A Drip pan is installed under your water heater. The WAGS valve is attached between the water source and the water heater. When leaking water fills the pan to a depth of 3/4", a water-soluble fiber element in the WAGS dissolves, releasing a powerful spring-loaded piston that closes the flow of water to the tank. In gas-fired water heaters, this action also breaks a fuse that shuts off the gas supply to the heater. This fiber-element technology was first used by the British Royal Air Force to inflate life jackets automatically. It's highly reliable, totally mechanical, and requires no additional power source.
