&section=17 "Edit section: Water security")\] A study concluded that of ~39 million groundwater wells 9-20% are at [high risk of running dry](https://en.wikipedia.org/wiki/Water_security "Water security") if local groundwater levels decline by less than five meters, or – as with many areas and possibly more than half of major [aquifers](https://en.wikipedia.org/wiki/Aquifer "Aquifer")[\[29\]](https://en.wikipedia.org/wiki/Well#cite_note-29) – continue to decline.[\[30\]](https://en.wikipedia.org/wiki/Well#cite_note-30)[\[31\]](https://en.wikipedia.org/wiki/Well#cite_note-31)\[[further explanation needed](https://en.wikipedia.org/wiki/Wikipedia:Please_clarify "Wikipedia:Please clarify")\] ## Society and culture \[[edit](https://en.wikipedia.org/w/index.php?title=Well&action=edit&section=18 "Edit section: Society and culture")\] See also: [Wells in the Bible](https://en.wikipedia.org/wiki/Wells_in_the_Bible "Wells in the Bible") [![](https://upload.wikimedia.org/wikipedia/commons/thumb/6/6a/22-alimenti%2C_acqua_dolce%2CTaccuino_Sanitatis%2C_Casanatense_418.jpg/250px-22-alimenti%2C_acqua_dolce%2CTaccuino_Sanitatis%2C_Casanatense_418.jpg)](https://en.wikipedia.org/wiki/File:22-alimenti,_acqua_dolce,Taccuino_Sanitatis,_Casanatense_418.jpg) Water use, [Tacuinum Sanitatis](https://en.wikipedia.org/wiki/Tacuinum_Sanitatis "Tacuinum Sanitatis"), [Biblioteca Casanatense](https://en.wikipedia.org/wiki/Biblioteca_Casanatense "Biblioteca Casanatense") (14th century) [Springs](https://en.wikipedia.org/wiki/Spring_\(hydrology\) "Spring (hydrology)") and wells have had [cultural significance](https://en.wikipedia.org/wiki/Cultural_significance "Cultural significance") since [prehistoric](https://en.wikipedia.org/wiki/Prehistoric "Prehistoric") times, leading to the foundation of towns such as [Wells](https://en.wikipedia.org/wiki/Wells,_Somerset "Wells, Somerset") and [Bath](https://en.wikipedia.org/wiki/Bath,_Somerset "Bath, Somerset") in [Somerset](https://en.wikipedia.org/wiki/Somerset "Somerset"). Interest in health benefits led to the growth of [spa towns](https://en.wikipedia.org/wiki/Spa_town "Spa town") including many with wells in their name, examples being [Llandrindod Wells](https://en.wikipedia.org/wiki/Llandrindod_Wells "Llandrindod Wells") and [Royal Tunbridge Wells](https://en.wikipedia.org/wiki/Royal_Tunbridge_Wells "Royal Tunbridge Wells").[\[32\]](https://en.wikipedia.org/wiki/Well#cite_note-Burr-32) [Eratosthenes](https://en.wikipedia.org/wiki/Eratosthenes "Eratosthenes") is sometimes claimed to have used a well in his calculation of the [Earth's circumference](https://en.wikipedia.org/wiki/Earth%27s_circumference "Earth's circumference"); however, this is just a simplification used in a shorter explanation of [Cleomedes](https://en.wikipedia.org/wiki/Cleomedes "Cleomedes"), since Eratosthenes had used a more elaborate and precise method.[\[33\]](https://en.wikipedia.org/wiki/Well#cite_note-russo273277-33) Many incidents in the [Bible](https://en.wikipedia.org/wiki/Bible "Bible") take place around wells, such as the finding of a wife for [Isaac](https://en.wikipedia.org/wiki/Isaac "Isaac") in [Genesis](https://en.wikipedia.org/wiki/Book_of_Genesis "Book of Genesis") and [Jesus](https://en.wikipedia.org/wiki/Jesus "Jesus")'s talk with the Samaritan woman in the [Gospels](https://en.wikipedia.org/wiki/Gospels "Gospels").[\[34\]](https://en.wikipedia.org/wiki/Well#cite_note-34) ## A simple model for water well recovery \[[edit](https://en.wikipedia.org/w/index.php?title=Well&action=edit&section=19 "Edit section: A simple model for water well recovery")\] [![](https://upload.wikimedia.org/wikipedia/commons/thumb/5/57/Well_Recovery_diagram.jpg/250px-Well_Recovery_diagram.jpg)](https://en.wikipedia.org/wiki/File:Well_Recovery_diagram.jpg) Diagram of a water well partially filled to level z with the top of the aquifer at zT For a well with impermeable walls, the water in the well is resupplied from the bottom of the well. The rate at which water flows into the well will depend on the pressure difference between the ground water at the well bottom and the well water at the well bottom. The pressure of a column of water of height z will be equal to the weight of the water in the column divided by the cross-sectional area of the column, so the pressure of the ground water a distance zT below the top of the water table will be: P g \= ρ g z T {\\displaystyle P\_{g}=\\rho \\,g\\,z\_{T}} ![{\\displaystyle P\_{g}=\\rho \\,g\\,z\_{T}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/638cbf760d9b102d42a0fe61424cfbb84eb644ed) where ρ is the mass density of the water and g is the acceleration due to gravity. When the water in the well is below the water table level, the pressure at the bottom of the well due to the water in the well will be less than Pg and water will be forced into the well. Referring to the diagram, if z is the distance from the bottom of the well to the well water level and zT is the distance from the bottom of the well to the top of the water table, the pressure difference will be: Δ P \= ρ g ( z T − z ) {\\displaystyle \\Delta P=\\rho \\,g\\,(z\_{T}-z)} ![{\\displaystyle \\Delta P=\\rho \\,g\\,(z\_{T}-z)}](https://wikimedia.org/api/rest_v1/media/math/render/svg/311a95e84de02b5c6e319eedd8feb50ea181063e) Applying [Darcy's law](https://en.wikipedia.org/wiki/Darcy%27s_law "Darcy's law"), the volume rate (F) at which water is forced into the well will be proportional to this pressure difference: Δ P \= R F {\\displaystyle \\Delta P=R\\,F} ![{\\displaystyle \\Delta P=R\\,F}](https://wikimedia.org/api/rest_v1/media/math/render/svg/5786632d6b2bb052677675191ea1e572c14aaa15) where R is the resistance to the flow, which depends on the well cross section, the pressure gradient at the bottom of the well, and the characteristics of the substrate at the well bottom. (e.g., porosity). The volume flow rate into the well can be written as a function of the rate of change of the well water level: F \= A d z d t {\\displaystyle F=A{\\frac {dz}{dt}}} ![{\\displaystyle F=A{\\frac {dz}{dt}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/2a739564c0695861c243527e15701b5380b474c5) Combining the above three equations yields a simple differential equation in z: R A d z d t \= ρ g ( z T − z ) {\\displaystyle RA{\\frac {dz}{dt}}=\\rho g(z\_{T}-z)} ![{\\displaystyle RA{\\frac {dz}{dt}}=\\rho g(z\_{T}-z)}](https://wikimedia.org/api/rest_v1/media/math/render/svg/17afdd8ee77364f91732322618429ae09d2a4fe0) which may be solved: z \= z T − ( z T − z 0 ) e − t / τ {\\displaystyle z=z\_{T}-(z\_{T}-z\_{0})e^{-t/\\tau }} ![{\\displaystyle z=z\_{T}-(z\_{T}-z\_{0})e^{-t/\\tau }}](https://wikimedia.org/api/rest_v1/media/math/render/svg/16df3ea8a895dd6cd73a39111821a175b1c5d98d) where z0 is the well water level at time t=0 and τ is the well time constant: τ \= R A ρ g {\\displaystyle \\tau ={\\frac {RA}{\\rho g}}} ![{\\displaystyle \\tau ={\\frac {RA}{\\rho g}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/01cd2f59d9c030817d81d1c8ab981b070faa8d3b) Note that if dz/dt for a depleted well can be measured, it will be equal to z T / τ {\\displaystyle z\_{T}/\\tau } ![{\\displaystyle z\_{T}/\\tau }](https://wikimedia.org/api/rest_v1/media/math/render/svg/b72aa8e3c928e0d99f543788380c18fe540ac987) and the time constant τ can be calculated. According to the above model, it will take an infinite amount of time for a well to fully recover, but if we consider a well that is 99% recovered to be "practically" recovered, the time for a well to practically recover from a level at z will be: T r \= τ ln ⁡ ( 1 − z / z T 1 − 0\.99 ) {\\displaystyle T\_{r}=\\tau \\ln \\left({\\frac {1-z/z\_{T}}{1-0.99}}\\right)} ![{\\displaystyle T\_{r}=\\tau \\ln \\left({\\frac {1-z/z\_{T}}{1-0.99}}\\right)}](https://wikimedia.org/api/rest_v1/media/math/render/svg/3db7a070422bcbfe86695fa9ed06fb1261b8d06a) For a well that is fully depleted (z=0) it would take a time of about 4\.6 τ to practically recover. The above model does not take into account the depletion of the aquifer due to the pumping which lowered the well water level (See [aquifer test](https://en.wikipedia.org/wiki/Aquifer_test "Aquifer test") and [groundwater flow equation](https://en.wikipedia.org/wiki/Groundwater_flow_equation "Groundwater flow equation")). Also, practical wells may have impermeable walls only up to, but not including the bedrock, which will give a larger surface area for water to enter the well.[\[35\]](https://en.wikipedia.org/wiki/Well#cite_note-Humboldt-35)[\[36\]](https://en.wikipedia.org/wiki/Well#cite_note-Inspectapedia-36) ## Similar and related water structures \[[edit](https://en.wikipedia.org/w/index.php?title=Well&action=edit&section=20 "Edit section: Similar and related water structures")\] - Types of ancient wells - [Brick-lined well](https://en.wikipedia.org/wiki/Brick-lined_well "Brick-lined well") - [Castle well](https://en.wikipedia.org/wiki/Castle_well "Castle well"), for use in the castle - [Cistern](https://en.wikipedia.org/wiki/Cistern "Cistern"), ancient Greek - [Stepwell](https://en.wikipedia.org/wiki/Stepwell "Stepwell"), ancient India - Modern construction techniques - [Baptist well drilling](https://en.wikipedia.org/wiki/Baptist_well_drilling "Baptist well drilling"), simple technique - [Rodriguez well](https://en.wikipedia.org/wiki/Rodriguez_well "Rodriguez well"), for harvesting drinking water in polar regions - [Spring supply](https://en.wikipedia.org/wiki/Spring_supply "Spring supply"), piped water supply from the well - Uses - [Holy well](https://en.wikipedia.org/wiki/Holy_well "Holy well"), sacred wells in various religions - [Abraham's well](https://en.wikipedia.org/wiki/Abraham%27s_well "Abraham's well"), sacred well in Israel - [Ghat](https://en.wikipedia.org/wiki/Ghat "Ghat"), sacred in Hinduism and Buddhism - - Drainage and irrigation - [Drainage by wells](https://en.wikipedia.org/wiki/Drainage_by_wells "Drainage by wells") - [Shadoof](https://en.wikipedia.org/wiki/Shadoof "Shadoof"), an irrigation tool that is used to lift water from a water source onto land or into another waterway or basin - - Washing - [Lavoir](https://en.wikipedia.org/wiki/Lavoir "Lavoir"), public place for washing clothes. ## See also \[[edit](https://en.wikipedia.org/w/index.php?title=Well&action=edit&section=21 "Edit section: See also")\] - [Fossil water](https://en.wikipedia.org/wiki/Fossil_water "Fossil water") - [History of water supply and sanitation](https://en.wikipedia.org/wiki/History_of_water_supply_and_sanitation "History of water supply and sanitation") - [Ancient water conservation techniques](https://en.wikipedia.org/wiki/Johad#Similar "Johad") - [Self-supply of water and sanitation](https://en.wikipedia.org/wiki/Self-supply_of_water_and_sanitation "Self-supply of water and sanitation") ## References \[[edit](https://en.wikipedia.org/w/index.php?title=Well&action=edit&section=22 "Edit section: References")\] 1. [^](https://en.wikipedia.org/wiki/Well#cite_ref-1) Peltenburg, Edgar (2012). "East Mediterranean water wells of the 9th–7th millennium BC". In Klimscha, Florian (ed.). Wasserwirtschaftliche Innovationen im archäologischen Kontext. Von den prähistorischen Anfängen bis zu den Metropolen der Antike. Rahden/Westfalia: Leidorf. pp. 69–82\. 2. [^](https://en.wikipedia.org/wiki/Well#cite_ref-2) Galili, Ehud; Nir, Yaacov (1993). "The submerged Pre-Pottery Neolithic water well of Atlit-Yam, northern Israel, and its palaeoenvironmental implications". The Holocene. 3 (3): 265–270\. [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[1993Holoc...3..265G](https://ui.adsabs.harvard.edu/abs/1993Holoc...3..265G). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1177/095968369300300309](https://doi.org/10.1177%2F095968369300300309). [S2CID](https://en.wikipedia.org/wiki/S2CID_\(identifier\) "S2CID (identifier)") [130032420](https://api.semanticscholar.org/CorpusID:130032420). 3. [^](https://en.wikipedia.org/wiki/Well#cite_ref-3) Rybníček, Michal; Kočár, Petr; Muigg, Bernhard; Peška, Jaroslav; Sedláček, Radko; Tegel, Willy; Kolář, Tomáš (2020). ["World's oldest dendrochronologically dated archaeological wood construction"](https://www.sciencedirect.com/science/article/pii/S0305440320300066). Journal of Archaeological Science. 115 105082. [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[2020JArSc.115j5082R](https://ui.adsabs.harvard.edu/abs/2020JArSc.115j5082R). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1016/j.jas.2020.105082](https://doi.org/10.1016%2Fj.jas.2020.105082). [S2CID](https://en.wikipedia.org/wiki/S2CID_\(identifier\) "S2CID (identifier)") [213707193](https://api.semanticscholar.org/CorpusID:213707193). 4. [^](https://en.wikipedia.org/wiki/Well#cite_ref-4) ["Kückhovener Brunnen – Dorfgemeinschaft Kückhoven E. V."](http://www.dorfgemeinschaft-kueckhoven.de/unser-dorf/kueckhovener-brunnen/) \[[permanent dead link](https://en.wikipedia.org/wiki/Wikipedia:Link_rot "Wikipedia:Link rot")\] 5. [^](https://en.wikipedia.org/wiki/Well#cite_ref-5) Tegel W, Elburg R, Hakelberg D, Stäuble H, Büntgen U (2012). ["Early Neolithic Water Wells Reveal the World's Oldest Wood Architecture"](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3526582). PLOS ONE. 7 (12) e51374. [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[2012PLoSO...751374T](https://ui.adsabs.harvard.edu/abs/2012PLoSO...751374T). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1371/journal.pone.0051374](https://doi.org/10.1371%2Fjournal.pone.0051374). [PMC](https://en.wikipedia.org/wiki/PMC_\(identifier\) "PMC (identifier)") [3526582](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3526582). [PMID](https://en.wikipedia.org/wiki/PMID_\(identifier\) "PMID (identifier)") [23284685](https://pubmed.ncbi.nlm.nih.gov/23284685). 6. ^ [*a](https://en.wikipedia.org/wiki/Well#cite_ref-Kuhn2004_6-0) [b](https://en.wikipedia.org/wiki/Well#cite_ref-Kuhn2004_6-1) Kuhn, Oliver (2004-06-30). ["Ancient Chinese Drilling"](https://csegrecorder.com/articles/view/ancient-chinese-drilling). Canadian Society of Exploration Geophysicists. 29* (6). 7. ^ [*a](https://en.wikipedia.org/wiki/Well#cite_ref-Chang2012_7-0) [b](https://en.wikipedia.org/wiki/Well#cite_ref-Chang2012_7-1) Chang, Mingteh (2012). Forest Hydrology: An Introduction to Water and Forests* (3rd ed.). CRC Press (published November 1, 2012). p. 31. [ISBN](https://en.wikipedia.org/wiki/ISBN_\(identifier\) "ISBN (identifier)") [978-1-4398-7994-8](https://en.wikipedia.org/wiki/Special:BookSources/978-1-4398-7994-8 "Special:BookSources/978-1-4398-7994-8") . 8. [^](https://en.wikipedia.org/wiki/Well#cite_ref-8) Koon, Wee Kek (July 25, 2015). ["How the ancient Chinese looked after their drinking water"](https://www.scmp.com/magazines/post-magazine/article/1843012/how-ancient-chinese-looked-after-their-drinking-water). South China Morning Post. 9. [^](https://en.wikipedia.org/wiki/Well#cite_ref-9) ["Sakieh explication/difference vs Sakia"](http://www.britannica.com/eb/topic-518730/sakia). Britannica.com. Retrieved 2011-12-19. 10. [^](https://en.wikipedia.org/wiki/Well#cite_ref-10) ["Sakia explication"](http://www.britannica.com/eb/article-9001226/sakia#271043.hook). Britannica.com. Retrieved 2011-12-19. 11. [^](https://en.wikipedia.org/wiki/Well#cite_ref-11) ["Stone Age wells found in Cyprus"](https://news.bbc.co.uk/2/hi/europe/8118318.stm). BBC News. 12. [^](https://en.wikipedia.org/wiki/Well#cite_ref-12) Ashkenazi, Eli (November 9, 2012). ["Ancient Well Reveals Secrets of First Jezreel Valley Farmers"](https://www.haaretz.com/israel-news/ancient-well-reveals-secrets-of-first-jezreel-valley-farmers-1.476288). Haaretz. 13. [^](https://en.wikipedia.org/wiki/Well#cite_ref-ASTM_13-0) ["ASTM International – Standards Worldwide"](https://web.archive.org/web/20200801082953/https://www.astm.org/COMMIT/D02/to1899_index.html). www.astm.org. Archived from [the original](https://www.astm.org/COMMIT/D02/to1899_index.html) on 2020-08-01. Retrieved 2019-02-01. 14. [^](https://en.wikipedia.org/wiki/Well#cite_ref-EB1911_14-0) Joseph P. Riva Jr. and Gordon I. Atwater. ["petroleum"](http://www.britannica.com/EBchecked/topic/454269/petroleum). [Encyclopædia Britannica](https://en.wikipedia.org/wiki/Encyclop%C3%A6dia_Britannica "Encyclopædia Britannica"). Retrieved 2008-06-30. 15. [^](https://en.wikipedia.org/wiki/Well#cite_ref-15) ["Woodingdean Well"](http://www.mybrightonandhove.org.uk/page_id__6948_path__0p115p1224p597p.aspx). 2005. Retrieved 26 Jan 2010. 16. [^](https://en.wikipedia.org/wiki/Well#cite_ref-16) ["St. Patrick's Well"](http://www.umbriatravel.com/Orvieto/en/itineraries_Orvieto.asp). Umbriatravel.com. Retrieved 2011-12-19. \[[permanent dead link](https://en.wikipedia.org/wiki/Wikipedia:Link_rot "Wikipedia:Link rot")\] 17. [^](https://en.wikipedia.org/wiki/Well#cite_ref-17) ["How I drill a Well."](https://books.google.com/books?id=oiEDAAAAMBAJ&dq=popular+science+1930&pg=-PA77) Popular Science, April 1952, pp. 177–181. 