may be the type described in my u s pat no 4 145 774 in either case depression of the end of the handle 26 raises the discharge valve closure 10 to permit the water to begin flowing out through the discharge drain 28 the buoyancy chamber 18 is provided with a drain hole 30 in its bottom and a small bleeder hole 32 relatively higher than the drain hole 30 and formed through the wall of the buoyancy chamber below the sealing portion 14 with a conventional lever arm 24 and handle 26 a full flush utilizing all of the water in the tank is accomplished by depressing the handle 26 and holding it down until all of the water has exhausted from the water tank the handle is then released and the discharge valve closure falls closed to permit the tank to refill a short or reduced water volume flush is accomplished by depressing the conventional handle 26 and then releasing it permitting the lever 24 to fall downwardly then as the water level 34 falls water enters the buoyancy chamber 18 through the drain hole 30 as air bubbles upwardly from the bleeder hole 32 when the net buoyancy of the discharge valve closure and any remaining trapped air becomes negative the discharge valve closure falls into sealing engagement against the valve seat 16 if the handle and lever arm are as disclosed in my u s pat no 4 145 774 a full flush utilizing all of the water in the tank is accomplished by depressing the handle 26 and releasing it so that it remains biased in its upper bistable position in order to accomplish a reduced water volume flush the actuating handle is immediately raised after being depressed as.