Which component of a water well system is responsible for controlling surface water entry?

The casing of a water well system is a crucial component designed to control the entry of surface water and protect the well from external contaminants. It consists of a pipe that is installed in the wellbore and extends from the surface down into the water-bearing formation. The casing creates a barrier against the infiltration of surface water, soil, and other potential sources of pollution, ensuring that the groundwater drawn from the well remains clean and safe for use.

The wellhead, while important for sealing the top of the well and providing access to the well, does not directly control surface water entry in the same manner as the casing. The pump is responsible for lifting water to the surface but does not play a role in preventing contamination from surface sources. The screen, which is located at the lower end of the casing, is designed to allow water to enter the well while filtering out larger particles, but it is the casing that provides the primary defense against surface water infiltration.

Thus, the casing is fundamental in maintaining the integrity and quality of the groundwater by effectively controlling and minimizing the entrance of surface water into the well system.