18. [^](https://en.wikipedia.org/wiki/Well#cite_ref-18) Association), NKBA (National Kitchen and Bath (2013-10-29). [Kitchen & Bath Residential Construction and Systems](https://books.google.com/books?id=CVTjAQAAQBAJ&q=Drilled+wells+can+get+water+from+a+much+deeper+level+than+dug+wells+can%E2%80%94often+down+to+several+hundred+metres.&pg=PA178). John Wiley & Sons. [ISBN](https://en.wikipedia.org/wiki/ISBN_\(identifier\) "ISBN (identifier)") [978-1-118-71104-0](https://en.wikipedia.org/wiki/Special:BookSources/978-1-118-71104-0 "Special:BookSources/978-1-118-71104-0") . 19. [^](https://en.wikipedia.org/wiki/Well#cite_ref-19) ["Artesian Water and Artesian Wells \\| U.S. Geological Survey"](https://www.usgs.gov/water-science-school/science/artesian-water-and-artesian-wells). www.usgs.gov. 2018-10-09. Retrieved 2026-03-23. 20. [^](https://en.wikipedia.org/wiki/Well#cite_ref-20) Arnold, L.R.; Flynn, J.L.; Paschke, S.S. (2009-10-20). ["Design and installation of a groundwater monitoring-well network in the High Plains aquifer, Colorado"](https://pubs.usgs.gov/publication/ds456). USGS Report. Data Series. U.S. Geological Survey: 5. [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[2009usgs.rept....5A](https://ui.adsabs.harvard.edu/abs/2009usgs.rept....5A). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.3133/ds456](https://doi.org/10.3133%2Fds456). Retrieved 27 May 2024. 21. [^](https://en.wikipedia.org/wiki/Well#cite_ref-21) Du Preez, Michael. ["ELECTRO-SEISMIC SURVEYS APPLIED TO MODDELING OF GROUNDWATER FLOW SYSTEMS"](https://web.archive.org/web/20110531163202/http://aquamap.co.nz/uploads/pdfs/ELECTRO-SEISMIC%20SURVEYS%20APPLIED%20TO%20MODELING%20OF%20GROUNDWATER%20FLOW.pdf) (PDF). Bloemfontein, South Africa. Archived from [the original](http://aquamap.co.nz/uploads/pdfs/ELECTRO-SEISMIC%20SURVEYS%20APPLIED%20TO%20MODELING%20OF%20GROUNDWATER%20FLOW.pdf) (PDF) on 31 May 2011. Retrieved 21 April 2011. 22. ^ [*a](https://en.wikipedia.org/wiki/Well#cite_ref-CEH-CID_22-0) [b](https://en.wikipedia.org/wiki/Well#cite_ref-CEH-CID_22-1) [c](https://en.wikipedia.org/wiki/Well#cite_ref-CEH-CID_22-2) [d](https://en.wikipedia.org/wiki/Well#cite_ref-CEH-CID_22-3) [e](https://en.wikipedia.org/wiki/Well#cite_ref-CEH-CID_22-4) Committee on Environmental Health; Committee on Infectious Diseases (2009). ["Drinking water from private wells and risks to children"](https://doi.org/10.1542%2Fpeds.2009-0751). [Pediatrics](https://en.wikipedia.org/wiki/Pediatrics_\(journal\) "Pediatrics (journal)"). 123* (6): 1599–1605\. [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1542/peds.2009-0751](https://doi.org/10.1542%2Fpeds.2009-0751). [PMID](https://en.wikipedia.org/wiki/PMID_\(identifier\) "PMID (identifier)") [19482772](https://pubmed.ncbi.nlm.nih.gov/19482772). 23. [^](https://en.wikipedia.org/wiki/Well#cite_ref-23) Wiebe, Andrew J.; Rudolph, David L.; Pasha, Ehsan; Brook, Jacqueline M.; Christie, Mike; Menkveld, Paul G. (2021). ["Impacts of Event-Based Recharge on the Vulnerability of Public Supply Wells"](https://doi.org/10.3390%2Fsu13147695). Sustainability. 13 (14): 7695. [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[2021Sust...13.7695W](https://ui.adsabs.harvard.edu/abs/2021Sust...13.7695W). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.3390/su13147695](https://doi.org/10.3390%2Fsu13147695). [ISSN](https://en.wikipedia.org/wiki/ISSN_\(identifier\) "ISSN (identifier)") [2071-1050](https://search.worldcat.org/issn/2071-1050). 24. [^](https://en.wikipedia.org/wiki/Well#cite_ref-24) Association, American Water Works (2003). [Water Sources](https://books.google.com/books?id=iOIdnO03cgEC&q=Chemical+contamination+is+a+common+problem+with+groundwater&pg=PA141). American Water Works Association. [ISBN](https://en.wikipedia.org/wiki/ISBN_\(identifier\) "ISBN (identifier)") [978-1-58321-229-5](https://en.wikipedia.org/wiki/Special:BookSources/978-1-58321-229-5 "Special:BookSources/978-1-58321-229-5") . 25. [^](https://en.wikipedia.org/wiki/Well#cite_ref-25) Meulemans, C. C. E. (1987-09-01). "The Basic Principles of UV–Disinfection of Water". Ozone: Science & Engineering. 9 (4): 299–313\. [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[1987OzSE....9..299M](https://ui.adsabs.harvard.edu/abs/1987OzSE....9..299M). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1080/01919518708552146](https://doi.org/10.1080%2F01919518708552146). [ISSN](https://en.wikipedia.org/wiki/ISSN_\(identifier\) "ISSN (identifier)") [0191-9512](https://search.worldcat.org/issn/0191-9512). 26. [^](https://en.wikipedia.org/wiki/Well#cite_ref-26) ["Soil salination by placement of water wells mentioned in India"](https://web.archive.org/web/20090522010539/http://ngm.nationalgeographic.com/2009/06/cheap-food/bourne-text/1). Ngm.nationalgeographic.com. 2002-10-17. Archived from [the original](http://ngm.nationalgeographic.com/2009/06/cheap-food/bourne-text/1) on May 22, 2009. Retrieved 2011-12-19. 27. [^](https://en.wikipedia.org/wiki/Well#cite_ref-27) ["Practical Answers – Handpumps"](http://practicalaction.org/practicalanswers/product_info.php?products_id=198). Practicalaction.org. Retrieved 2011-12-19. 28. [^](https://en.wikipedia.org/wiki/Well#cite_ref-28) ["Treadle pump"](http://dev.practicalaction.org/?id=appeal_nepalpump). Dev.practicalaction.org. Retrieved 2011-12-19. 29. [^](https://en.wikipedia.org/wiki/Well#cite_ref-29) Famiglietti, James S.; Ferguson, Grant (23 April 2021). ["The hidden crisis beneath our feet"](https://www.science.org/doi/10.1126/science.abh2867). Science. 372 (6540): 344–345\. [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[2021Sci...372..344F](https://ui.adsabs.harvard.edu/abs/2021Sci...372..344F). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1126/science.abh2867](https://doi.org/10.1126%2Fscience.abh2867). [PMID](https://en.wikipedia.org/wiki/PMID_\(identifier\) "PMID (identifier)") [33888627](https://pubmed.ncbi.nlm.nih.gov/33888627). [S2CID](https://en.wikipedia.org/wiki/S2CID_\(identifier\) "S2CID (identifier)") [233353241](https://api.semanticscholar.org/CorpusID:233353241). Retrieved 10 May 2021. 30. [^](https://en.wikipedia.org/wiki/Well#cite_ref-30) ["The largest assessment of global groundwater wells finds many are at risk of drying up"](https://www.sciencedaily.com/releases/2021/04/210423130101.htm). ScienceDaily. Retrieved 10 May 2021. 31. [^](https://en.wikipedia.org/wiki/Well#cite_ref-31) Jasechko, Scott; Perrone, Debra (23 April 2021). ["Global groundwater wells at risk of running dry"](https://www.science.org/doi/10.1126/science.abc2755). Science. 372 (6540): 418–421\. [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[2021Sci...372..418J](https://ui.adsabs.harvard.edu/abs/2021Sci...372..418J). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1126/science.abc2755](https://doi.org/10.1126%2Fscience.abc2755). [ISSN](https://en.wikipedia.org/wiki/ISSN_\(identifier\) "ISSN (identifier)") [0036-8075](https://search.worldcat.org/issn/0036-8075). [PMID](https://en.wikipedia.org/wiki/PMID_\(identifier\) "PMID (identifier)") [33888642](https://pubmed.ncbi.nlm.nih.gov/33888642). [S2CID](https://en.wikipedia.org/wiki/S2CID_\(identifier\) "S2CID (identifier)") [233353207](https://api.semanticscholar.org/CorpusID:233353207). Retrieved 10 May 2021. 32. [^](https://en.wikipedia.org/wiki/Well#cite_ref-Burr_32-0) Burr, Thomas Benge (1766). [The History of Tunbridge Wells](https://web.archive.org/web/20210131221739/https://theweald.org/d10.asp?BookId=burr000). London. Archived from [the original](http://theweald.org/bk.asp?bookid=burr000) on 2021-01-31. Retrieved 2019-10-09. 33. [^](https://en.wikipedia.org/wiki/Well#cite_ref-russo273277_33-0) [Russo, Lucio](https://en.wikipedia.org/wiki/Lucio_Russo "Lucio Russo") (2004). The Forgotten Revolution. Berlin: Springer. pp. 273–277\. 34. [^](https://en.wikipedia.org/wiki/Well#cite_ref-34) Bromiley, Geoffrey W. (1982), International Standard Bible Encyclopedia: E-J, Wm. B. Eerdmans Publishing, p. 955, [ISBN](https://en.wikipedia.org/wiki/ISBN_\(identifier\) "ISBN (identifier)") [978-0-8028-3782-0](https://en.wikipedia.org/wiki/Special:BookSources/978-0-8028-3782-0 "Special:BookSources/978-0-8028-3782-0") 35. [^](https://en.wikipedia.org/wiki/Well#cite_ref-Humboldt_35-0) ["Well Flow Equations"](https://geology.humboldt.edu/courses/geology556/556_handouts/well_flow_equations.pdf) (PDF). Cal Poly Humboldt, Department of Geology. Retrieved June 13, 2022. 36. [^](https://en.wikipedia.org/wiki/Well#cite_ref-Inspectapedia_36-0) ["How Much Water Can the Well Deliver"](https://inspectapedia.com/water/Well_Flow_Rate.php). Inspectapedia. Retrieved June 13, 2022. ### Bibliography \[[edit](https://en.wikipedia.org/w/index.php?title=Well&action=edit&section=23 "Edit section: Bibliography")\] - Driscoll, F. (1986). Groundwater and Wells. [St. Paul](https://en.wikipedia.org/wiki/St._Paul,_MN "St. Paul, MN"): Johnson Filtration Systems. [ISBN](https://en.wikipedia.org/wiki/ISBN_\(identifier\) "ISBN (identifier)") [978-0-9616456-0-1](https://en.wikipedia.org/wiki/Special:BookSources/978-0-9616456-0-1 "Special:BookSources/978-0-9616456-0-1") . - Raymond Rowles (1995). Drilling for Water (2nd ed.). Avebury, Cranfield University. [ISBN](https://en.wikipedia.org/wiki/ISBN_\(identifier\) "ISBN (identifier)") [1-85628-984-2](https://en.wikipedia.org/wiki/Special:BookSources/1-85628-984-2 "Special:BookSources/1-85628-984-2") . ## External links \[[edit](https://en.wikipedia.org/w/index.php?title=Well&action=edit&section=24 "Edit section: External links")\] [![Wikimedia Commons logo](https://upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/40px-Commons-logo.svg.png)](https://en.wikipedia.org/wiki/File:Commons-logo.svg) Wikimedia Commons has media related to [Water wells](https://commons.wikimedia.org/wiki/Category:Water_wells "commons:Category:Water wells"). [![Wikisource logo](https://upload.wikimedia.org/wikipedia/commons/thumb/4/4c/Wikisource-logo.svg/40px-Wikisource-logo.svg.png)](https://en.wikipedia.org/wiki/File:Wikisource-logo.svg) [Wikisource](https://en.wikipedia.org/wiki/Wikisource "Wikisource") has the text of the [1911 Encyclopædia Britannica](https://en.wikipedia.org/wiki/Encyclop%C3%A6dia_Britannica_Eleventh_Edition "Encyclopædia Britannica Eleventh Edition") article "[Well](https://en.wikisource.org/wiki/1911_Encyclop%C3%A6dia_Britannica/Well "wikisource:1911 Encyclopædia Britannica/Well")". - [Sustainable Groundwater Development theme of the Rural Water Supply Network (RWSN)](http://www.rural-water-supply.net/en/sustainable-groundwater-management) - [Water Portal – Akvopedia](http://akvopedia.org/wiki/Water_Portal) [Archived](https://web.archive.org/web/20141018231204/http://akvopedia.org/wiki/Water_Portal) 2014-10-18 at the [Wayback Machine](https://en.wikipedia.org/wiki/Wayback_Machine "Wayback Machine") - [Sustainable Sanitation and Water Management Toolbox](http://www.sswm.info/) - [U.S. Centers for Disease Control and Prevention (CDC) Healthy Water – Water Wells](https://www.cdc.gov/healthywater/drinking/private/wells/index.html) Site covering well basics, guidelines for proper siting and location of wells to avoid contamination, well testing, diseases related to wells, emergency well treatment and other topics. - [US Geological Survey – Ground water: Wells](https://ga.water.usgs.gov/edu/earthgwwells.html) - [US Geological Survey – Water Science Pictures Flowing Artesian Well](https://ga.water.usgs.gov/edu/gwartesian.html) - [Drilling wells 18 extremely useful questions and answers](https://www.euforaje.ro/foraje-puturi/) - [American Ground Water Trust](http://agwt.org/) - [Lifewater International Technical Library](http://www.lifewater.org/resources/ground_water.html#GW) [Archived](https://web.archive.org/web/20130616030412/http://www.lifewater.org/resources/ground_water.html#GW) 2013-06-16 at the [Wayback Machine](https://en.wikipedia.org/wiki/Wayback_Machine "Wayback Machine") - [Well Construction Technical Resources for NGOs](http://www.watersanitationhygiene.org/References/Technical%20Resources%20-%20Wells.htm) \| [v](https://en.wikipedia.org/wiki/Template:Geotechnical_engineering "Template:Geotechnical engineering") [t](https://en.wikipedia.org/wiki/Template_talk:Geotechnical_engineering "Template talk:Geotechnical engineering") [e](https://en.wikipedia.org/wiki/Special:EditPage/Template:Geotechnical_engineering "Special:EditPage/Template:Geotechnical engineering")[Geotechnical engineering](https://en.wikipedia.org/wiki/Geotechnical_engineering "Geotechnical engineering") \| \| \|---\|---\| \| [Offshore geotechnical engineering](https://en.wikipedia.org/wiki/Offshore_geotechnical_engineering "Offshore geotechnical engineering") \| \| \| [Investigation](https://en.wikipedia.org/wiki/Geotechnical_investigation "Geotechnical investigation") and instrumentation \| \| \| \| \| \| Field (in situ) \| [![](https://upload.wikimedia.org/wikipedia/commons/thumb/5/5e/Core_sample.svg/20px-Core_sample.svg.png)](https://en.wikipedia.org/wiki/File:Core_sample.svg) [Core drill](https://en.wikipedia.org/wiki/Core_drill "Core drill") [![](https://upload.wikimedia.org/wikipedia/commons/thumb/2/28/Cone_penetration_test.svg/20px-Cone_penetration_test.svg.png)](https://en.wikipedia.org/wiki/File:Cone_penetration_test.svg) [Cone penetration test](https://en.wikipedia.org/wiki/Cone_penetration_test "Cone penetration test") [![](https://upload.wikimedia.org/wikipedia/commons/thumb/1/10/Geo-electrical_sounding.svg/20px-Geo-electrical_sounding.svg.png)](https://en.wikipedia.org/wiki/File:Geo-electrical_sounding.svg) [Geo-electrical sounding](https://en.wikipedia.org/w/index.php?title=Geo-electrical_sounding&action=edit&redlink=1 "Geo-electrical sounding (page does not exist)") [![](https://upload.wikimedia.org/wikipedia/commons/thumb/7/7b/In_situ_permeameter_test.svg/20px-In_situ_permeameter_test.svg.png)](https://en.wikipedia.org/wiki/File:In_situ_permeameter_test.svg) [Permeability test](https://en.wikipedia.org/wiki/Permeability_\(Earth_sciences\) "Permeability (Earth sciences)") [![](https://upload.wikimedia.org/wikipedia/commons/thumb/a/a2/Load_test.svg/20px-Load_test.svg.png)](https://en.wikipedia.org/wiki/File:Load_test.svg) [Load test](https://en.wikipedia.org/wiki/Load_test "Load test") [Static](https://en.wikipedia.org/wiki/Static_load_testing "Static load testing") [Dynamic](https://en.wikipedia.org/wiki/Dynamic_load_testing "Dynamic load testing") [Statnamic](https://en.wikipedia.org/wiki/Statnamic_load_test "Statnamic load test") [![](https://upload.wikimedia.org/wikipedia/commons/thumb/f/fe/Pore_pressure_measurement.svg/20px-Pore_pressure_measurement.svg.png)](https://en.wikipedia.org/wiki/File:Pore_pressure_measurement.svg) Pore pressure measurement [Piezometer](https://en.wikipedia.org/wiki/Piezometer "Piezometer") [Well](https://en.wikipedia.org/wiki/Well#Classification) [![](https://upload.wikimedia.org/wikipedia/commons/thumb/5/5d/Ram_sounding.svg/20px-Ram_sounding.svg.png)](https://en.wikipedia.org/wiki/File:Ram_sounding.svg) [Ram sounding](https://en.wikipedia.org/w/index.php?title=Ram_sounding&action=edit&redlink=1 "Ram sounding (page does not exist)") [![](https://upload.wikimedia.org/wikipedia/commons/thumb/e/e4/Rock_control_drilling.svg/20px-Rock_control_drilling.svg.png)](https://en.wikipedia.org/wiki/File:Rock_control_drilling.svg) [Rock control drilling](https://en.wikipedia.org/w/index.php?title=Rock_control_drilling&action=edit&redlink=1 "Rock control drilling (page does not exist)") [![](https://upload.wikimedia.org/wikipedia/commons/thumb/8/81/Rotary_pressure_sounding.svg/20px-Rotary_pressure_sounding.svg.png)](https://en.wikipedia.org/wiki/File:Rotary_pressure_sounding.svg) [Rotary-pressure sounding](https://en.wikipedia.org/wiki/Rotary-pressure_sounding "Rotary-pressure sounding") [![](https://upload.wikimedia.org/wikipedia/commons/thumb/f/f9/Rotary_weight_sounding.svg/20px-Rotary_weight_sounding.svg.png)](https://en.wikipedia.org/wiki/File:Rotary_weight_sounding.svg) [Rotary weight sounding](https://en.wikipedia.org/w/index.php?title=Rotary_weight_sounding&action=edit&redlink=1 "Rotary weight sounding (page does not exist)") [![](https://upload.wikimedia.org/wikipedia/commons/thumb/0/05/Sample_series.svg/20px-Sample_series.svg.png)](https://en.wikipedia.org/wiki/File:Sample_series.svg) [Sample series](https://en.wikipedia.org/wiki/Soil_test#Soil_testing "Soil test") [![](https://upload.wikimedia.org/wikipedia/commons/thumb/7/75/Screw_plate_test.svg/20px-Screw_plate_test.svg.png)](https://en.wikipedia.org/wiki/File:Screw_plate_test.svg) [Screw plate test](https://en.wikipedia.org/w/index.php?title=Screw_plate_test&action=edit&redlink=1 "Screw plate test (page does not exist)") [Deformation monitoring](https://en.wikipedia.org/wiki/Deformation_monitoring "Deformation monitoring") [![](https://upload.wikimedia.org/wikipedia/commons/thumb/c/c6/Inclinometer.svg/20px-Inclinometer.svg.png)](https://en.wikipedia.org/wiki/File:Inclinometer.svg) [Inclinometer](https://en.wikipedia.org/wiki/Inclinometer "Inclinometer") [![](https://upload.wikimedia.org/wikipedia/commons/thumb/3/35/Settlement_recordings.svg/20px-Settlement_recordings.svg.png)](https://en.wikipedia.org/wiki/File:Settlement_recordings.svg) [Settlement recordings](https://en.wikipedia.org/wiki/Soil_consolidation "Soil consolidation") [![](https://upload.wikimedia.org/wikipedia/commons/thumb/a/ae/Shear_vane_test.svg/20px-Shear_vane_test.svg.png)](https://en.wikipedia.org/wiki/File:Shear_vane_test.svg) [Shear vane test](https://en.wikipedia.org/wiki/Shear_vane_test "Shear vane test") [![](https://upload.wikimedia.org/wikipedia/commons/thumb/d/d4/Simple_sounding.svg/20px-Simple_sounding.svg.png)](https://en.wikipedia.org/wiki/File:Simple_sounding.svg) [Simple sounding](https://en.wikipedia.org/w/index.php?title=Simple_sounding&action=edit&redlink=1 "Simple sounding (page does not exist)") [![](https://upload.wikimedia.org/wikipedia/commons/thumb/0/0d/Standard_penetration_test.svg/20px-Standard_penetration_test.svg.png)](https://en.wikipedia.org/wiki/File:Standard_penetration_test.svg) [Standard penetration test](https://en.wikipedia.org/wiki/Standard_penetration_test "Standard penetration test") [![](https://upload.wikimedia.org/wikipedia/commons/thumb/6/60/Total_sounding.svg/20px-Total_sounding.svg.png)](https://en.wikipedia.org/wiki/File:Total_sounding.svg) [Total sounding](https://en.wikipedia.org/wiki/Total_sounding "Total sounding") [![](https://upload.wikimedia.org/wikipedia/commons/thumb/7/71/Trial_pit.svg/20px-Trial_pit.svg.png)](https://en.wikipedia.org/wiki/File:Trial_pit.svg) [Trial pit](https://en.wikipedia.org/wiki/Trial_pit "Trial pit") [![](https://upload.wikimedia.org/wikipedia/commons/thumb/1/14/Visible_rock.svg/20px-Visible_rock.svg.png)](https://en.wikipedia.org/wiki/File:Visible_rock.svg) [Visible bedrock](https://en.wikipedia.org/wiki/Bedrock "Bedrock") [Nuclear densometer test](https://en.wikipedia.org/wiki/Nuclear_densometer "Nuclear densometer") [Exploration geophysics](https://en.wikipedia.org/wiki/Exploration_geophysics "Exploration geophysics") [Crosshole sonic logging](https://en.wikipedia.org/wiki/Crosshole_sonic_logging "Crosshole sonic logging") [Pile integrity test](https://en.wikipedia.org/wiki/Pile_integrity_test "Pile integrity test") [Wave equation analysis](https://en.wikipedia.org/wiki/Wave_equation_analysis "Wave equation analysis") \| \| [Laboratory testing](https://en.wikipedia.org/wiki/Soil_test "Soil test") \| [Soil classification](https://en.wikipedia.org/wiki/Soil_classification "Soil classification") [Atterberg limits](https://en.wikipedia.org/wiki/Atterberg_limits "Atterberg limits") [California bearing ratio](https://en.wikipedia.org/wiki/California_bearing_ratio "California bearing ratio") [Direct shear test](https://en.wikipedia.org/wiki/Direct_shear_test "Direct shear test") [Hydrometer](https://en.wikipedia.org/wiki/Hydrometer "Hydrometer") [Proctor compaction test](https://en.wikipedia.org/wiki/Proctor_compaction_test "Proctor compaction test") [R-value](https://en.wikipedia.org/wiki/R-value_\(soils\) "R-value (soils)") [Sieve analysis](https://en.wikipedia.org/wiki/Sieve_analysis "Sieve analysis") [Triaxial shear test](https://en.wikipedia.org/wiki/Triaxial_shear_test "Triaxial shear test") [Oedometer test](https://en.wikipedia.org/wiki/Oedometer_test "Oedometer test") [Hydraulic conductivity tests](https://en.wikipedia.org/wiki/Hydraulic_conductivity#Experimental_approach "Hydraulic conductivity") [Water content tests](https://en.wikipedia.org/wiki/Water_content#Measurement "Water content") \| \| [Soil](https://en.wikipedia.org/wiki/Soil "Soil") \| \| \| \| \| \| Types \| [Clay](https://en.wikipedia.org/wiki/Clay "Clay") [Silt](https://en.wikipedia.org/wiki/Silt "Silt") [Sand](https://en.wikipedia.org/wiki/Sand "Sand") [Gravel](https://en.wikipedia.org/wiki/Gravel "Gravel") [Peat](https://en.wikipedia.org/wiki/Peat "Peat") [Loam](https://en.wikipedia.org/wiki/Loam "Loam") [Loess](https://en.wikipedia.org/wiki/Loess "Loess") \| \| Properties \| [Hydraulic conductivity](https://en.wikipedia.org/wiki/Hydraulic_conductivity "Hydraulic conductivity") [Water content](https://en.wikipedia.org/wiki/Water_content "Water content") [Void ratio](https://en.wikipedia.org/wiki/Void_ratio "Void ratio") [Bulk density](https://en.wikipedia.org/wiki/Bulk_density "Bulk density") [Thixotropy](https://en.wikipedia.org/wiki/Thixotropy "Thixotropy") [Reynolds' dilatancy](https://en.wikipedia.org/wiki/Reynolds%27_dilatancy "Reynolds' dilatancy") [Angle of repose](https://en.wikipedia.org/wiki/Angle_of_repose "Angle of repose") [Friction angle](https://en.wikipedia.org/wiki/Friction#Angle_of_friction "Friction") [Cohesion](https://en.wikipedia.org/wiki/Cohesion_\(geology\) "Cohesion (geology)") [Porosity](https://en.wikipedia.org/wiki/Porosity "Porosity") [Permeability](https://en.wikipedia.org/wiki/Permeability_\(earth_sciences\) "Permeability (earth sciences)") [Specific storage](https://en.wikipedia.org/wiki/Specific_storage "Specific storage") [Shear strength](https://en.wikipedia.org/wiki/Shear_strength_\(soil\) "Shear strength (soil)") [Sensitivity](https://en.wikipedia.org/wiki/Soil_liquefaction "Soil liquefaction") \| \| Structures ([Interaction](https://en.wikipedia.org/wiki/Soil-structure_interaction "Soil-structure interaction")) \| \| \| \| \| \| Natural features \| [Topography](https://en.wikipedia.org/wiki/Topography "Topography") [Vegetation](https://en.wikipedia.org/wiki/Vegetation "Vegetation") [Terrain](https://en.wikipedia.org/wiki/Terrain "Terrain") [Topsoil](https://en.wikipedia.org/wiki/Topsoil "Topsoil") [Water table](https://en.wikipedia.org/wiki/Water_table "Water table") [Bedrock](https://en.wikipedia.org/wiki/Bedrock "Bedrock") [Subgrade](https://en.wikipedia.org/wiki/Subgrade "Subgrade") [Subsoil](https://en.wikipedia.org/wiki/Subsoil "Subsoil") \| \| [Earthworks](https://en.wikipedia.org/wiki/Earthworks_\(engineering\) "Earthworks (engineering)") \| Shoring structures [Retaining walls](https://en.wikipedia.org/wiki/Retaining_wall "Retaining wall") [Gabion](https://en.wikipedia.org/wiki/Gabion "Gabion") [Ground freezing](https://en.wikipedia.org/wiki/Ground_freezing "Ground freezing") [Mechanically stabilized earth](https://en.wikipedia.org/wiki/Mechanically_stabilized_earth "Mechanically stabilized earth") [Pressure grouting](https://en.wikipedia.org/wiki/Pressure_grouting "Pressure grouting") [Slurry wall](https://en.wikipedia.org/wiki/Slurry_wall "Slurry wall") [Soil nailing](https://en.wikipedia.org/wiki/Soil_nailing "Soil nailing") [Tieback](https://en.wikipedia.org/wiki/Tieback_\(geotechnical\) "Tieback (geotechnical)") [Land development](https://en.wikipedia.org/wiki/Land_development "Land development") [Landfill](https://en.wikipedia.org/wiki/Landfill "Landfill") [Excavation](https://en.wikipedia.org/wiki/Digging "Digging") [Trench](https://en.wikipedia.org/wiki/Trench "Trench") [Embankment](https://en.wikipedia.org/wiki/Embankment_\(earthworks\) "Embankment (earthworks)") [Cut](https://en.wikipedia.org/wiki/Cut_\(earthworks\) "Cut (earthworks)") [Causeway](https://en.wikipedia.org/wiki/Causeway "Causeway") [Terracing](https://en.wikipedia.org/wiki/Terrace_\(earthworks\) "Terrace (earthworks)") [Cut-and-cover](https://en.wikipedia.org/wiki/Tunnel#Cut-and-cover "Tunnel") [Cut and fill](https://en.wikipedia.org/wiki/Cut_and_fill "Cut and fill") [Fill dirt](https://en.wikipedia.org/wiki/Fill_dirt "Fill dirt") [Grading](https://en.wikipedia.org/wiki/Grading_\(engineering\) "Grading (engineering)") [Land reclamation](https://en.wikipedia.org/wiki/Land_reclamation "Land reclamation") [Track bed](https://en.wikipedia.org/wiki/Track_bed "Track bed") [Erosion control](https://en.wikipedia.org/wiki/Erosion_control "Erosion control") [Earth structure](https://en.wikipedia.org/wiki/Earth_structure "Earth structure") [Expanded clay aggregate](https://en.wikipedia.org/wiki/Expanded_clay_aggregate "Expanded clay aggregate") [Crushed stone](https://en.wikipedia.org/wiki/Crushed_stone "Crushed stone") [Geosynthetics](https://en.wikipedia.org/wiki/Geosynthetics "Geosynthetics") [Geotextile](https://en.wikipedia.org/wiki/Geotextile "Geotextile") [Geomembrane](https://en.wikipedia.org/wiki/Geomembrane "Geomembrane") [Geosynthetic clay liner](https://en.wikipedia.org/wiki/Geosynthetic_clay_liner "Geosynthetic clay liner") [Cellular confinement](https://en.wikipedia.org/wiki/Cellular_confinement "Cellular confinement") [Infiltration](https://en.wikipedia.org/wiki/Infiltration_\(hydrology\) "Infiltration (hydrology)") \| \| [Foundations](https://en.wikipedia.org/wiki/Foundation_\(engineering\) "Foundation (engineering)") \| [Shallow](https://en.wikipedia.org/wiki/Shallow_foundation "Shallow foundation") [Deep](https://en.wikipedia.org/wiki/Deep_foundation "Deep foundation") \| \| [Mechanics](https://en.wikipedia.org/wiki/Soil_mechanics "Soil mechanics") \| \| \| \| \| \| Forces \| [Effective stress](https://en.wikipedia.org/wiki/Effective_stress "Effective stress") [Pore water pressure](https://en.wikipedia.org/wiki/Pore_water_pressure "Pore water pressure") [Lateral earth pressure](https://en.wikipedia.org/wiki/Lateral_earth_pressure "Lateral earth pressure") [Overburden pressure](https://en.wikipedia.org/wiki/Overburden_pressure "Overburden pressure") [Preconsolidation pressure](https://en.wikipedia.org/wiki/Preconsolidation_pressure "Preconsolidation pressure") \| \| Phenomena and problems \| [Permafrost](https://en.wikipedia.org/wiki/Permafrost "Permafrost") [Frost heaving](https://en.wikipedia.org/wiki/Frost_heaving "Frost heaving") [Consolidation](https://en.wikipedia.org/wiki/Consolidation_\(soil\) "Consolidation (soil)") [Compaction](https://en.wikipedia.org/wiki/Soil_compaction "Soil compaction") [Earthquake](https://en.wikipedia.org/wiki/Earthquake "Earthquake") [Response spectrum](https://en.wikipedia.org/wiki/Response_spectrum "Response spectrum") [Seismic hazard](https://en.wikipedia.org/wiki/Seismic_hazard "Seismic hazard") [Shear wave](https://en.wikipedia.org/wiki/S_wave "S wave") [Landslide](https://en.wikipedia.org/wiki/Landslide "Landslide") analysis [Stability analysis](https://en.wikipedia.org/wiki/Slope_stability_analysis "Slope stability analysis") [Mitigation](https://en.wikipedia.org/wiki/Landslide_mitigation "Landslide mitigation") [Classification](https://en.wikipedia.org/wiki/Landslide_classification "Landslide classification") [Sliding criterion](https://en.wikipedia.org/wiki/Sliding_criterion_\(geotechnical_engineering\) "Sliding criterion (geotechnical engineering)") [Slab stabilisation](https://en.wikipedia.org/wiki/Road#Slab_stabilization "Road") [Bearing capacity](https://en.wikipedia.org/wiki/Bearing_capacity "Bearing capacity") [Stress distribution in soil](https://en.wikipedia.org/wiki/Stress_distribution_in_soil "Stress distribution in soil") \| \| [Numerical analysis software](https://en.wikipedia.org/wiki/Software "Software") \| [SEEP2D](https://en.wikipedia.org/wiki/SEEP2D "SEEP2D") [STABL](https://en.wikipedia.org/w/index.php?title=STABL&action=edit&redlink=1 "STABL (page does not exist)") [SVFlux](https://en.wikipedia.org/wiki/SVFlux "SVFlux") [SVSlope](https://en.wikipedia.org/wiki/SVSlope "SVSlope") [UTEXAS](https://en.wikipedia.org/wiki/UTEXAS "UTEXAS") [Plaxis](https://en.wikipedia.org/wiki/Plaxis "Plaxis") \| \| [Related fields](https://en.wikipedia.org/wiki/Geoprofessions "Geoprofessions") \| [Geology](https://en.wikipedia.org/wiki/Geology "Geology") [Geochemistry](https://en.wikipedia.org/wiki/Geochemistry "Geochemistry") [Petrology](https://en.wikipedia.org/wiki/Petrology "Petrology") [Earthquake engineering](https://en.wikipedia.org/wiki/Earthquake_engineering "Earthquake engineering") [Geomorphology](https://en.wikipedia.org/wiki/Geomorphology "Geomorphology") [Soil science](https://en.wikipedia.org/wiki/Soil_science "Soil science") [Hydrology](https://en.wikipedia.org/wiki/Hydrology "Hydrology") [Hydrogeology](https://en.wikipedia.org/wiki/Hydrogeology "Hydrogeology") [Biogeography](https://en.wikipedia.org/wiki/Biogeography "Biogeography") [Earth materials](https://en.wikipedia.org/wiki/Earth_materials "Earth materials") [Archaeology](https://en.wikipedia.org/wiki/Archaeology "Archaeology") [Agricultural science](https://en.wikipedia.org/wiki/Agricultural_science "Agricultural science") [Agrology](https://en.wikipedia.org/wiki/Agrology "Agrology") \| \| [v](https://en.wikipedia.org/wiki/Template:Man-made_and_man-related_subterranea "Template:Man-made and man-related subterranea") [t](https://en.wikipedia.org/wiki/Template_talk:Man-made_and_man-related_subterranea "Template talk:Man-made and man-related subterranea") [e](https://en.wikipedia.org/wiki/Special:EditPage/Template:Man-made_and_man-related_subterranea "Special:EditPage/Template:Man-made and man-related subterranea")Man-made and man-related [subterranea](https://en.wikipedia.org/wiki/Subterranea_\(geography\) "Subterranea (geography)") \| \| \|---\|---\| \| Natural features \| [Cave](https://en.wikipedia.org/wiki/Cave "Cave") [Cenote](https://en.wikipedia.org/wiki/Cenote "Cenote") [Grotto](https://en.wikipedia.org/wiki/Grotto "Grotto") [Sinkhole](https://en.wikipedia.org/wiki/Sinkhole "Sinkhole") \| \| Civilian features \| [Bank vault](https://en.wikipedia.org/wiki/Bank_vault "Bank vault") [Basement](https://en.wikipedia.org/wiki/Basement "Basement") [Burial vault (tomb)](https://en.wikipedia.org/wiki/Burial_vault_\(tomb\) "Burial vault (tomb)") [Borehole](https://en.wikipedia.org/wiki/Borehole "Borehole") [Catacombs](https://en.wikipedia.org/wiki/Catacombs "Catacombs") [Dungeon](https://en.wikipedia.org/wiki/Dungeon "Dungeon") [Dugout (shelter)](https://en.wikipedia.org/wiki/Dugout_\(shelter\) "Dugout (shelter)") [Dry well](https://en.wikipedia.org/wiki/Dry_well "Dry well") [Earth shelter](https://en.wikipedia.org/wiki/Earth_shelter "Earth shelter") [Erdstall](https://en.wikipedia.org/wiki/Erdstall "Erdstall") [Fogou](https://en.wikipedia.org/wiki/Fogou "Fogou") [Hypogeum](https://en.wikipedia.org/wiki/Hypogeum "Hypogeum") [Manhole](https://en.wikipedia.org/wiki/Manhole "Manhole") [Rapid transit](https://en.wikipedia.org/wiki/Rapid_transit "Rapid transit") [Rock-cut tomb](https://en.wikipedia.org/wiki/Rock-cut_tomb "Rock-cut tomb") [Root cellar](https://en.wikipedia.org/wiki/Root_cellar "Root cellar") [Tunnel](https://en.wikipedia.org/wiki/Tunnel "Tunnel") [Utility vault](https://en.wikipedia.org/wiki/Utility_vault "Utility vault") [Underground city](https://en.wikipedia.org/wiki/Underground_city "Underground city") [Well]() [Wine cave](https://en.wikipedia.org/wiki/Wine_cave "Wine cave") [Secret passage](https://en.wikipedia.org/wiki/Secret_passage "Secret passage") [Semi-basement](https://en.wikipedia.org/wiki/Semi-basement "Semi-basement") [Stepwell](https://en.wikipedia.org/wiki/Stepwell "Stepwell") [Storm cellar](https://en.wikipedia.org/wiki/Storm_cellar "Storm cellar") [Smuggling tunnel](https://en.wikipedia.org/wiki/Smuggling_tunnel "Smuggling tunnel") [Ventilation shaft](https://en.wikipedia.org/wiki/Ventilation_shaft "Ventilation shaft") \| \| Military features \| [Air raid shelter](https://en.wikipedia.org/wiki/Air_raid_shelter "Air raid shelter") [Bunker](https://en.wikipedia.org/wiki/Bunker "Bunker") [Blast shelter](https://en.wikipedia.org/wiki/Blast_shelter "Blast shelter") [Casemate](https://en.wikipedia.org/wiki/Casemate "Casemate") [Fallout shelter](https://en.wikipedia.org/wiki/Fallout_shelter "Fallout shelter") [Missile launch facility](https://en.wikipedia.org/wiki/Missile_launch_facility "Missile launch facility") (silo) [Scallywag bunker](https://en.wikipedia.org/wiki/Scallywag_bunker "Scallywag bunker") [Underground base](https://en.wikipedia.org/wiki/Underground_base "Underground base") [Underground hangar](https://en.wikipedia.org/wiki/Underground_hangar "Underground hangar") [Spider hole](https://en.wikipedia.org/wiki/Spider_hole "Spider hole") \| \| [Mining](https://en.wikipedia.org/wiki/Mining "Mining"), [quarrying](https://en.wikipedia.org/wiki/Quarry "Quarry"), and [underground construction](https://en.wikipedia.org/wiki/Underground_construction "Underground construction") \| [Rock-cut architecture](https://en.wikipedia.org/wiki/Rock-cut_architecture "Rock-cut architecture") [Subsurface utility engineering](https://en.wikipedia.org/wiki/Subsurface_utility_engineering "Subsurface utility engineering") [Tunnel construction](https://en.wikipedia.org/wiki/Tunnel_construction "Tunnel construction") [Underground mine ventilation](https://en.wikipedia.org/wiki/Underground_mine_ventilation "Underground mine ventilation") [Underground hard-rock mining](https://en.wikipedia.org/wiki/Underground_hard-rock_mining "Underground hard-rock mining") [Underground soft-rock mining](https://en.wikipedia.org/wiki/Underground_soft-rock_mining "Underground soft-rock