Abstract: In combination with a water piping arrangement having a backflow preventer and a water heater with a standard temperature-pressure relief valve, an auxiliary pressure-relief device is installed in the cold-water supply line to the water heater and this auxiliary relief device is adapted to activate at a pressure slightly below that which activates the temperature-pressure relief device, thereby releasing water and excessive pressure buildup in the piping arrangement due to thermal expansion of water in the water heater. The water released in order to prevent the excessive pressure buildup is routed to a floor drain via flexible plastic tubing.