WorldWide Drilling Resource

14 DECEMBER 2015 WorldWide Drilling Resource ® Artesian Water and Artesian Wells Adapted from Information Provided by the U.S. Geological Survey Water companies often sell “artesian-well drinking water”. Is this water different from other bottled water taken from springs? The water might not be different, but the way it comes to the surface is. Groundwater in aquifers between layers of poorly permeable rock, such as clay or shale, can be confined under pressure. If such a confined aquifer is tapped by a well, water will rise above the top of the aquifer and may even flow from the well onto the land surface. 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, 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. Deep wells drilled into rock to intersect the water table and reaching far below it are often called artesian wells in ordinary conversation, but this is not necessarily an accurate use of the term. Such deep wells may be just like ordinary, shallower wells; great depth alone 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 left shows an artesian well with the potentiometric surface being just above the land surface, but, as the picture above shows, artesian pressure can be very strong! Editor’s Note: In between our print issues, the WWDR Team prepares an electronic newsletter called E-News Flash . Based on readership, this was the most popular E-News Flash article of the month. Get in on the action and subscribe today at: www.worldwidedrillingresource.com --- *+ )#)('-()$* !(& )(%#'" +)""+ ,'.*,+ -'"/ 0 . 1 1 1 1