mining") \| \| Related topics \| [Cave dweller](https://en.wikipedia.org/wiki/Cave_dweller "Cave dweller") [Caves of Maastricht](https://en.wikipedia.org/wiki/Caves_of_Maastricht "Caves of Maastricht") [Civil defense](https://en.wikipedia.org/wiki/Civil_defense "Civil defense") [Coober Pedy](https://en.wikipedia.org/wiki/Coober_Pedy "Coober Pedy") [Houston tunnel system](https://en.wikipedia.org/wiki/Houston_tunnel_system "Houston tunnel system") [Kőbánya cellar system](https://en.wikipedia.org/wiki/K%C5%91b%C3%A1nya_cellar_system "Kőbánya cellar system") [Tunnel warfare](https://en.wikipedia.org/wiki/Tunnel_warfare "Tunnel warfare") [Tunnel network](https://en.wikipedia.org/wiki/Tunnel_network "Tunnel network") [Trench warfare](https://en.wikipedia.org/wiki/Trench_warfare "Trench warfare") [Underground living](https://en.wikipedia.org/wiki/Underground_living "Underground living") [Underground City (Beijing)](https://en.wikipedia.org/wiki/Underground_City_\(Beijing\) "Underground City (Beijing)") [Underground City, Montreal](https://en.wikipedia.org/wiki/Underground_City,_Montreal "Underground City, Montreal") [Mine exploration](https://en.wikipedia.org/wiki/Mine_exploration "Mine exploration") [Mines of Paris](https://en.wikipedia.org/wiki/Mines_of_Paris "Mines of Paris") [Mole people](https://en.wikipedia.org/wiki/Mole_people "Mole people") [Naples underground geothermal zone](https://en.wikipedia.org/wiki/Naples_underground_geothermal_zone "Naples underground geothermal zone") [Sapping](https://en.wikipedia.org/wiki/Sapping "Sapping") [Subterranean London](https://en.wikipedia.org/wiki/Subterranean_London "Subterranean London") [Subterranean Toledo](https://en.wikipedia.org/wiki/Subterranean_Toledo "Subterranean Toledo") [Subterranean warfare](https://en.wikipedia.org/wiki/Subterranean_warfare "Subterranean warfare") [Subterranean fiction](https://en.wikipedia.org/wiki/Subterranean_fiction "Subterranean fiction") \| \| Earth shelters US \| [Bill Gates' house](https://en.wikipedia.org/wiki/Bill_Gates%27_house "Bill Gates' house") [Forestiere Underground Gardens](https://en.wikipedia.org/wiki/Forestiere_Underground_Gardens "Forestiere Underground Gardens") [Underground House Colorado](https://en.wikipedia.org/wiki/Underground_House_Colorado "Underground House Colorado") [Underground House Las Vegas](https://en.wikipedia.org/wiki/Underground_House_Las_Vegas "Underground House Las Vegas") [Underground World Home](https://en.wikipedia.org/wiki/Underground_World_Home "Underground World Home") \| \| Earth shelters UK \| [Underhill, Holme](https://en.wikipedia.org/wiki/Underhill,_Holme "Underhill, Holme") [Hockerton Housing Project](https://en.wikipedia.org/wiki/Hockerton_Housing_Project "Hockerton Housing Project") [Malator](https://en.wikipedia.org/wiki/Malator "Malator") \| \| Earth shelters Australia \| [Coober Pedy](https://en.wikipedia.org/wiki/Coober_Pedy "Coober Pedy") [Lightning Ridge](https://en.wikipedia.org/wiki/Lightning_Ridge,_New_South_Wales "Lightning Ridge, New South Wales") \| \| [Authority control databases](https://en.wikipedia.org/wiki/Help:Authority_control "Help:Authority control") [![Edit this at Wikidata](https://upload.wikimedia.org/wikipedia/en/thumb/8/8a/OOjs_UI_icon_edit-ltr-progressive.svg/20px-OOjs_UI_icon_edit-ltr-progressive.svg.png)](https://www.wikidata.org/wiki/Q43483#identifiers "Edit this at Wikidata") \| \| \|---\|---\| \| International \| [GND](https://d-nb.info/gnd/4008491-7) \| \| National \| [United States](https://id.loc.gov/authorities/sh85146057) [France](https://catalogue.bnf.fr/ark:/12148/cb119759000) [BnF data](https://data.bnf.fr/ark:/12148/cb119759000) [Japan](https://id.ndl.go.jp/auth/ndlna/00563888) [Czech Republic](https://aleph.nkp.cz/F/?func=find-c&local_base=aut&ccl_term=ica=ph116306&CON_LNG=ENG) [Spain](https://datos.bne.es/resource/XX524606) [Latvia](https://kopkatalogs.lv/F?func=direct&local_base=lnc10&doc_number=000082718&P_CON_LNG=ENG) [Poland](https://dbn.bn.org.pl/descriptor-details/9810545826905606) [Israel](https://www.nli.org.il/en/authorities/987007553637505171) \| \| Other \| [Yale LUX](https://lux.collections.yale.edu/view/concept/9c201eec-4906-497e-8c9a-3749b416d797) \| ![](https://en.wikipedia.org/wiki/Special:CentralAutoLogin/start?useformat=desktop&type=1x1&usesul3=1) Retrieved from "<https://en.wikipedia.org/w/index.php?title=Well&oldid=1348155091>" [Categories](https://en.wikipedia.org/wiki/Help:Category "Help:Category"): - [Water wells](https://en.wikipedia.org/wiki/Category:Water_wells "Category:Water wells") - [Archaeological features](https://en.wikipedia.org/wiki/Category:Archaeological_features "Category:Archaeological features") - [Bodies of water](https://en.wikipedia.org/wiki/Category:Bodies_of_water "Category:Bodies of water") - [Water supply infrastructure](https://en.wikipedia.org/wiki/Category:Water_supply_infrastructure "Category:Water supply infrastructure") - [In situ geotechnical investigations](https://en.wikipedia.org/wiki/Category:In_situ_geotechnical_investigations "Category:In situ geotechnical investigations") Hidden categories: - [All articles with dead external links](https://en.wikipedia.org/wiki/Category:All_articles_with_dead_external_links "Category:All articles with dead external links") - [Articles with dead external links from August 2025](https://en.wikipedia.org/wiki/Category:Articles_with_dead_external_links_from_August_2025 "Category:Articles with dead external links from August 2025") - [Articles with permanently dead external links](https://en.wikipedia.org/wiki/Category:Articles_with_permanently_dead_external_links "Category:Articles with permanently dead external links") - [Articles with short description](https://en.wikipedia.org/wiki/Category:Articles_with_short_description "Category:Articles with short description") - [Short description is different from Wikidata](https://en.wikipedia.org/wiki/Category:Short_description_is_different_from_Wikidata "Category:Short description is different from Wikidata") - [All articles with unsourced statements](https://en.wikipedia.org/wiki/Category:All_articles_with_unsourced_statements "Category:All articles with unsourced statements") - [Articles with unsourced statements from April 2021](https://en.wikipedia.org/wiki/Category:Articles_with_unsourced_statements_from_April_2021 "Category:Articles with unsourced statements from April 2021") - [Articles with unsourced statements from February 2013](https://en.wikipedia.org/wiki/Category:Articles_with_unsourced_statements_from_February_2013 "Category:Articles with unsourced statements from February 2013") - [Articles with unsourced statements from May 2016](https://en.wikipedia.org/wiki/Category:Articles_with_unsourced_statements_from_May_2016 "Category:Articles with unsourced statements from May 2016") - [Articles with unsourced statements from January 2016](https://en.wikipedia.org/wiki/Category:Articles_with_unsourced_statements_from_January_2016 "Category:Articles with unsourced statements from January 2016") - [All articles with vague or ambiguous time](https://en.wikipedia.org/wiki/Category:All_articles_with_vague_or_ambiguous_time "Category:All articles with vague or ambiguous time") - [Vague or ambiguous time from May 2016](https://en.wikipedia.org/wiki/Category:Vague_or_ambiguous_time_from_May_2016 "Category:Vague or ambiguous time from May 2016") - [Wikipedia articles needing clarification from May 2021](https://en.wikipedia.org/wiki/Category:Wikipedia_articles_needing_clarification_from_May_2021 "Category:Wikipedia articles needing clarification from May 2021") - [Commons category link is on Wikidata](https://en.wikipedia.org/wiki/Category:Commons_category_link_is_on_Wikidata "Category:Commons category link is on Wikidata") - [Webarchive template wayback links](https://en.wikipedia.org/wiki/Category:Webarchive_template_wayback_links "Category:Webarchive template wayback links") - This page was last edited on 11 April 2026, at 01:17 (UTC). - Text is available under the [Creative Commons Attribution-ShareAlike 4.0 License](https://en.wikipedia.org/wiki/Wikipedia:Text_of_the_Creative_Commons_Attribution-ShareAlike_4.0_International_License "Wikipedia:Text of the Creative Commons Attribution-ShareAlike 4.0 International License"); additional terms may apply. By using this site, you agree to the [Terms of Use](https://foundation.wikimedia.org/wiki/Special:MyLanguage/Policy:Terms_of_Use "foundation:Special:MyLanguage/Policy:Terms of Use") and [Privacy Policy](https://foundation.wikimedia.org/wiki/Special:MyLanguage/Policy:Privacy_policy "foundation:Special:MyLanguage/Policy:Privacy policy"). Wikipedia® is a registered trademark of the [Wikimedia Foundation, Inc.](https://wikimediafoundation.org/), a non-profit organization. - [Privacy policy](https://foundation.wikimedia.org/wiki/Special:MyLanguage/Policy:Privacy_policy) - [About Wikipedia](https://en.wikipedia.org/wiki/Wikipedia:About) - [Disclaimers](https://en.wikipedia.org/wiki/Wikipedia:General_disclaimer) - [Contact Wikipedia](https://en.wikipedia.org/wiki/Wikipedia:Contact_us) - [Legal & safety contacts](https://foundation.wikimedia.org/wiki/Special:MyLanguage/Legal:Wikimedia_Foundation_Legal_and_Safety_Contact_Information) - [Code of Conduct](https://foundation.wikimedia.org/wiki/Special:MyLanguage/Policy:Universal_Code_of_Conduct) - [Developers](https://developer.wikimedia.org/) - [Statistics](https://stats.wikimedia.org/#/en.wikipedia.org) - [Cookie statement](https://foundation.wikimedia.org/wiki/Special:MyLanguage/Policy:Cookie_statement) - [Mobile view](https://en.wikipedia.org/w/index.php?title=Well&mobileaction=toggle_view_mobile) - [![Wikimedia Foundation](https://en.wikipedia.org/static/images/footer/wikimedia.svg)](https://www.wikimedia.org/) - [![Powered by MediaWiki](https://en.wikipedia.org/w/resources/assets/mediawiki_compact.svg)](https://www.mediawiki.org/) Search Toggle the table of contents Well 123 languages [Add topic](https://en.wikipedia.org/wiki/Well)
Readable Markdown	"Village pump" redirects here. For the set of Wikipedia discussion pages, see [Wikipedia:Village pump](https://en.wikipedia.org/wiki/Wikipedia:Village_pump "Wikipedia:Village pump"). [![](https://upload.wikimedia.org/wikipedia/commons/thumb/0/01/Faryab-_village_dug_well.JPG/250px-Faryab-_village_dug_well.JPG)](https://en.wikipedia.org/wiki/File:Faryab-_village_dug_well.JPG) A dug well in a village in [Faryab Province](https://en.wikipedia.org/wiki/Faryab_Province "Faryab Province"), [Afghanistan](https://en.wikipedia.org/wiki/Afghanistan "Afghanistan") [![](https://upload.wikimedia.org/wikipedia/commons/thumb/0/02/Well-cistern.jpg/250px-Well-cistern.jpg)](https://en.wikipedia.org/wiki/File:Well-cistern.jpg) The difference between a well and a [cistern](https://en.wikipedia.org/wiki/Cistern "Cistern") is in the source of the water: a cistern collects [rainwater](https://en.wikipedia.org/wiki/Rainwater "Rainwater") whereas a well draws from [groundwater](https://en.wikipedia.org/wiki/Groundwater "Groundwater"). A well is an excavation or structure created on the earth by [digging](https://en.wikipedia.org/wiki/Digging "Digging"), driving, or [drilling](https://en.wikipedia.org/wiki/Drilling "Drilling") to access [liquid](https://en.wikipedia.org/wiki/Liquid "Liquid") resources, usually [water](https://en.wikipedia.org/wiki/Water "Water"). The oldest and most common kind of well is a water well, to access [groundwater](https://en.wikipedia.org/wiki/Groundwater "Groundwater") in underground [aquifers](https://en.wikipedia.org/wiki/Aquifer "Aquifer"). The well water is drawn up by a [pump](https://en.wikipedia.org/wiki/Pump "Pump"), or using containers, such as [buckets](https://en.wikipedia.org/wiki/Bucket "Bucket") that are raised mechanically or by hand. Water can also be [injected back into the aquifer](https://en.wikipedia.org/wiki/Aquifer_storage_and_recovery "Aquifer storage and recovery") through the well. Wells were first constructed at least eight thousand years ago and historically vary in construction from a sediment of a dry watercourse to the [qanats](https://en.wikipedia.org/wiki/Qanat "Qanat") of Iran, and the [stepwells](https://en.wikipedia.org/wiki/Stepwell "Stepwell") and [sakiehs](https://en.wikipedia.org/wiki/Sakia "Sakia") of India. Placing a lining in the well shaft helps create stability, and linings of wood or [wickerwork](https://en.wikipedia.org/wiki/Wicker "Wicker") date back at least as far as the [Iron Age](https://en.wikipedia.org/wiki/Iron_Age "Iron Age"). Wells have traditionally been sunk by hand digging, as is still the case in rural areas of the developing world. These wells are inexpensive and low-tech as they use mostly manual labour, and the structure can be lined with [brick](https://en.wikipedia.org/wiki/Brick "Brick") or stone as the excavation proceeds. A more modern method called [caissoning](https://en.wikipedia.org/wiki/Caisson_\(engineering\) "Caisson (engineering)") uses pre-cast reinforced concrete well rings that are lowered into the hole. Driven wells can be created in unconsolidated material with a well hole structure, which consists of a hardened drive point and a screen of perforated pipe, after which a pump is installed to collect the water. Deeper wells can be excavated by hand drilling methods or machine drilling, using a [bit](https://en.wikipedia.org/wiki/Drill_bit "Drill bit") in a [borehole](https://en.wikipedia.org/wiki/Borehole "Borehole"). Drilled wells are usually cased with a factory-made pipe composed of steel or plastic. Drilled wells can access water at much greater depths than dug wells. Two broad classes of well are shallow or unconfined wells completed within the uppermost saturated [aquifer](https://en.wikipedia.org/wiki/Aquifer "Aquifer") at that location, and deep or confined wells, sunk through an impermeable stratum into an aquifer beneath. A collector well can be constructed adjacent to a freshwater lake or stream with water percolating through the intervening material. The site of a well can be selected by a [hydrogeologist](https://en.wikipedia.org/wiki/Hydrogeology "Hydrogeology"), or groundwater surveyor. Water may be pumped or hand drawn. Impurities from the surface can easily reach shallow sources and contamination of the supply by pathogens or chemical contaminants needs to be avoided. Well water typically contains more minerals in solution than surface water and may require [treatment](https://en.wikipedia.org/wiki/Water_treatment "Water treatment") before being potable. [Soil salination](https://en.wikipedia.org/wiki/Soil_salinity "Soil salinity") can occur as the water table falls and the surrounding soil begins to dry out. Another environmental problem is the potential for [methane](https://en.wikipedia.org/wiki/Methane "Methane") to seep into the water. [![](https://upload.wikimedia.org/wikipedia/commons/thumb/7/7b/Tunis1960-150_hg.jpg/250px-Tunis1960-150_hg.jpg)](https://en.wikipedia.org/wiki/File:Tunis1960-150_hg.jpg) Camel drawing water from a well, [Djerba](https://en.wikipedia.org/wiki/Djerba "Djerba") island, Tunisia, 1960 Very early [Neolithic](https://en.wikipedia.org/wiki/Neolithic "Neolithic") wells are known from the [Eastern Mediterranean](https://en.wikipedia.org/wiki/Eastern_Mediterranean "Eastern Mediterranean").[\[1\]](https://en.wikipedia.org/wiki/Well#cite_note-1) The oldest reliably dated well is from the [pre-pottery neolithic](https://en.wikipedia.org/wiki/Prehistoric_Cyprus#Aceramic_Neolithic "Prehistoric Cyprus") (PPN) site of Kissonerga-Mylouthkia on [Cyprus](https://en.wikipedia.org/wiki/Cyprus "Cyprus"). At around 8400 BC a shaft (well 116) of circular diameter was driven through limestone to reach an [aquifer](https://en.wikipedia.org/wiki/Aquifer "Aquifer") at a depth of 8 metres (26 ft). Well 2070 from Kissonerga-Mylouthkia, dating to the late PPN, reaches a depth of 13 metres (43 ft). Other slightly younger wells are known from this site and from neighbouring Parekklisha-Shillourokambos. A first stone lined[\[2\]](https://en.wikipedia.org/wiki/Well#cite_note-2) well of 5.5 metres (18 ft) depth is documented from a drowned final PPN (c. 7000 BC) site at ['Atlit-Yam](https://en.wikipedia.org/wiki/Atlit_Yam "Atlit Yam") off the coast near modern [Haifa](https://en.wikipedia.org/wiki/Haifa "Haifa") in [Israel](https://en.wikipedia.org/wiki/Israel "Israel"). [![](https://upload.wikimedia.org/wikipedia/commons/thumb/7/74/K%C3%BCckhoven_%28Erkelenz%29%2C_Brunnenbaureste_um_5300_v._Ch._.jpg/120px-K%C3%BCckhoven_%28Erkelenz%29%2C_Brunnenbaureste_um_5300_v._Ch._.jpg)](https://en.wikipedia.org/wiki/File:K%C3%BCckhoven_\(Erkelenz\),_Brunnenbaureste_um_5300_v._Ch._.jpg) Neolithic [Linear Pottery culture](https://en.wikipedia.org/wiki/Linear_Pottery_culture "Linear Pottery culture") well, 5300 BC, [Erkelenz](https://en.wikipedia.org/wiki/Erkelenz "Erkelenz"), Germany Wood-lined wells are known from the early Neolithic [Linear Pottery culture](https://en.wikipedia.org/wiki/Linear_Pottery_culture "Linear Pottery culture"), for example in Ostrov, Czech Republic, dated 5265 BC,[\[3\]](https://en.wikipedia.org/wiki/Well#cite_note-3) Kückhoven (an outlying centre of [Erkelenz](https://en.wikipedia.org/wiki/Erkelenz "Erkelenz")), dated 5300 BC,[\[4\]](https://en.wikipedia.org/wiki/Well#cite_note-4) and [Eythra](https://en.wikipedia.org/wiki/Eythra "Eythra") in Schletz (an outlying centre of [Asparn an der Zaya](https://en.wikipedia.org/wiki/Asparn_an_der_Zaya "Asparn an der Zaya")) in [Austria](https://en.wikipedia.org/wiki/Austria "Austria"), dated 5200 BC.