A system for vacuuming out sediment when installed on the inside of a gravity feed, elevated potable water tank or tower holding water at a pressure head of the kind having a riser serving as a water inlet and outlet. The system having a manifold installed along the bottom wall of the tank or tower connected to a plurality of downwardly directed nozzles. The manifold is connected to a drain pipe passing down through the riser and is supported so that the nozzles are positioned above the bottom wall in the vicinity of the sediment. When water is allowed to flow through the drain pipe, the pressure head causes sediment which may otherwise be a health risk and promote electrolytic corrosion to be vacuumed out by the nozzles.