What is an artesian well?

An artesian well is defined as a well where water rises above the level of the aquifer due to the presence of pressure in the confined aquifer. In an artesian system, the water is trapped between impermeable layers of rock or sediment, creating pressure within the aquifer. When a well is drilled into this confined aquifer, the pressure can cause the water to rise naturally to the surface or even beyond the level of the aquifer itself, without the need for pumping. This phenomenon is due to the hydraulic pressure that is exerted by the surrounding water in the aquifer.

In contrast, wells that are not drilled into an aquifer do not have access to this pressure, as they are not tapping into a confined water supply. Surface water wells, which extract water from lakes or rivers, do not involve aquifers at all. Shallow wells in riverbeds typically draw from unconfined aquifers or surface water rather than experiencing the pressure dynamics that characterize artesian wells. Therefore, the defining feature of an artesian well is its ability to allow water to rise due to the pressure present in the aquifer, distinguishing it from other types of wells.