Abstract: A remotely-actuated residential water supply cut-off system is disclosed. A remotely-actuated cut-off valve interposed in a residential water line downstream of a pressure-reducing valve. An electronic actuator is mounted on the cut-off valve and is remotely actuated to drive a DC motor in a clockwise or counterclockwise direction to open or close the cut-off valve in response to a received signal. The electronic actuator includes a transceiver, a microcontroller and a motor. The microcontroller drives the motor to open or close the valve in response to a wireless signal received by the transceiver. A handheld transceiver unit sends a signal to the actuator to open or close the cut-off valve, or operate in automatic mode.