Diagram of a Nonpumping Well

An idle (nonpumping) well with a screen that is long enough to intersect different parts of an aquifer having different hydraulic heads will allow water and contaminants to migrate from one location within the aquifer to another by way of the wellbore. The movement can be downward or upward, depending on the direction of the hydraulic gradient, and can expand the volume of aquifer containing contaminated water that flows to the well when it is pumped. Modified from p. 63, USGS Circular 1385.