To winterize with antifreeze you will need the following supplies and equipment:
Drain the fresh water tank. To find the drain, first locate the fresh water fill. The fresh water or portable water tank, as it is some times referred to, will be inside the trailer at the point of the fill. Some units have sub floor water tanks but they will be located by the water fill location. If your tank is inside your RV, the drain will be either at the base of the tank, (on the tank itself or at the end of a short plumbing line), on the outside of your RV below the water fill, or under the RV on a stanchion coming down through the floor. If your tank drains slowly, you may wish to look for waterline drain outs and speed up the process by opening the drains and turning on your water pump. Most pumps flow 3 gallons per minute, which means you can drain a 40 gallon tank in about 13 minutes.If the water tank in your units is in an insulated sub-floor, the drain will be located on the bottom of the tank under the RV. (*Note: some tank drains are routed out through the main frame of the RV and are hidden behind the wheels.)
Drain the water heater. First, turn off the 110V element in your water heater. To do this, switch the wall switch "and" the switch on the water heater itself to the off position. If you have a 1994 or newer unit, the on-off switch may be on the outside of the water heater, tucked under the control valve. You will find the drain plug or drain cock to be on the bottom of the tank inside the water heater access door on the outside of the RV. Using your 1/2 drive, remove the drain plug. The drain plug will either be plastic or metal. Be very careful to use the proper size socket because some drain plugs will be very tight. If your unit has a drain cock, it will look like a automobile radiator drain. Turn the drain clockwise to open. The pop-off valve is the brass valve at the top of the outside face of the water heater. Pull the pressure pop-off lever to a straight out position. This will relieve the vacuum in the water heater tank and allow it to drain.
Locate your low point drains if your RV is so equipped and open them. To find your low point drains, follow your plumbing lines through your unit. The drains will have pull up "T" valves if they are inside the RV. Some brands have low point drains outside, under the unit. These outside drains will be either 2-90 degree valves or 2 lines with caps or plugs. Next, open all sink and shower faucets in the RV This will allow most of the water in the system to drain.
After all lines have finished draining, turn on the water pump and run it for 5 minutes. This will clear out the fresh water tank-to-pump pickup line. Check to see if your water pump has a water pump filter screen mounted on the intake side of the pump. If it does, simply turn the screen housing counter clockwise to open. The purpose of this step is to drain the screen housing. After all the water is removed, reassemble the the pump screen housing. If your unit has a water filter, a winterize plug was provided at the time of purchase. Remove the filter and install the plug.
Disconnect the fresh water pickup hose from the water pump. (This is lead from the fresh water tank). Connect the 5' length of water hose to the pump where you just removed the water tank pick up line. Secure the 5' length with the same clap that was used on the original hose. Place the other end of the 5' length in one of your two gallons of antifreeze.
Switch the bypass valve on the water heater to the bypass position.
Turn on your water pump. Open each faucet in the RV and let the water run until it turns the pink color of the antifreeze. When you have finished this, reconnect the water hose to its original position and switch off the water heater bypass.
Connect your compressor to the city water inlet with the air to the hose adapter. Go through your RV and close all faucets and drains, leaving only the kitchen cold side open. (Hang a dampened wash rag or shop towel over the faucet to reduce water splattering). When all the water is blow out of that line, open the hot side of the kitchen faucet. Then with both hot and cold faucets open, close the cold side of that faucet. Repeat this procedure for the bathroom sink, the shower, the toilet valve and the outside shower if your unit has one. Always leave at least one faucet open so as to not build up excessive pressure in the water system. (On units with single mixer faucets, you can simply witch from cold to hot and no other faucet has to be open during that process. To aid in holding the valve open, simply open the flush valve and insert short piece of 2x2 directly into the flush opening. Let the valve close on the 2x2 and this will keep the water flush valve in the open position).
The last part of this step is to remove the water heater drain plug and blow out any water that may have collected in the bottom of the water heater. Also re-open the low point drains and make sure no water remains down in the stanchions. Finally, replace water heater and drain line caps and plug. (All drain plugs should be tightly in place).
To keep the sink drain traps from freezing, pour 3 cups of non-toxic RV antifreeze down each drain. Be sure to do all three; the kitchen sink, the bathroom sink, and the shower drain.Step #7Drain the holding tanks on your RV. If you have only limited contents in the tanks, it is not imperative that they be drained.
To de-winterize your RV, fill the fresh water tank and flush the water lines until the water runs clear.