Water pumps are almost always belt driven devices which circulate coolant throughout the engine. Some water pumps are electrical, although these are normally aftermarket additions designed to free up horsepower that would otherwise be consumed by the belt driven pump. As the serpentine or v-belt spins the pulley, a shaft connects to an impeller inside the pump housing which provides the pressure and flow necessary to keep the coolant moving.
Water pumps can wear down over time, however dirty or low coolant levels and not regularly changing the oil will contribute to this wear and cause the pump to wear faster. Rough driving conditions will also play a factor. When a water pump begins to fail it will nearly always leak.
Replacing water pumps will vary from vehicle to vehicle, with a major factor often being how easily accessable they are.
We stock and sell a wide variety of quality water pumps from these manufacturers: