How to Winterize an RV: A Step-by-Step Guide (Antifreeze or Air)

If you are wondering how to winterize an RV before freezing weather, the job comes down to three things: get the water out of the tanks, lines and water heater, bypass the water heater, and then either fill the lines with non-toxic RV antifreeze or blow them out with compressed air. Camco’s winterizing guide lists 2 to 4 gallons of RV antifreeze for an RV with the water heater bypassed, and notes that the amount may vary.

Every RV’s plumbing is a little different, so keep your owner’s manual open while you work. As Winnebago puts it, “the instructions in your owner’s manual should be the final word on what you do.”

Before You Start

When to do it. Winterize before freezing temperatures arrive. Water left in the system can freeze and crack the lines or damage the water heater tank, Tiffin Motorhomes warns.

Pick a method.

• Antifreeze method: you push RV antifreeze through every line and fixture. It needs no compressor, only a pump conversion kit or a hand pump, and it is what Tiffin calls its “Preferred Method.”
• Blow-out method: you push the water out with compressed air, then add antifreeze to the drains, P-traps, toilet and tanks. Forest River’s version uses less antifreeze, but you need a compressor, a pressure regulator and a blow-out plug.

What you’ll need:

• Non-toxic RV antifreeze (propylene glycol or ethanol based) — never automotive antifreeze
• A water heater bypass (built in on many RVs; aftermarket kits exist)
• A water pump conversion kit to draw antifreeze with the onboard pump, or a hand pump (Camco’s guide shows both)
• Basic hand tools for the water heater drain plug or anode rod
• For the blow-out method: an oilless air compressor with a regulator and an air filter, plus a blow-out plug for the city water inlet
• Rags and gloves

How much RV antifreeze to buy. Quantities in manufacturer guides vary with the size of the RV and the method:

Bypassing the water heater saves a lot of antifreeze: Camco says “as much as 6 to 8 gallons” that would otherwise go into the tank.

How to Winterize an RV: Step by Step

The order below follows the procedures from Tiffin and Forest River. Camco’s guide handles the water heater differently (see the note in step 3). If your manual uses a different order, follow the manual.

1. Empty and rinse the holding tanks

Empty the black and gray tanks at an approved dump station, as Tiffin advises. The Unique Camping + Marine guide also has you deep-clean both tanks and rinse the black tank. Close the valves when you’re done.

2. Turn off the water heater and let it cool

Switch off both the electric element and the gas (LP) side of the water heater. Disconnect the city water hose and turn off the 12-volt water pump. Let the water heater cool completely — never drain it while it is hot or under pressure.

3. Open faucets and drain the fresh water system

Open every hot and cold faucet to release pressure. Then:

• drain the fresh water tank completely;
• open the low-point drains on the hot and cold lines, at the lowest points of the plumbing;
• once the water heater is cool, remove its drain plug or anode rod and open the pressure-relief valve (Tiffin’s order; Forest River sets the bypass first, then drains the heater).

Forest River’s manual also has you remove the cartridge from any water filter system and run the water pump “for at least 30 seconds to clear any water from the lines,” then switch it off. Camco says to bypass any in-line or undersink filtration systems.

4. Bypass the water heater

Turn the bypass valve (or valves) to the bypass position so water and antifreeze skip the water heater. Forest River notes that the valve sits near the heater’s incoming lines and that you may need to remove an access panel to reach it. Without a bypass, antifreeze fills the water heater tank — as much as 6 to 8 gallons, by Camco’s estimate.

5. Close the drains

Close the low-point drains and all faucets. Camco’s guide says to “leave open” the water heater drain for the winter, and Tiffin’s procedure does not put the plug or anode rod back in, so check your owner’s manual before you reinstall it.

6a. Antifreeze method: pump RV antifreeze through the lines

1. Connect the pump’s inlet to a jug of RV antifreeze with a water pump conversion kit, or use a hand pump from the outside.
2. Turn on the water pump.
3. Work from the highest fixture to the lowest, as Camco’s guide does: begin with the kitchen faucet, then typically the bathroom sink, shower, toilet and finally the outdoor shower.
4. At each faucet, Camco opens the hot side only until the flow “becomes very pink,” closes it, then repeats on the cold side. Forest River runs cold first, then hot; either way, both sides get antifreeze.
5. Flush the toilet until pink antifreeze appears in the bowl.
6. Replace the antifreeze jug with a new one as needed.

Don’t skip the “extras.” Tiffin’s procedure covers the washer, the ice maker or refrigerator water line and the exterior shower, plus antifreeze in the washer and dishwasher drains. Camco says to winterize the ice maker, washing machine and external shower according to their appliance manuals.

6b. Blow-out method: blow out the RV water lines

1. Attach the blow-out plug to the city water inlet.
2. Set the compressor regulator low. Forest River says “no greater than 30 lbs” (psi); Tiffin gives “30–50 PSI MAX”; Winnebago blows out at 35–50 psi and warns that “any higher may damage your plumbing.” Follow your own manual; where the guides differ, the lowest figure is the most cautious.
3. Open each faucet (hot and cold), the shower, the toilet valve and the outside sprayer until no more water comes out.
4. Disconnect the air and close all faucets and drains.

Forest River’s air method still finishes with antifreeze in the drains, P-traps, toilet and tanks, so go on to step 7.

7. Protect drains and traps

Pour RV antifreeze into every sink and shower drain to fill the P-traps — Tiffin says 1 to 2 cups per drain (toilet included), Camco at least 2 pints. Forest River’s antifreeze-only procedure also adds a gallon to the black tank through the toilet and a gallon down the sink drain that feeds each gray tank.

8. Prepare the rest of the RV for storage

• If you followed Camco’s order, open the water heater drain now, once the tank is cool, and leave it open.
• Leave the water heater and the water pump off; Forest River says not to start the water heater or use the plumbing after winterizing.
• Remove or disconnect the house batteries, or keep them on a maintenance charger (Tiffin).
• Cover the furnace, refrigerator and water heater vents with insect screens.
• Check tire pressure and seal the roof, as Tiffin’s storage list advises.

Antifreeze or Compressed Air: Which Method Is Better?

Camco’s guide combines the two: drain the system, blow out the remaining water with an oilless compressor, then add antifreeze. Blowing out is not required, Camco says, but “the remaining water will dilute your antifreeze,” and its -50 product “SHOULD NOT be diluted.” Tiffin also lists blowing out the lines as an optional step before its preferred antifreeze method. If your owner’s manual recommends one method, use that one.

Common Mistakes When Winterizing a Camper

If any step looks unfamiliar — especially working on the water heater or installing a bypass kit — a certified RV technician or service center can winterize the RV for you.

What to Do in Spring

De-winterizing is largely the reverse. Forest River’s manual says to “Flush and sanitize the water system prior to use”: drain the tanks, fill the fresh water tank, run the pump with the faucets open until the water runs clear, flush the toilet, dump the tanks again, sanitize the system and replace any water filter. Before using the water heater, close its drain if you left it open and turn the bypass valve back so the tank fills; only then turn the heater on.

Frequently Asked Questions