A water leak detector is an electronic device that is designed to detect the presence of water for purposes such as to provide an alert in time to allow the prevention of water leakage. A common design is a small cable or device that lies flat on a floor and relies on the electrical conductivity of water to decrease the resistance across two contacts. The device then sounds an audible alarm together with providing onward signalling in the presence of enough water to bridge the contacts.

Water leak monitoring in buildings with sensitive electric and electronic equipment or valuables is today an elementary part of building supervision and guarding. The water leakage detection systems are used for the surveillance of rooms, piping and individual items. Each leakage is detected with metre accuracy and reported directly in the building surveillance. This ensures that the location of the leakage can be found quickly so that countermeasures can be introduced immediately. The sensor cable and point sensors can be combined at will. The monitoring electronics are available with or without locating. System calibration is not required. In addition, a line-break monitoring is integrated into each system.