Abstract: An improved water sensor unit wherein a plurality of water-related appliances or equipment can be simultaneously monitored and, in the event of sensing water with respect to any one of the several items being monitored, appropriate action is taken, such as shutting off the power to the unit and simultaneously shutting off the water supply to that particular unit. The sensor unit comprises a plurality of electronic circuits which include thermal circuit breakers acting as a "fault memory." When a fault occurs, the circuit breakers are tripped. Thus, the fault condition will be "remembered" indefinitely until human intervention.