[\[5\]](https://en.wikipedia.org/wiki/Well#cite_note-5) The Neolithic Chinese discovered and made extensive use of deep drilled groundwater for drinking.\[[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed "Wikipedia:Citation needed")\] The Chinese text [The Book of Changes](https://en.wikipedia.org/wiki/I_Ching "I Ching"), originally a divination text of the Western Zhou dynasty (1046 -771 BC), contains an entry describing how the ancient Chinese maintained their wells and protected their sources of water.[\[6\]](https://en.wikipedia.org/wiki/Well#cite_note-Kuhn2004-6) A well excavated at the [Hemedu](https://en.wikipedia.org/wiki/Hemudu_culture "Hemudu culture") excavation site was believed to have been built during the neolithic era.[\[7\]](https://en.wikipedia.org/wiki/Well#cite_note-Chang2012-7) The well was cased by four rows of logs with a square frame attached to them at the top of the well. 60 additional tile wells southwest of Beijing are also believed to have been built around 600 BC for drinking and irrigation.[\[7\]](https://en.wikipedia.org/wiki/Well#cite_note-Chang2012-7)[\[8\]](https://en.wikipedia.org/wiki/Well#cite_note-8) [![](https://upload.wikimedia.org/wikipedia/commons/thumb/7/73/Model_well%2C_burial_find%2C_China%2C_Han_dynasty%2C_206_BC_to_220_AD%2C_earthenware_-_%C3%96stasiatiska_museet%2C_Stockholm_-_DSC09578.JPG/250px-Model_well%2C_burial_find%2C_China%2C_Han_dynasty%2C_206_BC_to_220_AD%2C_earthenware_-_%C3%96stasiatiska_museet%2C_Stockholm_-_DSC09578.JPG)](https://en.wikipedia.org/wiki/File:Model_well,_burial_find,_China,_Han_dynasty,_206_BC_to_220_AD,_earthenware_-_%C3%96stasiatiska_museet,_Stockholm_-_DSC09578.JPG) A Chinese ceramic model of a well with a water [pulley](https://en.wikipedia.org/wiki/Pulley "Pulley") system, excavated from a tomb of the [Han dynasty](https://en.wikipedia.org/wiki/Han_dynasty "Han dynasty") (202 BC – 220 AD) period In [Egypt](https://en.wikipedia.org/wiki/Egypt "Egypt"), [shadoofs](https://en.wikipedia.org/wiki/Shadoof "Shadoof") and [sakias](https://en.wikipedia.org/wiki/Sakia "Sakia") are used.[\[9\]](https://en.wikipedia.org/wiki/Well#cite_note-9)[\[10\]](https://en.wikipedia.org/wiki/Well#cite_note-10) The sakia is much more efficient, as it can bring up water from a depth of 10 metres (versus the 3 metres of the shadoof). The sakia is the Egyptian version of the [noria](https://en.wikipedia.org/wiki/Noria "Noria"). Some of the world's oldest known wells, located in Cyprus, date to 7000–8,500 BC.[\[11\]](https://en.wikipedia.org/wiki/Well#cite_note-11) Two wells from the Neolithic period, around 6500 BC, have been discovered in Israel. One is in Atlit, on the northern coast of Israel, and the other is in the Jezreel Valley.[\[12\]](https://en.wikipedia.org/wiki/Well#cite_note-12) Wells for other purposes came along much later, historically. The first recorded [salt well](https://en.wikipedia.org/wiki/Salt_well "Salt well") was dug in the Sichuan province of China around 2,250 years ago. This was the first time that ancient water well technology was applied successfully for the exploitation of salt, and marked the beginning of Sichuan's salt drilling industry.[\[6\]](https://en.wikipedia.org/wiki/Well#cite_note-Kuhn2004-6) The earliest known [oil wells](https://en.wikipedia.org/wiki/Oil_well "Oil well") were also drilled in China, in 347 CE. These wells had depths of up to about 240 metres (790 ft) and were drilled using [bits](https://en.wikipedia.org/wiki/Drill_bit "Drill bit") attached to [bamboo](https://en.wikipedia.org/wiki/Bamboo "Bamboo") poles.[\[13\]](https://en.wikipedia.org/wiki/Well#cite_note-ASTM-13) The oil was burned to evaporate [brine](https://en.wikipedia.org/wiki/Brine "Brine") and produce [salt](https://en.wikipedia.org/wiki/Sodium_chloride "Sodium chloride"). By the 10th century, extensive [bamboo](https://en.wikipedia.org/wiki/Bamboo "Bamboo") pipelines connected oil wells with salt springs. The ancient records of China and [Japan](https://en.wikipedia.org/wiki/Japan "Japan") are said to contain many allusions to the use of natural gas for lighting and heating. Petroleum was known as Burning water in Japan in the 7th century.[\[14\]](https://en.wikipedia.org/wiki/Well#cite_note-EB1911-14) [![](https://upload.wikimedia.org/wikipedia/commons/thumb/7/77/Uwaynat_bin_Hussain_water_well_near_Simaisma.jpg/250px-Uwaynat_bin_Hussain_water_well_near_Simaisma.jpg)](https://en.wikipedia.org/wiki/File:Uwaynat_bin_Hussain_water_well_near_Simaisma.jpg) Water well near [Simaisma](https://en.wikipedia.org/wiki/Simaisma "Simaisma"), eastern Qatar [![](https://upload.wikimedia.org/wikipedia/commons/thumb/b/b8/Leather_bucket_of_a_well.jpg/250px-Leather_bucket_of_a_well.jpg)](https://en.wikipedia.org/wiki/File:Leather_bucket_of_a_well.jpg) Leather bucket used for the water well [![](https://upload.wikimedia.org/wikipedia/commons/thumb/a/a6/Well%2C_Historical_Village_%2C_Bhaini_Sahib%2C_Ludhyana_%2C_Punjab_%2C_India.JPG/250px-Well%2C_Historical_Village_%2C_Bhaini_Sahib%2C_Ludhyana_%2C_Punjab_%2C_India.JPG)](https://en.wikipedia.org/wiki/File:Well,_Historical_Village_,_Bhaini_Sahib,_Ludhyana_,_Punjab_,_India.JPG) Well, Historical Village, Bhaini Sahib, [Ludhiana](https://en.wikipedia.org/wiki/Ludhiana "Ludhiana"), [Punjab](https://en.wikipedia.org/wiki/Punjab,_India "Punjab, India"), India [![](https://upload.wikimedia.org/wikipedia/commons/thumb/d/d6/Well.handdug.cased.mali.jpg/250px-Well.handdug.cased.mali.jpg)](https://en.wikipedia.org/wiki/File:Well.handdug.cased.mali.jpg) View into a hand-dug well cased with concrete rings. [Ouelessebougou](https://en.wikipedia.org/wiki/Ouelessebougou "Ouelessebougou"), Mali. [![](https://upload.wikimedia.org/wikipedia/commons/thumb/c/ca/Well_In_Kerala.JPG/250px-Well_In_Kerala.JPG)](https://en.wikipedia.org/wiki/File:Well_In_Kerala.JPG) A dug well in a village in [Kerala](https://en.wikipedia.org/wiki/Kerala "Kerala"), India [![](https://upload.wikimedia.org/wikipedia/commons/thumb/5/57/Open_Well_-_flower_bag_shaped_wall_and_podium_01.jpg/250px-Open_Well_-_flower_bag_shaped_wall_and_podium_01.jpg)](https://en.wikipedia.org/wiki/File:Open_Well_-_flower_bag_shaped_wall_and_podium_01.jpg) Well with a flower bag-shaped wall and podium Until recent centuries, all artificial wells were [pumpless](https://en.wikipedia.org/wiki/Pump "Pump") hand-dug wells of varying degrees of sophistication, and they remain a very important source of [potable water](https://en.wikipedia.org/wiki/Potable_water "Potable water") in some rural developing areas, where they are routinely dug and used today. Their indispensability has produced a number of literary references, literal and figurative, including the reference to the incident of [Jesus](https://en.wikipedia.org/wiki/Jesus "Jesus") meeting a woman at [Jacob](https://en.wikipedia.org/wiki/Jacob "Jacob")'s well ([John](https://en.wikipedia.org/wiki/Gospel_of_John "Gospel of John") 4:6) in the Bible and the "[Ding Dong Bell](https://en.wikipedia.org/wiki/Ding_Dong_Bell "Ding Dong Bell")" [nursery rhyme](https://en.wikipedia.org/wiki/Nursery_rhyme "Nursery rhyme") about a cat in a well. Hand-dug wells are excavations with diameters large enough to accommodate one or more people with shovels digging down to below the [water table](https://en.wikipedia.org/wiki/Water_table "Water table"). The excavation is braced horizontally to avoid landslide or erosion endangering the people digging. They can be lined with stone or brick; extending this lining upwards above the ground surface to form a wall around the well serves to reduce both contamination and accidental falls into the well. A more modern method called [caissoning](https://en.wikipedia.org/wiki/Caisson_\(engineering\) "Caisson (engineering)") uses reinforced concrete or plain concrete pre-cast well rings that are lowered into the hole. A well-digging team digs under a cutting ring and the well column slowly sinks into the [aquifer](https://en.wikipedia.org/wiki/Aquifer "Aquifer"), whilst protecting the team from collapse of the well [bore](https://en.wikipedia.org/wiki/Borehole "Borehole"). Hand-dug wells are inexpensive and low tech (compared to drilling) and they use mostly manual labour to access groundwater in rural locations of developing countries. They may be built with a high degree of community participation, or by local entrepreneurs who specialize in hand-dug wells. They have been successfully excavated to 60 metres (200 ft). They have low operational and maintenance costs, in part because water can be extracted by hand, without a pump. The water often comes from an aquifer or groundwater, and can be easily deepened, which may be necessary if the ground water level drops, by telescoping the lining further down into the aquifer. The yield of existing hand dug wells may be improved by deepening or introducing vertical tunnels or perforated pipes. Drawbacks to hand-dug wells are numerous. It can be impractical to hand dig wells in areas where hard rock is present, and they can be time-consuming to dig and line even in favourable areas. Because they exploit shallow aquifers, the well may be susceptible to yield fluctuations and possible contamination from surface water, including sewage. Hand dug well construction generally requires the use of a well trained construction team, and the capital investment for equipment such as concrete ring moulds, heavy lifting equipment, well shaft formwork, motorized de-watering pumps, and fuel can be large for people in developing countries. Construction of hand dug wells can be dangerous due to collapse of the well bore, falling objects and asphyxiation, including from dewatering pump exhaust fumes. The [Woodingdean Water Well](https://en.wikipedia.org/wiki/Woodingdean_Water_Well "Woodingdean Water Well"), hand-dug between 1858 and 1862, is the deepest hand-dug well at 392 metres (1,285 ft).[\[15\]](https://en.wikipedia.org/wiki/Well#cite_note-15) The [Big Well](https://en.wikipedia.org/wiki/Big_Well "Big Well") in [Greensburg, Kansas](https://en.wikipedia.org/wiki/Greensburg,_Kansas "Greensburg, Kansas"), is billed as the world's largest hand-dug well, at 109 feet (33 m) deep and 32 feet (9.8 m) in diameter. However, the Well of Joseph in the [Cairo Citadel](https://en.wikipedia.org/wiki/Cairo_Citadel "Cairo Citadel") at 280 feet (85 m) deep and the [Pozzo di San Patrizio](https://en.wikipedia.org/wiki/Pozzo_di_San_Patrizio "Pozzo di San Patrizio") (St. Patrick's Well) built in 1527 in [Orvieto, Italy](https://en.wikipedia.org/wiki/Orvieto "Orvieto"), at 61 metres (200 ft) deep by 13 metres (43 ft) wide[\[16\]](https://en.wikipedia.org/wiki/Well#cite_note-16) are both larger by volume. Driven wells may be very simply created in unconsolidated material with a well hole structure, which consists of a hardened drive point and a screen (perforated pipe). The point is simply hammered into the ground, usually with a tripod and driver, with pipe sections added as needed. A driver is a weighted pipe that slides over the pipe being driven and is repeatedly dropped on it. When [groundwater](https://en.wikipedia.org/wiki/Groundwater "Groundwater") is encountered, the well is washed of sediment and a pump installed.[\[17\]](https://en.wikipedia.org/wiki/Well#cite_note-17) Drilled wells are constructed using various types of drilling machines, such as top-head rotary, table rotary, or cable tool, which all use drilling stems that rotate to cut into the formation, thus the term "drilling." Drilled wells can be excavated by simple hand drilling methods (augering, sludging, jetting, driving, hand percussion) or machine drilling (auger, rotary, percussion, down the hole hammer). Deep rock rotary drilling method is most common. Rotary can be used in 90% of formation types (consolidated). Drilled wells can get water from a much deeper level than dug wells can − often down to several hundred metres.[\[18\]](https://en.wikipedia.org/wiki/Well#cite_note-18) Drilled wells with electric pumps are used throughout the world, typically in rural or sparsely populated areas, though many urban areas are supplied partly by municipal wells. Most shallow well drilling machines are mounted on large trucks, trailers, or tracked vehicle carriages. Water wells typically range from 3 to 18 metres (10–60 ft) deep, but in some areas it can go deeper than 900 metres (3,000 ft).\[[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed "Wikipedia:Citation needed")\] [![](https://upload.wikimedia.org/wikipedia/commons/thumb/5/59/Well_spudder_8606.jpg/250px-Well_spudder_8606.jpg)](https://en.wikipedia.org/wiki/File:Well_spudder_8606.jpg) [Cable tool](https://en.wikipedia.org/wiki/Drilling_rig#Cable_tool_drilling "Drilling rig") water well drilling rig in [Kimball, West Virginia](https://en.wikipedia.org/wiki/Kimball,_West_Virginia "Kimball, West Virginia") [![](https://upload.wikimedia.org/wikipedia/commons/thumb/e/e2/AquaBellaPickard-v.jpg/250px-AquaBellaPickard-v.jpg)](https://en.wikipedia.org/wiki/File:AquaBellaPickard-v.jpg) Israeli geologist [Leo Picard](https://en.wikipedia.org/wiki/Leo_Picard "Leo Picard") (white shirt) inspects a drilled water well outside the depopulated Palestinian village of [Bayt Naqquba](https://en.wikipedia.org/wiki/Bayt_Naqquba "Bayt Naqquba") Rotary drilling machines use a segmented steel drilling string, typically made up of 3m (10ft), 6 m (20 ft) to 8m (26ft) sections of steel tubing that are threaded together, with a [bit](https://en.wikipedia.org/wiki/Drill_bit#Well_drilling_bits "Drill bit") or other drilling device at the bottom end. Some rotary drilling machines are designed to install (by driving or drilling) a steel casing into the well in conjunction with the drilling of the actual bore hole. Air and/or water is used as a circulation fluid to displace cuttings and cool bits during the drilling. Another form of rotary-style drilling, termed mud rotary, makes use of a specially made mud, or drilling fluid, which is constantly being altered during the drill so that it can consistently create enough hydraulic pressure to hold the side walls of the bore hole open, regardless of the presence of a casing in the well. Typically, boreholes drilled into solid rock are not cased until after the drilling process is completed, regardless of the machinery used. The oldest form of drilling machinery is the [cable tool](https://en.wikipedia.org/wiki/Drilling_rig#Cable_tool_drilling "Drilling rig"), still used today. Specifically designed to raise and lower a bit into the bore hole, the spudding of the drill causes the bit to be raised and dropped onto the bottom of the hole, and the design of the cable causes the bit to twist at approximately 1⁄4 revolution per drop, thereby creating a drilling action. Unlike rotary drilling, cable tool drilling requires the drilling action to be stopped so that the bore hole can be bailed or emptied of drilled cuttings. Cable tool drilling rigs are rare as they tend to be 10x slower to drill through materials compared to similar diameter rotary air or rotary mud equipped rigs. Drilled wells are usually cased with a factory-made pipe, typically [steel](https://en.wikipedia.org/wiki/Steel "Steel") (in air rotary or cable tool drilling) or [plastic](https://en.wikipedia.org/wiki/Plastic "Plastic")/[PVC](https://en.wikipedia.org/wiki/PVC "PVC") (in mud rotary wells, also present in wells drilled into solid rock). The casing is constructed by welding, either chemically or thermally, segments of casing together. If the casing is installed during the drilling, most drills will drive the casing into the ground as the bore hole advances, while some newer machines will actually allow for the casing to be rotated and drilled into the formation in a similar manner as the bit advancing just below. PVC or plastic is typically solvent welded and then lowered into the drilled well, vertically stacked with their ends nested and either glued or splined together. The sections of casing are usually 6 metres (20 ft) or more in length, and 4 to 12 in (10 to 30 cm) in diameter, depending on the intended use of the well and local groundwater conditions. Surface contamination of wells in the United States is typically controlled by the use of a surface seal. A large hole is drilled to a predetermined depth or to a confining formation (clay or