Undetected water can cause thousands of dollars in damage. Protect your home from potential water damage by keeping a Leak Alarm anywhere flooding is a potential danger: aquariums, sinks, refrigerators, dishwashers, washing machines, water heaters, toilets, etc. These water detectors are powered by one 6F22 9V battery (included) and are equipped with a low battery indicator. When a water leak is detected, the unit will give off a very loud alarm (100DB).