From
http://www.dcwasa.com/about/facilities.cfm:
The water storage and pumping responsibilities are shared by DCWASA and the Washington Aqueduct. DCWASA operates four treated water pumping stations (Anacostia, Bryant Street, Fort Reno, and 16th & Alaska), and eight reservoirs and elevated tanks. The Washington Aqueduct operates the Dalecarlia Pump Station and three reservoirs (Foxhall, Van Ness, and Fort Reno).