First off, if you have a motion detector, make sure it is functioning properly. In short, walk in front of the detector. If it blinks, this means it was able to detect you. Important: if the battery of your motion detector is weak, the valve will close automatically after a 12-hour period. Therefore, if you notice the detector is not blinking when prompted, be sure to replace its battery. Secondly, press the OPEN button on the valve to turn the water back on.