Abstract: A valve controlled flushing system for a tank-type toilet installation comprises a siphon flush valve, a control valve that allows supply water to flow into the tank to initiate siphonic action, to supplement flow through the siphon flush valve and to refill the tank, which control valve utilizes a piston which is ordinarily seated in a closed position by supply line pressure, and an actuating valve to relieve the pressure on the piston of the control valve thus initiating the flushing cycle. In the preferred embodiment, the control valve utilizes a pressure biased piston which is ordinarily seated in a closed position against the water supply by supply line pressure which is transferred by a bypass circuit to a timing pressure chamber behind and exposed to the rear face of the piston.