A water well pump is a device used to draw water up from a well for delivery to a home or other structure. Pumps are necessary in sunk wells because the water cannot rise to the surface on its own. There are a number of different designs available for various applications, including solar pumps and wind-driven pumps for water systems that are off the electrical grid. A well specialist can install, maintain, and repair water well pump systems.
Two common water well pump designs are the jet pump and submersible pump. Both involve extending a line into the well and using an electric motor to pull water to the surface when required. Some designs fill a reserve tank with water so there will always be some water available, while others deliver water on demand. As people in a structure use water at the taps and in other locations, they trigger the well pump to run, bringing up more water for their use.
There are some needs specific to water well pumps that must be considered in their design and installation. One is clogging. Wells can have detritus, especially in the dry season when the water nears the low point, and some are also very rich in minerals that can form deposits on pump components. This can clog the head of the pump, slowing the delivery of water and eventually stopping it altogether. The pumping mechanism may have a cage or screen to limit clogs.
Another issue is priming. The water well pump is designed to work with water in the line. When air pockets develop, as might occur if the power goes out and someone drains the line, the pump cannot suck up water. The operator needs to manually prime the line to fill it with water again so the pump can start to run. Some water well systems shut off automatically if the top of the pump rises above the water or the power goes out, to keep the line primed until the problem can be addressed.
The water well pump is typically small, and cannot exceed the output of the well, or it would quickly drain the well in daily operation. It may be housed in a pump house separate from the building. In extremely cold climates, the pump and pipes may need to be wrapped to prevent freezing in the winter. The pump may also directly supply a water tank for firefighting and emergency purposes.