In an artesian well, the water can leap high into the air like a geyser from its prison far below the surface of the earth. The name comes from the Artois region in northern France where the first European well of this kind was drilled more than 800 years ago.

Artesian wells are possible only under certain conditions. There must be a layer of porous rock or sand that is buried between two layers of solid rock impervious to water. Somewhere this porous layer must be exposed to the surface so that water falling as rain or snow will sink downward until it is trapped between the solid, watertight layers above and below.