What is Artesian Water?

Definition of Artesian:

Per the FDA’s Federal Register: The name of water …tapping a confined aquifer in which the water level stands at some height above the top of the aquifer is ‘‘artesian water’’, Artesian water …must not be under the direct influence of surface water as defined in 40 CFR 141.2.

Artesian aquifer

From Wikipedia, the free encyclopedia: An artesian aquifer is a confined aquifer containing groundwater that will flow upward through a well, called an artesian well, without the need for pumping. Water may even reach the ground surface if the natural pressure is high enough, in which case the well is called a flowing artesian well.

An aquifer is a layer of soft rock, like limestone or sandstone, that absorbs water from an inlet path. Porous stone is confined between impermeable rocks or clay. This keeps the pressure high, so when the water finds an outlet, it overcomes gravity and goes up instead of down. The recharging of aquifers happens when the water table at its recharge zone is at a higher elevation than the head of the well.

Artesian well.

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  Geological strata giving rise to an artesian well.

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  Schematic of an artesian well

   

  A flowing (artesian) well

  It comes to the earth's surface a bit differently. Water in aquifers between layers of permeable rock, clay or shale, confined under pressure are artesian aquifers. If such a confined aquifer is tapped by a well, water will rise above the top of the aquifer. Water confined in this way is said to be under artesian pressure, and the aquifer is called an artesian aquifer. The word artesian comes from the town of Artois in France, the old Roman city of Artesium, where the best known flowing artesian wells were drilled in the Middle Ages. The level to which water will rise in tightly cased wells in artesian aquifers is called the potentiometric surface.

  Great depth does not automatically make them artesian wells. The word artesian, properly used, refers to situations where the water is confined under pressure below layers of relatively impermeable rock. The picture to the right shows an artesian well with the potentiometric surface being just above the land surface, but artesian pressure can be very strong!