Economical way to defend against water leaks in multiple locations throughout the home Detects water 116 deep Ideal for use in areas not usually observed Water heaters behind washing machines or dishwashers under refrigerator for ice makers under sinks sump pumps of inside pits toilets behind or near media systems Provides early warning of potentially costly water damage Alarm sounds for up to 24 hours dependent upon battery life Low battery chirp Requires 9V battery sold separately.