Abstract: An anti-freeze apparatus for use with a recreational vehicle water system having a main water storage tank, a water pump, a hot water heater and domestic cold and hot water supply lines. The invention comprises an anti-freeze storage tank containing a supply of anti-freeze, a first valve mechanism in fluid communication with the anti-freeze storage tank and interposed between the water storage tank and the water pump and a second valve mechanism providing fluid communication between the water heater water inlet, the water heater hot water outlet and the domestic hot water line.