artesian flow

An artesian well is a well where water flows naturally to the surface due to hydrostatic pressure, without needing a pump. This occurs when a permeable rock layer, like sandstone, saturated with water (an aquifer), is situated between impermeable layers. If this layer is exposed at a higher elevation where it receives water, the weight of the water creates pressure that forces it up when a well is drilled into the aquifer.123

Artesian springs can also form where water escapes through natural breaks in the overlying rock. While artesian systems can be a significant water source, over-drilling has led to reduced pressure in many areas, necessitating pumps. The term "artesian" originates from Artois, a region in France where such wells were historically bored.145