A lift station is used to transfer liquid that cannot flow by gravity on its own. This pump system is powered by a close-coupled electric motor. The pumps operate quietly and are cooled by the moving liquid to maximize their lifespan. Most pump stations are designed for multiple pump installations. The duplex system is the most common where the two pumps alternate in operation to equalize the wear of the pumps and to keep the wet well from solids build-up. The multiple pump system offers continued operation in the case of a pump failure, removal for servicing, and also provides extra capacity in times of extraordinary loading.