While you can do this yourself so long as you’re NOT using a manual pump from outside the rig, take my advice and recruit a helper. My wife and I usually tackle the winterization process together and it goes very smoothly.

1. Disconnect from any fresh water supply, if applicable.
2. Be sure all tanks are drained, including the fresh-water, gray-water, and black-water (body waste) tanks.
3. The water heater:

   — Most RV water heaters now come installed with a bypass valve or valves on the water lines that attach to the heater. This allows the water lines to be filled with RV antifreeze without having to fill the water heater as well, saving at least several gallons of antifreeze.

   — Turn the valve or valves into the bypass position.

   — Open the outside cover on the water heater compartment.

   — Remove the drain plug and open the temperature/pressure relief valve lever and let the water heater tank drain completely. A small amount of water will probably remain in the bottom of the tank, but it will have plenty of room to expand if it freezes and won’t hurt a thing.

   — Replace the drain plug.

4. Open all faucets in the rig.
5. Open the low-point drains. This will allow all the water to drain, even from the lowest points in the water piping within the RV.
6. Optional: Use air, if a compressor or an air tank is available, to thoroughly remove all water from the RV water lines. Most RV supply stores (such as Camping World) carry an adapter that screws into the fresh water supply fitting and that will accept an air nozzle (air chuck) like those used to inflate tires.
   Note: I have never blown my lines out with air, relying totally on thorough draining and carefully pumping antifreeze into the system. I’ve never had a problem (fingers crossed) and our New Hampshire winters can get pretty cold! However, many veteran RVers highly recommend blowing the lines out with compressed air and I respect their opinions and methods. It sure can’t hurt!
7. When the system is drained, close off the low point drains and all the faucets.
8. Now you’re ready to pump RV antifreeze into the water system. I’ve done this a couple of ways, and I started to do it a third way, but didn’t complete the process.

   — A fellow told me he’d had good luck pouring antifreeze into his fresh water tank and then simply using the 12 volt pump to fill the piping system. I decided to try it. It might have worked fine for him, but I discovered I’d have to use a lot more antifreeze than I thought, just to get enough in the tank so the pump would work. Maybe my tank was configured differently than his. At nearly $4:00 a gallon, I decided on a different method.

   — With another rig, I was able to easily attach a fitting with a plastic tube to the intake side of the 12 volt water pump. The tubing went into a full container of antifreeze and the pump was switched on. I was then able to use the pump to fill the water system with RV antifreeze. Starting with the low-point drain fittings under the RV, and then moving to the faucets farthest away from the pump, I opened them, one at a time, causing the pump to run and fill the line with antifreeze. When, at any given faucet, all the air is expelled and you get a steady stream of the pink antifreeze, shut the faucet off. The pump should stop running soon after you close the faucet.
   Note: The low-point drains usually terminate in a fitting that must be unscrewed with a wrench and are typically found under the RV. Their location varies from one rig to the next, but will normally be below part of the water system – under the bathroom, under the kitchen sink, etc.

   — Since I could easily unscrew the flexible shower hose from the tub faucet, I did that, drained it and left it hanging in the shower area. If your shower isn’t so easy to disconnect, you can obviously pump it full of antifreeze instead, or just drain the hose and shower head.

   — Another method is to use a hand pump. These are available from most RV supply outlets. They have an output hose that attaches easily to the outside fresh water connection where you normally hook into a campground water source. Then there’s an input hose that goes into a container of RV antifreeze. The only difference between this method and using the rig’s water pump is that you manually pump antifreeze into the RV water system. Your helper still opens one faucet at a time and tells you when to stop pumping.
   — Don’t forget the toilet! Press the flush lever or peddle until antifreeze flushes from the rim of the toilet. It won’t hurt to let a few cups of antifreeze run into the black-water tank.

9. The last step is to pour a cup or two of antifreeze into each of the sink drains and the bathtub drain to be sure there’s no water in the traps to freeze.

And that’s about it for winterizing the water system. You’ve drained and bypassed the water heater. You’ve thoroughly drained the water lines and filled them with antifreeze. You’ve filled the sink and tub or shower drain traps with antifreeze. You’re good! Nothing left to freeze.

In the spring, simply hook up to fresh water and flush out the lines by running water through all the faucets and the toilet until everything runs clear. Don’t forget the low-point drains. Then un-bypass the water heater and let it fill. I usually open the water heater drain and let it flush out a bit before buttoning it up and turning it on.

It’s a lot worse to write out the steps, or read them, than it is to do the job. It’s really a relatively simple process and goes quickly after you’ve done it once or twice.