I live in North Idaho. My winterizing procedure is drain the all tanks: grey and black, fresh water and water heater. Turn on water heater bypass. I have made a fitting to hook up my air compressor to the city fresh water hookup. I blow out all lines with air including the toilet. With the drain on the water heater still unplugged, I open the coldwater line to the water heater blow out some residual water in the heater, although the heater manual states, about two quarts will remain in the heater and is OK for the winter. Close the heater line again and run the water pump to get any remaining water out of the pump. Run air through all faucets, and do not forget the outdoor shower. I had PC install shut-offs inside the coach for the outdoor shower as we sometimes use our coach in the winter, so after the outside shower is blown out we close the shut-offs and do not have to worry about that area freezing. After everything is blown out, I add RV antifreeze to all the drains(p-traps), and do not forget the shower drain and toilet. I pour about half a gallon into the shower drain and then open the gate valve on the grey tank so it goes to the sani-con pump, run it momentarily to protect it, then close the gate valve. There is enough anti-freeze in the systems to protect the gate valves, especially if you use your unit in the winter. Nothing like going to dump and finding your gate valves frozen shut. Another thought is you may find RV antifreeze expensive, so an option is windshield washer antifreeze fluid. Our local dealers use it exclusively, but do not use it in your freshwater lines. After they are blown out there is no reason to run antifreeze through empty lines. I use about 50 PSI air to blow out the lines. One thing I was surprised about was the lack of a sacrificial anode in the water heater. Without one, in most cases the electric heating element becomes the sacrificial anode. My first RV water heater without one. Just my thoughts.
Bob
