How to winterize a travel trailer: Keystone's antifreeze method, step by step

Water left in an RV's lines, tank or water heater can freeze and crack them, and Keystone's owner's manual is blunt about it: damage from the weather is not covered under warranty at any time. In northern Alberta that makes winterizing a fall job, not a someday job.

Keystone describes two methods. The compressed air (dry) method blows the water out with an air compressor. The RV antifreeze (wet) method fills the lines with RV-approved, non-toxic antifreeze. This guide covers the antifreeze method, which Keystone says takes about two hours if you do it yourself.

Disclosure: our High Level store sells Forest River and Kodiak travel trailers. These steps come from Keystone's own manual and owner guides, linked at the bottom. If you own another brand, follow your trailer's manual where it differs.

What you need

• RV non-toxic antifreeze. Keystone says 4 to 6 gallons with a water heater bypass installed. Without a bypass, you'll need an extra 6 to 10 gallons, because you'd be filling the water heater tank too.
• Never automotive antifreeze. Keystone warns it is poisonous and not for use in drinking-water systems.
• A screwdriver or screw gun, if you need to remove an access panel.
• A pump bypass hose, if your trailer doesn't have a winterizing port. Keystone says your RV dealer can supply the hose and fittings.

Step by step

1. Drain the water lines. Remove the low-point drain caps and open every faucet, including the outside shower if you have one.
2. Drain the fresh water tank and empty the grey and black holding tanks at an approved dump station.
3. Turn off the water heater on both gas and electric. Let the water cool, then drain it by removing the drain plug and opening the pressure relief valve. A tankless water heater has its own procedure in its operator's manual.
4. Blow out the black tank flush, if you have one. Keystone's manual says to use compressed air at no more than 30 psi, or pump antifreeze into the inlet with a hand pump.
5. Bypass the water heater. Turn the bypass valves to the bypass position. They're usually on the lines behind the water heater (you may need to remove an access panel) or in the water panel.
6. Take out the water filter cartridge, if you have one. Keystone says antifreeze should never be allowed into a water filter. Install the diverter or bypass tube if one came with the trailer.
7. Drain the ice maker line instead of filling it, if your trailer has a residential fridge. Keystone says not to put antifreeze in that line.
8. Close everything back up. Reinstall the low-point drain caps and close the faucets and the tank drain.
9. Hook up the antifreeze. Depending on your trailer, either turn the winterizing port valve and drop its hose into the jug, fit a bypass hose to the suction side of the pump, or, if you can't bypass the pump, pour antifreeze into the fresh tank above the pump's pickup level.
10. Pump it through every tap. Turn on the water pump. Open the cold side of each faucet, one at a time, until pink antifreeze comes out, then do the hot side. Don't forget the outside shower and any washer hookup.
11. Do the toilet. Flush until antifreeze reaches the bowl, then pour about a quart down to protect the black tank. Leave a little in the bowl to cover the seals.
12. Fill the p-traps. Pour about a quart of antifreeze down each sink, shower or tub drain. Keystone suggests wiping antifreeze off sinks, shower and toilet with a soft dry cloth to prevent staining.

Keystone notes the process can vary a little between brands and models because the plumbing differs, so check your own manual, and your water heater maker's instructions, before you start.

In spring: flush it out first

Keystone says a winterized system must be flushed and sanitized before you use it, and not to turn on the water heater while it's still winterized. Its de-winterizing steps:

1. Drain all tanks, then close the drains.
2. Fill the fresh tank with a garden hose.
3. Run the pump and open the cold side of every tap until the water runs clear, then the hot side.
4. Flush the toilet until the water in the bowl is clear.
5. Dump the tanks again.
6. Sanitize the water system.
7. If you have a water filter, drain the lines and put in a new cartridge.
8. Only then turn the bypass valve back to let water into the water heater, and fill it following its instructions.

Not sure about doing it yourself?

Keystone's manual says many owners have their dealer winterize the RV, and that your local dealer is best placed to answer questions about storage in your climate. Either way, it's worth reading our guide to matching an RV's weight to your tow vehicle before next season's first trip.