Geologicalstrata giving rise to an artesian wellSchematic of an artesian wellU.S. NavySeabees tapping an artesian well inHelmand Province, Afghanistan
Anartesian well is awell that bringsgroundwater to the surface without pumping because it is under pressure within a body of rock or sediment known as anaquifer.[1] When trapped water in an aquifer is surrounded by layers ofimpermeable rock or clay, which apply positive pressure to the water, it is known as anartesian aquifer.[1] If a well were to be sunk into an artesian aquifer, water in the well-pipe would rise to a height corresponding to the point wherehydrostatic equilibrium is reached.[1]
A well drilled into such an aquifer is called anartesian well.[1] If water reaches the ground surface under the natural pressure of the aquifer, the well is termed aflowing artesian well.[2][3]
Fossil water aquifers can also be artesian if they are under sufficient pressure from the surrounding rocks, similar to how many newly tappedoil wells are pressurized.
Artesian well near the Myllylähde spring inAlastaro, Finland
Not all aquifers are artesian (i.e., water table aquifers occur where the groundwater level at the top of the aquifer is at equilibrium with atmospheric pressure). Aquifers recharge when the water table at its recharge zone is at a higherelevation than the head of the well.
The first mechanically accurate explanation for artesian wells was given byAl-Biruni.[4] Artesian wells were named afterArtois inFrance, where many artesian wells were drilled byCarthusian monks from 1126.[5]
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