bedrock, for example), and then a smaller hole for the well is completed from that point forward. The well is typically cased from the surface down into the smaller hole with a casing that is the same diameter as that hole. The annular space between the large bore hole and the smaller casing is filled with [bentonite clay](https://en.wikipedia.org/wiki/Bentonite_clay "Bentonite clay"), concrete, or other sealant material. This creates an impermeable seal from the surface to the next confining layer that keeps contaminants from traveling down the outer sidewalls of the casing or borehole and into the [aquifer](https://en.wikipedia.org/wiki/Aquifer "Aquifer"). In addition, wells are typically capped with either an engineered well cap or seal that vents air through a screen into the well, but keeps insects, small animals, and unauthorized persons from accessing the well. At the bottom of wells, based on formation, a screening device, filter pack, slotted casing, or open bore hole is left to allow the flow of water into the well. Constructed screens are typically used in unconsolidated formations (sands, gravels, etc.), allowing water and a percentage of the formation to pass through the screen. Allowing some material to pass through creates a large area filter out of the rest of the formation, as the amount of material present to pass into the well slowly decreases and is removed from the well. Rock wells are typically cased with a PVC liner/casing and screen or slotted casing at the bottom, this is mostly present just to keep rocks from entering the pump assembly. Some wells use a filter pack method, where an undersized screen or slotted casing is placed inside the well and a filter medium is packed around the screen, between the screen and the borehole or casing. This allows the water to be filtered of unwanted materials before entering the well and pumping zone. - [![An automated water well system powered by a jet-pump](https://upload.wikimedia.org/wikipedia/en/thumb/8/8e/Jet-pump_System.svg/120px-Jet-pump_System.svg.png)](https://en.wikipedia.org/wiki/File:Jet-pump_System.svg "An automated water well system powered by a jet-pump") An automated water well system powered by a jet-pump - [![An automated water well system powered by a submersible pump](https://upload.wikimedia.org/wikipedia/en/thumb/2/28/Submersible-pump_System.svg/120px-Submersible-pump_System.svg.png)](https://en.wikipedia.org/wiki/File:Submersible-pump_System.svg "An automated water well system powered by a submersible pump") An automated water well system powered by a submersible pump - [![A water well system with a cistern](https://upload.wikimedia.org/wikipedia/commons/thumb/f/f1/Water_System_With_Cistern.svg/120px-Water_System_With_Cistern.svg.png)](https://en.wikipedia.org/wiki/File:Water_System_With_Cistern.svg "A water well system with a cistern") A water well system with a cistern - [![A water well system with a pressurized cistern](https://upload.wikimedia.org/wikipedia/commons/thumb/8/8e/Water_System_With_Pressurized_Cistern.svg/120px-Water_System_With_Pressurized_Cistern.svg.png)](https://en.wikipedia.org/wiki/File:Water_System_With_Pressurized_Cistern.svg "A water well system with a pressurized cistern") A water well system with a pressurized cistern - [![A section of a stainless steel screen well](https://upload.wikimedia.org/wikipedia/commons/thumb/5/5d/Screen_tube.JPG/120px-Screen_tube.JPG)](https://en.wikipedia.org/wiki/File:Screen_tube.JPG "A section of a stainless steel screen well") A section of a stainless steel screen well [![](https://upload.wikimedia.org/wikipedia/commons/thumb/c/c2/Water_well_types_wiki.svg/500px-Water_well_types_wiki.svg.png)](https://en.wikipedia.org/wiki/File:Water_well_types_wiki.svg) Water well types There are two broad classes of drilled-well types, based on the type of [aquifer](https://en.wikipedia.org/wiki/Aquifer "Aquifer") the well is in: - Shallow or unconfined wells are completed in the uppermost saturated aquifer at that location (the upper unconfined aquifer).\[[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed "Wikipedia:Citation needed")\] - Deep or confined wells are sunk through an impermeable stratum into an aquifer that is sandwiched between two impermeable strata (aquitards or aquicludes). The majority of deep aquifers are classified as artesian because the hydraulic head in a confined well is higher than the level of the top of the aquifer. If the hydraulic head in a confined well is higher than the land surface it is a "flowing" [artesian well](https://en.wikipedia.org/wiki/Artesian_well "Artesian well") (named after [Artois](https://en.wikipedia.org/wiki/Artois "Artois") in [France](https://en.wikipedia.org/wiki/France "France")).[\[19\]](https://en.wikipedia.org/wiki/Well#cite_note-19) [![](https://upload.wikimedia.org/wikipedia/commons/thumb/7/75/Old-fashioned_well_in_Finland.JPG/250px-Old-fashioned_well_in_Finland.JPG)](https://en.wikipedia.org/wiki/File:Old-fashioned_well_in_Finland.JPG) An old-fashioned water well in the countryside of [Utajärvi](https://en.wikipedia.org/wiki/Utaj%C3%A4rvi "Utajärvi"), [Finland](https://en.wikipedia.org/wiki/Finland "Finland") A special type of water well may be constructed adjacent to freshwater lakes or streams. Commonly called a collector well but sometimes referred to by the trade name Ranney well or [Ranney collector](https://en.wikipedia.org/wiki/Ranney_collector "Ranney collector"), this type of well involves sinking a caisson vertically below the top of the aquifer and then advancing lateral collectors out of the caisson and beneath the surface water body. Pumping from within the caisson induces infiltration of water from the surface water body into the aquifer, where it is collected by the collector well laterals and conveyed into the caisson where it can be pumped to the ground surface.\[[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed "Wikipedia:Citation needed")\] Two additional broad classes of well types may be distinguished, based on the use of the well: - production or pumping wells, are large diameter (greater than 15 cm in diameter) cased (metal, plastic, or concrete) water wells, constructed for extracting water from the aquifer by a [pump](https://en.wikipedia.org/wiki/Pump "Pump") (if the well is not [artesian](https://en.wikipedia.org/wiki/Artesian_aquifer "Artesian aquifer")).\[[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed "Wikipedia:Citation needed")\] [![](https://upload.wikimedia.org/wikipedia/commons/thumb/5/5c/Well_schematic.pdf/page1-250px-Well_schematic.pdf.jpg)](https://en.wikipedia.org/wiki/File:Well_schematic.pdf) Schematic diagram of a groundwater monitoring well - monitoring wells or [piezometers](https://en.wikipedia.org/wiki/Piezometer "Piezometer"), are often smaller diameter wells used to monitor the hydraulic head or sample the groundwater for chemical constituents. Piezometers are monitoring wells completed over a very short section of aquifer. Monitoring wells can also be completed at multiple levels, allowing discrete samples or measurements to be made at different vertical elevations at the same map location.[\[20\]](https://en.wikipedia.org/wiki/Well#cite_note-20) A water well constructed for pumping groundwater can be used passively as a monitoring well and a small diameter well can be pumped, but this distinction by use is common.\[[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed "Wikipedia:Citation needed")\] Before excavation, information about the geology, water table depth, seasonal fluctuations, recharge area and rate should be found if possible. This work can be done by a [hydrogeologist](https://en.wikipedia.org/wiki/Hydrogeologist "Hydrogeologist"), or a groundwater surveyor using a variety of tools including electro-seismic surveying,[\[21\]](https://en.wikipedia.org/wiki/Well#cite_note-21) any available information from nearby wells, geologic maps, and sometimes [geophysical imaging](https://en.wikipedia.org/wiki/Geophysical_imaging "Geophysical imaging"). These professionals provide advice that is almost as accurate a driller who has experience and knowledge of nearby wells/bores and the most suitable drilling technique based on the expected target depth. [![](https://upload.wikimedia.org/wikipedia/commons/thumb/9/9d/Groundwater_Contamination_Latin_America_Sm.png/250px-Groundwater_Contamination_Latin_America_Sm.png)](https://en.wikipedia.org/wiki/File:Groundwater_Contamination_Latin_America_Sm.png) [Waterborne diseases](https://en.wikipedia.org/wiki/Waterborne_diseases "Waterborne diseases") can be spread via a well which is contaminated with fecal pathogens from [pit latrines](https://en.wikipedia.org/wiki/Pit_latrine "Pit latrine"). [![](https://upload.wikimedia.org/wikipedia/commons/thumb/b/b4/Cleaning_a_well_in_Yaounde.jpg/250px-Cleaning_a_well_in_Yaounde.jpg)](https://en.wikipedia.org/wiki/File:Cleaning_a_well_in_Yaounde.jpg) Man cleaning a well in [Yaoundé](https://en.wikipedia.org/wiki/Yaound%C3%A9 "Yaoundé"), [Cameroon](https://en.wikipedia.org/wiki/Cameroon "Cameroon") [![](https://upload.wikimedia.org/wikipedia/commons/thumb/b/b4/Hand_water_pump_in_India_%283382861084%29.jpg/250px-Hand_water_pump_in_India_%283382861084%29.jpg)](https://en.wikipedia.org/wiki/File:Hand_water_pump_in_India_\(3382861084\).jpg) Hand pump to pump water from a well in a village near Chennai in India, where the well water might be polluted by nearby [pit latrines](https://en.wikipedia.org/wiki/Pit_latrine "Pit latrine"). Shallow pumping wells can often supply [drinking water](https://en.wikipedia.org/wiki/Drinking_water "Drinking water") at a very low cost. However, impurities from the surface easily reach shallow sources, which leads to a greater risk of contamination for these wells compared to deeper wells. Contaminated wells can lead to the spread of various [waterborne diseases](https://en.wikipedia.org/wiki/Waterborne_diseases "Waterborne diseases"). Dug and driven wells are relatively easy to contaminate; for instance, most dug wells are unreliable in the majority of the United States.[\[22\]](https://en.wikipedia.org/wiki/Well#cite_note-CEH-CID-22) Some research has found that, in cold regions, changes in river flow and flooding caused by extreme rainfall or snowmelt can degrade well water quality.[\[23\]](https://en.wikipedia.org/wiki/Well#cite_note-23) Most of the [bacteria](https://en.wikipedia.org/wiki/Bacteria "Bacteria"), [viruses](https://en.wikipedia.org/wiki/Viruses "Viruses"), [parasites](https://en.wikipedia.org/wiki/Parasite "Parasite"), and [fungi](https://en.wikipedia.org/wiki/Fungi "Fungi") that contaminate well water comes from [fecal material](https://en.wikipedia.org/wiki/Feces "Feces") from humans and other animals. Common bacterial contaminants include [E. coli](https://en.wikipedia.org/wiki/E._coli "E. coli"), [Salmonella](https://en.wikipedia.org/wiki/Salmonella "Salmonella"), [Shigella](https://en.wikipedia.org/wiki/Shigella "Shigella"), and [Campylobacter jejuni](https://en.wikipedia.org/wiki/Campylobacter_jejuni "Campylobacter jejuni"). Common viral contaminants include [norovirus](https://en.wikipedia.org/wiki/Norovirus "Norovirus"), [sapovirus](https://en.wikipedia.org/wiki/Sapovirus "Sapovirus"), [rotavirus](https://en.wikipedia.org/wiki/Rotavirus "Rotavirus"), [enteroviruses](https://en.wikipedia.org/wiki/Enterovirus "Enterovirus"), and [hepatitis A](https://en.wikipedia.org/wiki/Hepatitis_A "Hepatitis A") and [E](https://en.wikipedia.org/wiki/Hepatitis_E "Hepatitis E"). Parasites include [Giardia lamblia](https://en.wikipedia.org/wiki/Giardia_lamblia "Giardia lamblia"), [Cryptosporidium](https://en.wikipedia.org/wiki/Cryptosporidium "Cryptosporidium"), [Cyclospora cayetanensis](https://en.wikipedia.org/wiki/Cyclospora_cayetanensis "Cyclospora cayetanensis"), and [microsporidia](https://en.wikipedia.org/wiki/Microsporidia "Microsporidia").[\[22\]](https://en.wikipedia.org/wiki/Well#cite_note-CEH-CID-22) ### Chemical contamination \[[edit](https://en.wikipedia.org/w/index.php?title=Well&action=edit&section=10 "Edit section: Chemical contamination")\] Chemical contamination is a common problem with groundwater.[\[24\]](https://en.wikipedia.org/wiki/Well#cite_note-24) [Nitrates](https://en.wikipedia.org/wiki/Nitrate "Nitrate") from [sewage](https://en.wikipedia.org/wiki/Sewage "Sewage"), [sewage sludge](https://en.wikipedia.org/wiki/Sewage_sludge "Sewage sludge") or [fertilizer](https://en.wikipedia.org/wiki/Fertilizer "Fertilizer") are a particular problem for babies and young children. Pollutant chemicals include [pesticides](https://en.wikipedia.org/wiki/Pesticide "Pesticide") and [volatile organic compounds](https://en.wikipedia.org/wiki/Volatile_organic_compound "Volatile organic compound") from [gasoline](https://en.wikipedia.org/wiki/Gasoline "Gasoline"), [dry-cleaning](https://en.wikipedia.org/wiki/Dry-cleaning "Dry-cleaning"), the fuel additive [methyl tert-butyl ether](https://en.wikipedia.org/wiki/Methyl_tert-butyl_ether "Methyl tert-butyl ether") (MTBE), and [perchlorate](https://en.wikipedia.org/wiki/Perchlorate "Perchlorate") from rocket fuel, airbag inflators, and other artificial and natural sources.\[[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed "Wikipedia:Citation needed")\] Several minerals are also contaminants, including [lead](https://en.wikipedia.org/wiki/Lead "Lead") leached from brass fittings or old lead pipes, [chromium VI](https://en.wikipedia.org/wiki/Chromium_VI "Chromium VI") from electroplating and other sources, naturally occurring [arsenic](https://en.wikipedia.org/wiki/Arsenic "Arsenic"), [radon](https://en.wikipedia.org/wiki/Radon "Radon"), and [uranium](https://en.wikipedia.org/wiki/Uranium "Uranium")—all of which can cause cancer—and naturally occurring [fluoride](https://en.wikipedia.org/wiki/Fluoride "Fluoride"), which is desirable in low quantities to prevent [tooth decay](https://en.wikipedia.org/wiki/Tooth_decay "Tooth decay"), but can cause [dental fluorosis](https://en.wikipedia.org/wiki/Dental_fluorosis "Dental fluorosis") in higher concentrations.[\[22\]](https://en.wikipedia.org/wiki/Well#cite_note-CEH-CID-22) Some chemicals are commonly present in water wells at levels that are not toxic, but can cause other problems. [Calcium](https://en.wikipedia.org/wiki/Calcium "Calcium") and [magnesium](https://en.wikipedia.org/wiki/Magnesium "Magnesium") cause what is known as [hard water](https://en.wikipedia.org/wiki/Hard_water "Hard water"), which can precipitate and clog pipes or burn out water heaters. [Iron](https://en.wikipedia.org/wiki/Iron "Iron") and [manganese](https://en.wikipedia.org/wiki/Manganese "Manganese") can appear as dark flecks that stain clothing and plumbing, and can promote the growth of [iron and manganese bacteria](https://en.wikipedia.org/wiki/Iron_bacteria "Iron bacteria") that can form slimy black colonies that clog pipes.[\[22\]](https://en.wikipedia.org/wiki/Well#cite_note-CEH-CID-22) The quality of the well water can be significantly increased by lining the well, sealing the well head, fitting a self-priming hand pump, constructing an apron, ensuring the area is kept clean and free from stagnant water and animals, moving sources of contamination ([pit latrines](https://en.wikipedia.org/wiki/Pit_latrine "Pit latrine"), garbage pits, [on-site sewer systems](https://en.wikipedia.org/wiki/Onsite_sewage_facility "Onsite sewage facility")) and carrying out hygiene education. The well should be cleaned with 1% chlorine solution after construction and periodically every 6 months.\[[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed "Wikipedia:Citation needed")\] Well holes should be covered to prevent loose debris, animals, animal excrement, and wind-blown foreign matter from falling into the hole and decomposing. The cover should be able to be in place at all times, including when drawing water from the well. A suspended roof over an open hole helps to some degree, but ideally the cover should be tight fitting and fully enclosing, with only a screened air vent.\[[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed "Wikipedia:Citation needed")\] Minimum distances and soil percolation requirements between sewage disposal sites and water wells need to be observed. Rules regarding the design and installation of private and municipal septic systems take all these factors into account so that nearby drinking water sources are protected. Education of the general population in society also plays an important role in protecting drinking water.