Even though the water from an irrigation well might not be used for drinking water, contamination from it can affect the quality of water from nearby drinking water wells. For this reason, it is important to make sure that all wells are properly constructed and protected as much as possible.
As water is pumped from a well, ground water flows from the surrounding aquifer into the well. This causes a cone-shaped depression in the ground water surface around the well where the water has been pumped out. If the water in the aquifer were not moving, this cone of depression would be a circle. However, ground water usually is flowing very slowly, and, as a result, the water table usually is sloped slightly. The slope of the ground water surface generally follows the slope of the ground surface, with ground water flow from highland areas toward river valleys, lakes and the ocean. Because of this flow, the cone-shaped depression in the ground water surface around a pumped well usually is distorted.