A Water detector is a small electronic device that is designed to detect the presence of water and alert humans in time to allow the prevention of water damage. A common design is a small device that lays flat on a floor and relies on the electrical conductivity of water to decrease the resistance across two contacts. A 9 volt battery then sounds an audible alarm in the presence of enough water to bridge the contacts. These are useful in a normally occupied area near any appliance that has the potential to leak water, such as a washing machine, refrigerator with icemaker, dehumidifier, air conditioner, or water heater.