\[[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed "Wikipedia:Citation needed")\] Cleanup of [contaminated groundwater](https://en.wikipedia.org/wiki/Contaminated_groundwater "Contaminated groundwater") tends to be very costly. Effective [remediation of groundwater](https://en.wikipedia.org/wiki/Groundwater_remediation "Groundwater remediation") is generally very difficult. Contamination of groundwater from surface and subsurface sources can usually be dramatically reduced by correctly centering the casing during construction and filling the casing [annulus](https://en.wikipedia.org/wiki/Annulus_\(well\) "Annulus (well)") with an appropriate sealing material. The sealing material (grout) should be placed from immediately above the production zone back to surface, because, in the absence of a correctly constructed casing seal, contaminated fluid can travel into the well through the casing annulus. Centering devices are important (usually one per length of casing or at maximum intervals of 9 m) to ensure that the grouted annular space is of even thickness.\[[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed "Wikipedia:Citation needed")\] Upon the construction of a new test well, it is considered best practice to invest in a complete battery of chemical and biological tests on the well water in question. Point-of-use treatment is available for individual properties and treatment plants are often constructed for municipal water supplies that suffer from contamination. Most of these treatment methods involve the [filtration](https://en.wikipedia.org/wiki/Filtration "Filtration") of the contaminants of concern, and additional protection may be garnered by installing well-casing screens only at depths where contamination is not present.\[[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed "Wikipedia:Citation needed")\] Wellwater for personal use is often filtered with [reverse osmosis](https://en.wikipedia.org/wiki/Reverse_osmosis "Reverse osmosis") water processors; this process can remove very small particles. A simple, effective way of killing microorganisms is to bring the water to a full boil for one to three minutes, depending on location. A household well contaminated by microorganisms can initially be treated by shock chlorination using bleach, generating concentrations hundreds of times greater than found in community water systems; however, this will not fix any structural problems that led to the contamination and generally requires some expertise and testing for effective application.[\[22\]](https://en.wikipedia.org/wiki/Well#cite_note-CEH-CID-22) After the filtration process, it is common to implement an [ultraviolet](https://en.wikipedia.org/wiki/Ultraviolet_germicidal_irradiation "Ultraviolet germicidal irradiation") (UV) system to kill pathogens in the water. UV light affects the DNA of the pathogen by UV-C photons breaking through the cell wall. UV disinfection has been gaining popularity in the past decades as it is a chemical-free method of water treatment.[\[25\]](https://en.wikipedia.org/wiki/Well#cite_note-25) ## Environmental problems \[[edit](https://en.wikipedia.org/w/index.php?title=Well&action=edit&section=13 "Edit section: Environmental problems")\] A risk with the placement of water wells is [soil salination](https://en.wikipedia.org/wiki/Soil_salinity "Soil salinity") which occurs when the water table of the soil begins to drop and salt begins to accumulate as the soil begins to dry out.[\[26\]](https://en.wikipedia.org/wiki/Well#cite_note-26) Another environmental problem that is very prevalent in water well drilling is the potential for methane to seep through. The potential for soil salination is a large risk when choosing the placement of water wells. Soil salination is caused when the water table of the soil drops over time and salt begins to accumulate. In turn, the increased amount of salt begins to dry the soil out. The increased level of salt in the soil can result in the degradation of soil and can be very harmful to vegetation.\[[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed "Wikipedia:Citation needed")\] [Methane](https://en.wikipedia.org/wiki/Methane "Methane"), an asphyxiant, is a chemical compound that is the main component of natural gas. When methane is introduced into a confined space, it displaces oxygen, reducing oxygen concentration to a level low enough to pose a threat to humans and other aerobic organisms but still high enough for a risk of [spontaneous](https://en.wikipedia.org/wiki/Spontaneous_combustion "Spontaneous combustion") or externally caused explosion. This potential for explosion is what poses such a danger in regards to the drilling and placement of water wells.\[[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed "Wikipedia:Citation needed")\] Low levels of methane in drinking water are not considered toxic. When methane seeps into a water supply, it is commonly referred to as "methane migration". This can be caused by old natural gas wells near water well systems becoming abandoned and no longer monitored.\[[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed "Wikipedia:Citation needed")\] Lately,\[[when?](https://en.wikipedia.org/wiki/Wikipedia:Manual_of_Style/Dates_and_numbers#Chronological_items "Wikipedia:Manual of Style/Dates and numbers")\] however, the described wells/pumps are no longer very efficient and can be replaced by either [handpumps](https://en.wikipedia.org/wiki/Handpump "Handpump") or [treadle pumps](https://en.wikipedia.org/wiki/Treadle_pump "Treadle pump"). Another alternative is the use of self-dug wells, electrical deep-well pumps (for higher depths). [Appropriate technology](https://en.wikipedia.org/wiki/Appropriate_technology "Appropriate technology") organizations as [Practical Action](https://en.wikipedia.org/wiki/Practical_Action "Practical Action") are now\[[when?](https://en.wikipedia.org/wiki/Wikipedia:Manual_of_Style/Dates_and_numbers#Chronological_items "Wikipedia:Manual of Style/Dates and numbers")\] supplying information on how to build/set-up ([DIY](https://en.wikipedia.org/wiki/Do_it_yourself "Do it yourself")) handpumps and [treadle pumps](https://en.wikipedia.org/wiki/Treadle_pump "Treadle pump") in practice.[\[27\]](https://en.wikipedia.org/wiki/Well#cite_note-27)[\[28\]](https://en.wikipedia.org/wiki/Well#cite_note-28) ### PFAS/PFOS Fire fighting foam \[[edit](https://en.wikipedia.org/w/index.php?title=Well&action=edit&section=16 "Edit section: PFAS/PFOS Fire fighting foam")\] Per- and polyfluoroalkyl substances ([PFAS](https://en.wikipedia.org/wiki/Per-_and_polyfluoroalkyl_substances "Per- and polyfluoroalkyl substances") or PFASs) are a group of synthetic [organofluorine](https://en.wikipedia.org/wiki/Organofluorine_chemistry "Organofluorine chemistry") [chemical compounds](https://en.wikipedia.org/wiki/Chemical_compound "Chemical compound") that have multiple [fluorine](https://en.wikipedia.org/wiki/Fluorine "Fluorine") atoms attached to an [alkyl](https://en.wikipedia.org/wiki/Alkyl "Alkyl") chain. PFAS are a group of "forever chemicals" that spread very quickly and very far in ground water polluting it permanently. Water wells near certain airports where any foam fire fighting or training activities occurred up to 2010 are likely to be contaminated by PFAS. A study concluded that of ~39 million groundwater wells 9-20% are at [high risk of running dry](https://en.wikipedia.org/wiki/Water_security "Water security") if local groundwater levels decline by less than five meters, or – as with many areas and possibly more than half of major [aquifers](https://en.wikipedia.org/wiki/Aquifer "Aquifer")[\[29\]](https://en.wikipedia.org/wiki/Well#cite_note-29) – continue to decline.[\[30\]](https://en.wikipedia.org/wiki/Well#cite_note-30)[\[31\]](https://en.wikipedia.org/wiki/Well#cite_note-31)\[[further explanation needed](https://en.wikipedia.org/wiki/Wikipedia:Please_clarify "Wikipedia:Please clarify")\] ## Society and culture \[[edit](https://en.wikipedia.org/w/index.php?title=Well&action=edit&section=18 "Edit section: Society and culture")\] [![](https://upload.wikimedia.org/wikipedia/commons/thumb/6/6a/22-alimenti%2C_acqua_dolce%2CTaccuino_Sanitatis%2C_Casanatense_418.jpg/250px-22-alimenti%2C_acqua_dolce%2CTaccuino_Sanitatis%2C_Casanatense_418.jpg)](https://en.wikipedia.org/wiki/File:22-alimenti,_acqua_dolce,Taccuino_Sanitatis,_Casanatense_418.jpg) Water use, [Tacuinum Sanitatis](https://en.wikipedia.org/wiki/Tacuinum_Sanitatis "Tacuinum Sanitatis"), [Biblioteca Casanatense](https://en.wikipedia.org/wiki/Biblioteca_Casanatense "Biblioteca Casanatense") (14th century) [Springs](https://en.wikipedia.org/wiki/Spring_\(hydrology\) "Spring (hydrology)") and wells have had [cultural significance](https://en.wikipedia.org/wiki/Cultural_significance "Cultural significance") since [prehistoric](https://en.wikipedia.org/wiki/Prehistoric "Prehistoric") times, leading to the foundation of towns such as [Wells](https://en.wikipedia.org/wiki/Wells,_Somerset "Wells, Somerset") and [Bath](https://en.wikipedia.org/wiki/Bath,_Somerset "Bath, Somerset") in [Somerset](https://en.wikipedia.org/wiki/Somerset "Somerset"). Interest in health benefits led to the growth of [spa towns](https://en.wikipedia.org/wiki/Spa_town "Spa town") including many with wells in their name, examples being [Llandrindod Wells](https://en.wikipedia.org/wiki/Llandrindod_Wells "Llandrindod Wells") and [Royal Tunbridge Wells](https://en.wikipedia.org/wiki/Royal_Tunbridge_Wells "Royal Tunbridge Wells").[\[32\]](https://en.wikipedia.org/wiki/Well#cite_note-Burr-32) [Eratosthenes](https://en.wikipedia.org/wiki/Eratosthenes "Eratosthenes") is sometimes claimed to have used a well in his calculation of the [Earth's circumference](https://en.wikipedia.org/wiki/Earth%27s_circumference "Earth's circumference"); however, this is just a simplification used in a shorter explanation of [Cleomedes](https://en.wikipedia.org/wiki/Cleomedes "Cleomedes"), since Eratosthenes had used a more elaborate and precise method.[\[33\]](https://en.wikipedia.org/wiki/Well#cite_note-russo273277-33) Many incidents in the [Bible](https://en.wikipedia.org/wiki/Bible "Bible") take place around wells, such as the finding of a wife for [Isaac](https://en.wikipedia.org/wiki/Isaac "Isaac") in [Genesis](https://en.wikipedia.org/wiki/Book_of_Genesis "Book of Genesis") and [Jesus](https://en.wikipedia.org/wiki/Jesus "Jesus")'s talk with the Samaritan woman in the [Gospels](https://en.wikipedia.org/wiki/Gospels "Gospels").[\[34\]](https://en.wikipedia.org/wiki/Well#cite_note-34) ## A simple model for water well recovery \[[edit](https://en.wikipedia.org/w/index.php?title=Well&action=edit&section=19 "Edit section: A simple model for water well recovery")\] [![](https://upload.wikimedia.org/wikipedia/commons/thumb/5/57/Well_Recovery_diagram.jpg/250px-Well_Recovery_diagram.jpg)](https://en.wikipedia.org/wiki/File:Well_Recovery_diagram.jpg) Diagram of a water well partially filled to level z with the top of the aquifer at zT For a well with impermeable walls, the water in the well is resupplied from the bottom of the well. The rate at which water flows into the well will depend on the pressure difference between the ground water at the well bottom and the well water at the well bottom. The pressure of a column of water of height z will be equal to the weight of the water in the column divided by the cross-sectional area of the column, so the pressure of the ground water a distance zT below the top of the water table will be: ![{\\displaystyle P\_{g}=\\rho \\,g\\,z\_{T}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/638cbf760d9b102d42a0fe61424cfbb84eb644ed) where ρ is the mass density of the water and g is the acceleration due to gravity. When the water in the well is below the water table level, the pressure at the bottom of the well due to the water in the well will be less than Pg and water will be forced into the well. Referring to the diagram, if z is the distance from the bottom of the well to the well water level and zT is the distance from the bottom of the well to the top of the water table, the pressure difference will be: ![{\\displaystyle \\Delta P=\\rho \\,g\\,(z\_{T}-z)}](https://wikimedia.org/api/rest_v1/media/math/render/svg/311a95e84de02b5c6e319eedd8feb50ea181063e) Applying [Darcy's law](https://en.wikipedia.org/wiki/Darcy%27s_law "Darcy's law"), the volume rate (F) at which water is forced into the well will be proportional to this pressure difference: ![{\\displaystyle \\Delta P=R\\,F}](https://wikimedia.org/api/rest_v1/media/math/render/svg/5786632d6b2bb052677675191ea1e572c14aaa15) where R is the resistance to the flow, which depends on the well cross section, the pressure gradient at the bottom of the well, and the characteristics of the substrate at the well bottom. (e.g., porosity). The volume flow rate into the well can be written as a function of the rate of change of the well water level: ![{\\displaystyle F=A{\\frac {dz}{dt}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/2a739564c0695861c243527e15701b5380b474c5) Combining the above three equations yields a simple differential equation in z: ![{\\displaystyle RA{\\frac {dz}{dt}}=\\rho g(z\_{T}-z)}](https://wikimedia.org/api/rest_v1/media/math/render/svg/17afdd8ee77364f91732322618429ae09d2a4fe0) which may be solved: ![{\\displaystyle z=z\_{T}-(z\_{T}-z\_{0})e^{-t/\\tau }}](https://wikimedia.org/api/rest_v1/media/math/render/svg/16df3ea8a895dd6cd73a39111821a175b1c5d98d) where z0 is the well water level at time t=0 and τ is the well time constant: ![{\\displaystyle \\tau ={\\frac {RA}{\\rho g}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/01cd2f59d9c030817d81d1c8ab981b070faa8d3b) Note that if dz/dt for a depleted well can be measured, it will be equal to ![{\\displaystyle z\_{T}/\\tau }](https://wikimedia.org/api/rest_v1/media/math/render/svg/b72aa8e3c928e0d99f543788380c18fe540ac987) and the time constant τ can be calculated. According to the above model, it will take an infinite amount of time for a well to fully recover, but if we consider a well that is 99% recovered to be "practically" recovered, the time for a well to practically recover from a level at z will be: ![{\\displaystyle T\_{r}=\\tau \\ln \\left({\\frac {1-z/z\_{T}}{1-0.99}}\\right)}](https://wikimedia.org/api/rest_v1/media/math/render/svg/3db7a070422bcbfe86695fa9ed06fb1261b8d06a) For a well that is fully depleted (z=0) it would take a time of about 4\.6 τ to practically recover. The above model does not take into account the depletion of the aquifer due to the pumping which lowered the well water level (See [aquifer test](https://en.wikipedia.org/wiki/Aquifer_test "Aquifer test") and [groundwater flow equation](https://en.wikipedia.org/wiki/Groundwater_flow_equation "Groundwater flow equation")). Also, practical wells may have impermeable walls only up to, but not including the bedrock, which will give a larger surface area for water to enter the well.[\[35\]](https://en.wikipedia.org/wiki/Well#cite_note-Humboldt-35)[\[36\]](https://en.wikipedia.org/wiki/Well#cite_note-Inspectapedia-36) - Types of ancient wells - [Brick-lined well](https://en.wikipedia.org/wiki/Brick-lined_well "Brick-lined well") - [Castle well](https://en.wikipedia.org/wiki/Castle_well "Castle well"), for use in the castle - [Cistern](https://en.wikipedia.org/wiki/Cistern "Cistern"), ancient Greek - [Stepwell](https://en.wikipedia.org/wiki/Stepwell "Stepwell"), ancient India - Modern construction techniques - [Baptist well drilling](https://en.wikipedia.org/wiki/Baptist_well_drilling "Baptist well drilling"), simple technique - [Rodriguez well](https://en.wikipedia.org/wiki/Rodriguez_well "Rodriguez well"), for harvesting drinking water in polar regions - [Spring supply](https://en.wikipedia.org/wiki/Spring_supply "Spring supply"), piped water supply from the well - Uses - [Holy well](https://en.wikipedia.org/wiki/Holy_well "Holy well"), sacred wells in various religions - [Abraham's well](https://en.wikipedia.org/wiki/Abraham%27s_well "Abraham's well"), sacred well in Israel - [Ghat](https://en.wikipedia.org/wiki/Ghat "Ghat"), sacred in Hinduism and Buddhism - - Drainage and irrigation - [Drainage by wells](https://en.wikipedia.org/wiki/Drainage_by_wells "Drainage by wells") - [Shadoof](https://en.wikipedia.org/wiki/Shadoof "Shadoof"), an irrigation tool that is used to lift water from a water source onto land or into another waterway or basin - - Washing - [Lavoir](https://en.wikipedia.org/wiki/Lavoir "Lavoir"), public place for washing clothes. - [Fossil water](https://en.wikipedia.org/wiki/Fossil_water "Fossil water") - [History of water supply and sanitation](https://en.wikipedia.org/wiki/History_of_water_supply_and_sanitation "History of water supply and sanitation") - [Ancient water conservation techniques](https://en.wikipedia.org/wiki/Johad#Similar "Johad") - [Self-supply of water and sanitation](https://en.wikipedia.org/wiki/Self-supply_of_water_and_sanitation "Self-supply of water and sanitation") 1. [^](https://en.wikipedia.org/wiki/Well#cite_ref-1) Peltenburg, Edgar (2012). "East Mediterranean water wells of the 9th–7th millennium BC". In Klimscha, Florian (ed.). Wasserwirtschaftliche Innovationen im archäologischen Kontext. Von den prähistorischen Anfängen bis zu den Metropolen der Antike. Rahden/Westfalia: Leidorf. pp. 69–82\. 