A water pump is made up of multiple tiny elements that work together to form a functional mechanism. The hub/pulley, bearing, body/house, seal, and impeller are the most basic components. They can be found in almost any water pump. The exception is electric pumps, which do not have an impeller. The hub/pulley structure provides a solid foundation for the pump to stand on. It also creates an opening through which water can flow. This is known as the "inlet" side of the pump. The outlet side is where water leaves the pump and flows into your hose or pipe. Some pumps have two hubs/pulleys: one at each end. These allow the pump to function even when one side is clogged with debris. Bearing housings hold the bearings that connect the shaft to the hub/pulley. They are usually made of steel or plastic. If you look inside a working pump, you should see three bearings: one inside each housing. These allow the shaft to turn but protect it from being damaged by objects in the water. The body/house keeps water out while allowing the shaft to rotate.