What is an artesian well?
In some areas, artesian wells are a major source of water, especially in arid areas that are next to mountain ranges that receive precipitation.
Artesian wells withdraw water from an aquifer confined between two impermeable layers, where water is under hydrostatic pressure and can freely rise until it reaches the surface.
Water in an artesian well enters through the exposed side of an aquifer. Water infiltrates and is confined in spaces with high hydrostatic pressure. If you drill a well to the confined layer, the hydrostatic pressure in the aquifer will make the water rise to the surface of the well. However, the rapid development of new wells has reduced hydrostatic pressure and many artesian wells now need to be outfitted with pumps.
Some artesian waters may be very poor quality and cause serious damage on the surface or contaminate an overlaying aquifer. Water quality can be affected by the depth of the well. Water from bedrock formations, such as deep sandstone formations, may contain concentrations of arsenic that could pose a health concern.