2. [^](https://en.wikipedia.org/wiki/Well#cite_ref-2) Galili, Ehud; Nir, Yaacov (1993). "The submerged Pre-Pottery Neolithic water well of Atlit-Yam, northern Israel, and its palaeoenvironmental implications". The Holocene. 3 (3): 265–270\. [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[1993Holoc...3..265G](https://ui.adsabs.harvard.edu/abs/1993Holoc...3..265G). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1177/095968369300300309](https://doi.org/10.1177%2F095968369300300309). [S2CID](https://en.wikipedia.org/wiki/S2CID_\(identifier\) "S2CID (identifier)") [130032420](https://api.semanticscholar.org/CorpusID:130032420). 3. [^](https://en.wikipedia.org/wiki/Well#cite_ref-3) Rybníček, Michal; Kočár, Petr; Muigg, Bernhard; Peška, Jaroslav; Sedláček, Radko; Tegel, Willy; Kolář, Tomáš (2020). ["World's oldest dendrochronologically dated archaeological wood construction"](https://www.sciencedirect.com/science/article/pii/S0305440320300066). Journal of Archaeological Science. 115 105082. [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[2020JArSc.115j5082R](https://ui.adsabs.harvard.edu/abs/2020JArSc.115j5082R). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1016/j.jas.2020.105082](https://doi.org/10.1016%2Fj.jas.2020.105082). [S2CID](https://en.wikipedia.org/wiki/S2CID_\(identifier\) "S2CID (identifier)") [213707193](https://api.semanticscholar.org/CorpusID:213707193). 4. [^](https://en.wikipedia.org/wiki/Well#cite_ref-4) ["Kückhovener Brunnen – Dorfgemeinschaft Kückhoven E. V."](http://www.dorfgemeinschaft-kueckhoven.de/unser-dorf/kueckhovener-brunnen/) \[[permanent dead link](https://en.wikipedia.org/wiki/Wikipedia:Link_rot "Wikipedia:Link rot")\] 5. [^](https://en.wikipedia.org/wiki/Well#cite_ref-5) Tegel W, Elburg R, Hakelberg D, Stäuble H, Büntgen U (2012). ["Early Neolithic Water Wells Reveal the World's Oldest Wood Architecture"](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3526582). PLOS ONE. 7 (12) e51374. [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[2012PLoSO...751374T](https://ui.adsabs.harvard.edu/abs/2012PLoSO...751374T). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1371/journal.pone.0051374](https://doi.org/10.1371%2Fjournal.pone.0051374). [PMC](https://en.wikipedia.org/wiki/PMC_\(identifier\) "PMC (identifier)") [3526582](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3526582). [PMID](https://en.wikipedia.org/wiki/PMID_\(identifier\) "PMID (identifier)") [23284685](https://pubmed.ncbi.nlm.nih.gov/23284685). 6. ^ [*a](https://en.wikipedia.org/wiki/Well#cite_ref-Kuhn2004_6-0) [b](https://en.wikipedia.org/wiki/Well#cite_ref-Kuhn2004_6-1) Kuhn, Oliver (2004-06-30). ["Ancient Chinese Drilling"](https://csegrecorder.com/articles/view/ancient-chinese-drilling). Canadian Society of Exploration Geophysicists. 29* (6). 7. ^ [*a](https://en.wikipedia.org/wiki/Well#cite_ref-Chang2012_7-0) [b](https://en.wikipedia.org/wiki/Well#cite_ref-Chang2012_7-1) Chang, Mingteh (2012). Forest Hydrology: An Introduction to Water and Forests* (3rd ed.). CRC Press (published November 1, 2012). p. 31. [ISBN](https://en.wikipedia.org/wiki/ISBN_\(identifier\) "ISBN (identifier)") [978-1-4398-7994-8](https://en.wikipedia.org/wiki/Special:BookSources/978-1-4398-7994-8 "Special:BookSources/978-1-4398-7994-8") . 8. [^](https://en.wikipedia.org/wiki/Well#cite_ref-8) Koon, Wee Kek (July 25, 2015). ["How the ancient Chinese looked after their drinking water"](https://www.scmp.com/magazines/post-magazine/article/1843012/how-ancient-chinese-looked-after-their-drinking-water). South China Morning Post. 9. [^](https://en.wikipedia.org/wiki/Well#cite_ref-9) ["Sakieh explication/difference vs Sakia"](http://www.britannica.com/eb/topic-518730/sakia). Britannica.com. Retrieved 2011-12-19. 10. [^](https://en.wikipedia.org/wiki/Well#cite_ref-10) ["Sakia explication"](http://www.britannica.com/eb/article-9001226/sakia#271043.hook). Britannica.com. Retrieved 2011-12-19. 11. [^](https://en.wikipedia.org/wiki/Well#cite_ref-11) ["Stone Age wells found in Cyprus"](https://news.bbc.co.uk/2/hi/europe/8118318.stm). BBC News. 12. [^](https://en.wikipedia.org/wiki/Well#cite_ref-12) Ashkenazi, Eli (November 9, 2012). ["Ancient Well Reveals Secrets of First Jezreel Valley Farmers"](https://www.haaretz.com/israel-news/ancient-well-reveals-secrets-of-first-jezreel-valley-farmers-1.476288). Haaretz. 13. [^](https://en.wikipedia.org/wiki/Well#cite_ref-ASTM_13-0) ["ASTM International – Standards Worldwide"](https://web.archive.org/web/20200801082953/https://www.astm.org/COMMIT/D02/to1899_index.html). www.astm.org. Archived from [the original](https://www.astm.org/COMMIT/D02/to1899_index.html) on 2020-08-01. Retrieved 2019-02-01. 14. [^](https://en.wikipedia.org/wiki/Well#cite_ref-EB1911_14-0) Joseph P. Riva Jr. and Gordon I. Atwater. ["petroleum"](http://www.britannica.com/EBchecked/topic/454269/petroleum). [Encyclopædia Britannica](https://en.wikipedia.org/wiki/Encyclop%C3%A6dia_Britannica "Encyclopædia Britannica"). Retrieved 2008-06-30. 15. [^](https://en.wikipedia.org/wiki/Well#cite_ref-15) ["Woodingdean Well"](http://www.mybrightonandhove.org.uk/page_id__6948_path__0p115p1224p597p.aspx). 2005. Retrieved 26 Jan 2010. 16. [^](https://en.wikipedia.org/wiki/Well#cite_ref-16) ["St. Patrick's Well"](http://www.umbriatravel.com/Orvieto/en/itineraries_Orvieto.asp). Umbriatravel.com. Retrieved 2011-12-19. \[[permanent dead link](https://en.wikipedia.org/wiki/Wikipedia:Link_rot "Wikipedia:Link rot")\] 17. [^](https://en.wikipedia.org/wiki/Well#cite_ref-17) ["How I drill a Well."](https://books.google.com/books?id=oiEDAAAAMBAJ&dq=popular+science+1930&pg=-PA77) Popular Science, April 1952, pp. 177–181. 18. [^](https://en.wikipedia.org/wiki/Well#cite_ref-18) Association), NKBA (National Kitchen and Bath (2013-10-29). [Kitchen & Bath Residential Construction and Systems](https://books.google.com/books?id=CVTjAQAAQBAJ&q=Drilled+wells+can+get+water+from+a+much+deeper+level+than+dug+wells+can%E2%80%94often+down+to+several+hundred+metres.&pg=PA178). John Wiley & Sons. [ISBN](https://en.wikipedia.org/wiki/ISBN_\(identifier\) "ISBN (identifier)") [978-1-118-71104-0](https://en.wikipedia.org/wiki/Special:BookSources/978-1-118-71104-0 "Special:BookSources/978-1-118-71104-0") . 19. [^](https://en.wikipedia.org/wiki/Well#cite_ref-19) ["Artesian Water and Artesian Wells \\| U.S. Geological Survey"](https://www.usgs.gov/water-science-school/science/artesian-water-and-artesian-wells). www.usgs.gov. 2018-10-09. Retrieved 2026-03-23. 20. [^](https://en.wikipedia.org/wiki/Well#cite_ref-20) Arnold, L.R.; Flynn, J.L.; Paschke, S.S. (2009-10-20). ["Design and installation of a groundwater monitoring-well network in the High Plains aquifer, Colorado"](https://pubs.usgs.gov/publication/ds456). USGS Report. Data Series. U.S. Geological Survey: 5. [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[2009usgs.rept....5A](https://ui.adsabs.harvard.edu/abs/2009usgs.rept....5A). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.3133/ds456](https://doi.org/10.3133%2Fds456). Retrieved 27 May 2024. 21. [^](https://en.wikipedia.org/wiki/Well#cite_ref-21) Du Preez, Michael. ["ELECTRO-SEISMIC SURVEYS APPLIED TO MODDELING OF GROUNDWATER FLOW SYSTEMS"](https://web.archive.org/web/20110531163202/http://aquamap.co.nz/uploads/pdfs/ELECTRO-SEISMIC%20SURVEYS%20APPLIED%20TO%20MODELING%20OF%20GROUNDWATER%20FLOW.pdf) (PDF). Bloemfontein, South Africa. Archived from [the original](http://aquamap.co.nz/uploads/pdfs/ELECTRO-SEISMIC%20SURVEYS%20APPLIED%20TO%20MODELING%20OF%20GROUNDWATER%20FLOW.pdf) (PDF) on 31 May 2011. Retrieved 21 April 2011. 22. ^ [*a](https://en.wikipedia.org/wiki/Well#cite_ref-CEH-CID_22-0) [b](https://en.wikipedia.org/wiki/Well#cite_ref-CEH-CID_22-1) [c](https://en.wikipedia.org/wiki/Well#cite_ref-CEH-CID_22-2) [d](https://en.wikipedia.org/wiki/Well#cite_ref-CEH-CID_22-3) [e](https://en.wikipedia.org/wiki/Well#cite_ref-CEH-CID_22-4) Committee on Environmental Health; Committee on Infectious Diseases (2009). ["Drinking water from private wells and risks to children"](https://doi.org/10.1542%2Fpeds.2009-0751). [Pediatrics](https://en.wikipedia.org/wiki/Pediatrics_\(journal\) "Pediatrics (journal)"). 123* (6): 1599–1605\. [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1542/peds.2009-0751](https://doi.org/10.1542%2Fpeds.2009-0751). [PMID](https://en.wikipedia.org/wiki/PMID_\(identifier\) "PMID (identifier)") [19482772](https://pubmed.ncbi.nlm.nih.gov/19482772). 23. [^](https://en.wikipedia.org/wiki/Well#cite_ref-23) Wiebe, Andrew J.; Rudolph, David L.; Pasha, Ehsan; Brook, Jacqueline M.; Christie, Mike; Menkveld, Paul G. (2021). ["Impacts of Event-Based Recharge on the Vulnerability of Public Supply Wells"](https://doi.org/10.3390%2Fsu13147695). Sustainability. 13 (14): 7695. [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[2021Sust...13.7695W](https://ui.adsabs.harvard.edu/abs/2021Sust...13.7695W). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.3390/su13147695](https://doi.org/10.3390%2Fsu13147695). [ISSN](https://en.wikipedia.org/wiki/ISSN_\(identifier\) "ISSN (identifier)") [2071-1050](https://search.worldcat.org/issn/2071-1050). 24. [^](https://en.wikipedia.org/wiki/Well#cite_ref-24) Association, American Water Works (2003). [Water Sources](https://books.google.com/books?id=iOIdnO03cgEC&q=Chemical+contamination+is+a+common+problem+with+groundwater&pg=PA141). American Water Works Association. [ISBN](https://en.wikipedia.org/wiki/ISBN_\(identifier\) "ISBN (identifier)") [978-1-58321-229-5](https://en.wikipedia.org/wiki/Special:BookSources/978-1-58321-229-5 "Special:BookSources/978-1-58321-229-5") . 25. [^](https://en.wikipedia.org/wiki/Well#cite_ref-25) Meulemans, C. C. E. (1987-09-01). "The Basic Principles of UV–Disinfection of Water". Ozone: Science & Engineering. 9 (4): 299–313\. [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[1987OzSE....9..299M](https://ui.adsabs.harvard.edu/abs/1987OzSE....9..299M). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1080/01919518708552146](https://doi.org/10.1080%2F01919518708552146). [ISSN](https://en.wikipedia.org/wiki/ISSN_\(identifier\) "ISSN (identifier)") [0191-9512](https://search.worldcat.org/issn/0191-9512). 26. [^](https://en.wikipedia.org/wiki/Well#cite_ref-26) ["Soil salination by placement of water wells mentioned in India"](https://web.archive.org/web/20090522010539/http://ngm.nationalgeographic.com/2009/06/cheap-food/bourne-text/1). Ngm.nationalgeographic.com. 2002-10-17. Archived from [the original](http://ngm.nationalgeographic.com/2009/06/cheap-food/bourne-text/1) on May 22, 2009. Retrieved 2011-12-19. 27. [^](https://en.wikipedia.org/wiki/Well#cite_ref-27) ["Practical Answers – Handpumps"](http://practicalaction.org/practicalanswers/product_info.php?products_id=198). Practicalaction.org. Retrieved 2011-12-19. 28. [^](https://en.wikipedia.org/wiki/Well#cite_ref-28) ["Treadle pump"](http://dev.practicalaction.org/?id=appeal_nepalpump). Dev.practicalaction.org. Retrieved 2011-12-19. 29. [^](https://en.wikipedia.org/wiki/Well#cite_ref-29) Famiglietti, James S.; Ferguson, Grant (23 April 2021). ["The hidden crisis beneath our feet"](https://www.science.org/doi/10.1126/science.abh2867). Science. 372 (6540): 344–345\. [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[2021Sci...372..344F](https://ui.adsabs.harvard.edu/abs/2021Sci...372..344F). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1126/science.abh2867](https://doi.org/10.1126%2Fscience.abh2867). [PMID](https://en.wikipedia.org/wiki/PMID_\(identifier\) "PMID (identifier)") [33888627](https://pubmed.ncbi.nlm.nih.gov/33888627). [S2CID](https://en.wikipedia.org/wiki/S2CID_\(identifier\) "S2CID (identifier)") [233353241](https://api.semanticscholar.org/CorpusID:233353241). Retrieved 10 May 2021. 30. [^](https://en.wikipedia.org/wiki/Well#cite_ref-30) ["The largest assessment of global groundwater wells finds many are at risk of drying up"](https://www.sciencedaily.com/releases/2021/04/210423130101.htm). ScienceDaily. Retrieved 10 May 2021. 31. [^](https://en.wikipedia.org/wiki/Well#cite_ref-31) Jasechko, Scott; Perrone, Debra (23 April 2021). ["Global groundwater wells at risk of running dry"](https://www.science.org/doi/10.1126/science.abc2755). Science. 372 (6540): 418–421\. [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[2021Sci...372..418J](https://ui.adsabs.harvard.edu/abs/2021Sci...372..418J). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1126/science.abc2755](https://doi.org/10.1126%2Fscience.abc2755). [ISSN](https://en.wikipedia.org/wiki/ISSN_\(identifier\) "ISSN (identifier)") [0036-8075](https://search.worldcat.org/issn/0036-8075). [PMID](https://en.wikipedia.org/wiki/PMID_\(identifier\) "PMID (identifier)") [33888642](https://pubmed.ncbi.nlm.nih.gov/33888642). [S2CID](https://en.wikipedia.org/wiki/S2CID_\(identifier\) "S2CID (identifier)") [233353207](https://api.semanticscholar.org/CorpusID:233353207). Retrieved 10 May 2021. 32. [^](https://en.wikipedia.org/wiki/Well#cite_ref-Burr_32-0) Burr, Thomas Benge (1766). [The History of Tunbridge Wells](https://web.archive.org/web/20210131221739/https://theweald.org/d10.asp?BookId=burr000). London. Archived from [the original](http://theweald.org/bk.asp?bookid=burr000) on 2021-01-31. Retrieved 2019-10-09. 33. [^](https://en.wikipedia.org/wiki/Well#cite_ref-russo273277_33-0) [Russo, Lucio](https://en.wikipedia.org/wiki/Lucio_Russo "Lucio Russo") (2004). The Forgotten Revolution. Berlin: Springer. pp. 273–277\. 34. [^](https://en.wikipedia.org/wiki/Well#cite_ref-34) Bromiley, Geoffrey W. (1982), International Standard Bible Encyclopedia: E-J, Wm. B. Eerdmans Publishing, p. 955, [ISBN](https://en.wikipedia.org/wiki/ISBN_\(identifier\) "ISBN (identifier)") [978-0-8028-3782-0](https://en.wikipedia.org/wiki/Special:BookSources/978-0-8028-3782-0 "Special:BookSources/978-0-8028-3782-0") 35. [^](https://en.wikipedia.org/wiki/Well#cite_ref-Humboldt_35-0) ["Well Flow Equations"](https://geology.humboldt.edu/courses/geology556/556_handouts/well_flow_equations.pdf) (PDF). Cal Poly Humboldt, Department of Geology. Retrieved June 13, 2022. 36. [^](https://en.wikipedia.org/wiki/Well#cite_ref-Inspectapedia_36-0) ["How Much Water Can the Well Deliver"](https://inspectapedia.com/water/Well_Flow_Rate.php). Inspectapedia. Retrieved June 13, 2022. - Driscoll, F. (1986). Groundwater and Wells. [St. Paul](https://en.wikipedia.org/wiki/St._Paul,_MN "St. Paul, MN"): Johnson Filtration Systems. [ISBN](https://en.wikipedia.org/wiki/ISBN_\(identifier\) "ISBN (identifier)") [978-0-9616456-0-1](https://en.wikipedia.org/wiki/Special:BookSources/978-0-9616456-0-1 "Special:BookSources/978-0-9616456-0-1") . - Raymond Rowles (1995). Drilling for Water (2nd ed.). Avebury, Cranfield University. [ISBN](https://en.wikipedia.org/wiki/ISBN_\(identifier\) "ISBN (identifier)") [1-85628-984-2](https://en.wikipedia.org/wiki/Special:BookSources/1-85628-984-2 "Special:BookSources/1-85628-984-2") . [![Wikisource logo](https://upload.wikimedia.org/wikipedia/commons/thumb/4/4c/Wikisource-logo.svg/40px-Wikisource-logo.svg.png)](https://en.wikipedia.org/wiki/File:Wikisource-logo.svg) - [Sustainable Groundwater Development theme of the Rural Water Supply Network (RWSN)](http://www.rural-water-supply.net/en/sustainable-groundwater-management) - [Water Portal – Akvopedia](http://akvopedia.org/wiki/Water_Portal) [Archived](https://web.archive.org/web/20141018231204/http://akvopedia.org/wiki/Water_Portal) 2014-10-18 at the [Wayback Machine](https://en.wikipedia.org/wiki/Wayback_Machine "Wayback Machine") - [Sustainable Sanitation and Water Management Toolbox](http://www.sswm.info/) - [U.S. Centers for Disease Control and Prevention (CDC) Healthy Water – Water Wells](https://www.cdc.gov/healthywater/drinking/private/wells/index.html) Site covering well basics, guidelines for proper siting and location of wells to avoid contamination, well testing, diseases related to wells, emergency well treatment and other topics. - [US Geological Survey – Ground water: Wells](https://ga.water.usgs.gov/edu/earthgwwells.html) - [US Geological Survey – Water Science Pictures Flowing Artesian Well](https://ga.water.usgs.gov/edu/gwartesian.html) - [Drilling wells 18 extremely useful questions and answers](https://www.euforaje.ro/foraje-puturi/) - [American Ground Water Trust](http://agwt.org/) - [Lifewater International Technical Library](http://www.lifewater.org/resources/ground_water.html#GW) [Archived](https://web.archive.org/web/20130616030412/http://www.lifewater.org/resources/ground_water.html#GW) 2013-06-16 at the [Wayback Machine](https://en.wikipedia.org/wiki/Wayback_Machine "Wayback Machine") - [Well Construction Technical Resources for NGOs](http://www.watersanitationhygiene.org/References/Technical%20Resources%20-%20Wells.htm)
Shard	152 (laksa)
Root Hash	17790707453426894952
Unparsed URL	org,wikipedia!en,/wiki/Well s443