Abstract: A ground fault interrupter (GFI) circuit is wired to a main circuit breaker panel. A first output of the ground fault interrupter circuit provides electrical current to a solenoid valve that controls the supply of cold water to a conventional hot water heater. The solenoid valve is held in its open position by 110 V. alternating current and is closed by spring biasing means when the current is cut off. The other output of the GFI circuit provides 110 V. alternating current to a leak detector. A leak detecting system directs leakage to a collector wherein the presence of water in the collector completes the circuit between the hot wire and ground of the second outlet. When the circuit is shorted out to ground by the presence of water the GFI circuit is tripped at the main circuit breaker panel and simultaneously cuts off current to the solenoid valve controlling the flow of water to the heater permitting the spring to bias the valve shut and preventing any water damage due to leakage.