Abstract: A float has a bore which slidably embraces the overflow tube in a toilet tank. The float carries a valve actuator therebelow with structure which permits adjustment of the downward position of the valve actuator. The float and/or valve actuator may be non-round in order to fit closely adjacent the wall of the toilet tank. When the flapper valve at the bottom of the toilet tank is raised to release flush water, the float descends with lowering water leve and the actuator closes the flapper valve before all toilet tank water is released, to thereby conserve water.