Abstract: The tank of a water closet has an overflow control apparatus operatively associated therewith for selectively applying a closing force to a flush valve, adapted for movement between an open position communicating water from the tank to a bowl of the water closet and a closed position stopping such communication. In the preferred embodiment of this invention, the overflow control apparatus comprises a weighted plunger reciprocally mounted in the tank, above the flush valve, for being selectively released by a reciprocal trip member to apply the closing force to the flush valve. Release is effected automatically in response to the water in the bowl exceeding a predetermined level and pivoting of a float mounted in the bowl.