Abstract: A reservoir system for storing and selectively outputting a large quantity of water for flushing animal wastes from adjacent hoghouses or other pens. An above-ground tank is provided with a plurality of water output orifices which are sealed against leakage by flexible seal plates adapted to be selectively opened and closed by flushing valves. Each of the flushing valves comprises a rigid, tubular valve guide sleeve mounted within the water output orifices. Each sleeve includes a plurality of vent mouths radially spaced apart about its lower base. An elongated, rigid piston fitted within each sleeve is controlled by a rigid rod which extends downwardly from a top-mounted crank assembly. The crank is driven by a motor actuated by a user-programmable timer circuit. When the motor is actuated the crank assembly rotates and raises the pistons, and water flows through the vent orifices, the output orifices, to be channeled onto the subfloor of the hoghouses.