The winterize valve selects the source from which the water pump draws fluid. In the "Normal" position, the water pump draws fluid from the fresh water tank. In the "Winterize" position, the water pump draws fluid from whatever fluid is presented, e.g. potable anti-freeze, into an umbilical hose that extends from the UDC. The umbilical hose is submersed into the fluid (anti-freeze) as a source for winterizing the RV plumbing. Each faucet is then opened in a singular pattern--using the water pump--to charge the plumbing with anti-freeze.