The new route added several locks to the canal, making water supply problems more severe. Because of the way the system of locks work, water is lost from the upper part of a canal each time a vessel passes through. This is a particular issue for the pound between Bradford Lock at Bradford on Avon and the Bath Locks, where a series of locks need to be opened each time the gates are opened. Most lock gates are not watertight, therefore some water leaks from the higher levels of the canal to those lower down. The water has to be replaced, or eventually the upper levels of the canal would not hold enough water to be navigable. Canals are usually fed by diverting water from streams and rivers into the upper parts of the canal, but if no suitable source is available or sufficient, a pumping station, such as the one at Claverton, can be used to maintain the water level. Crofton Pumping Station was built to supply water to the summit pound of the canal, opening in 1810 but, unlike Claverton, was powered by steam.