A pumped storage electricity generating system that includes a water feed line for introducing water into a pressure vessel. Water flow valves communicate with the pressure vessel to control introduction of water into the pressure vessel. A push plate is mounted for movement in the pressure vessel between opposed first and second motors, for example, hydraulic radial piston motors adapted for reciprocating the push plate linearly between a first direction wherein water is drawn into the pressure vessel through the water flow valves and a second direction wherein water is conveyed downstream through the water discharge line under pressure to the hydroelectric turbine. Other embodiments are double-acting and convey water to the turbine on each stroke.