Winterizing Your Travel Trailer Plumbing
Updated: 1 day ago
One hard freeze with water in the lines can split a PEX fitting, crack a faucet body, or ruin a water heater or pump. On an Airstream, a lot of the plumbing runs behind curved interior panels and under the floor, so a freeze repair is rarely quick. Winterizing is mostly about getting water out and, if you choose, putting RV antifreeze in its place. Plan on an hour or two the first time. It gets faster once you know where your trailer's drains and valves are.
Plumbing layouts vary a lot by model and year, and especially by water heater type. Read the winterizing section of your owner's manual and the water heater manual first, and use this guide as the overall sequence.
Choose Your Method
Blowing out the lines with compressed air leaves almost no water behind and nothing to flush in spring, but small amounts can remain in low spots, valves, and the pump. Pumping non-toxic RV antifreeze through every line protects those low spots but takes several gallons and a spring flush. Many owners do both: drain, blow out, then run antifreeze through and into the traps. If your trailer will see deep, sustained cold, the combination is the safest bet.
What You Need
Non-toxic RV and marine antifreeze, often two to three gallons for a mid-size trailer. Never use automotive antifreeze in a potable water system.
A water pump winterizing kit or siphon hose if your trailer does not have a built-in winterizing valve, or a hand pump for the city water inlet.
For the air method: a blowout plug adapter for the city water inlet and an air compressor with a regulator.
The tools your water heater requires for draining, plus a bucket, towels, and a flashlight.
Step-by-Step Winterizing
Dump and flush the holding tanks. Empty and rinse the black and gray tanks at a dump station so they go into storage as clean as possible.
Remove water filters. Take out any inline or whole-trailer filter cartridges and bypass the housings. Antifreeze and freezing water will damage the cartridges.
Shut down and drain the water heater. Turn off the electric and gas modes and let the water cool completely. Relieve pressure by briefly opening the pressure relief valve, then drain using the method your heater requires. Tank-style heaters typically have a drain plug or anode rod; tankless units such as Truma models have their own drain and winterizing steps that you must follow from the manual. Draining a hot or pressurized heater can scald you.
Bypass the water heater. If your trailer has bypass valves, set them to bypass so you are not filling a tank-style heater with gallons of antifreeze. Some tankless systems do not use a bypass and instead require draining only.
Drain the fresh tank and the low-point drains. Open the fresh tank drain and the hot and cold low-point drains. Open every faucet, including the shower and any outside shower, and turn on the water pump briefly to push water out, then turn it off as soon as it runs dry. Running a pump dry for long can damage it.
Blow out the lines (optional but recommended). Close the low-point drains, thread the blowout plug into the city water inlet, and set the compressor regulator to a low pressure. Many RV manufacturers suggest staying at or below about 40 to 50 psi to protect fittings. Open one faucet at a time, hot then cold, until only air comes out, then close it and move to the next. Flush the toilet with air until it sputters. Finish by opening the low-point drains again to release what collected.
Pump antifreeze through the system. Close all drains and faucets. Set the winterizing valve or install the siphon kit so the pump draws from the antifreeze jug, not the fresh tank. Turn on the pump. Starting at the faucet closest to the pump and working outward, open the cold side until bright pink antifreeze runs steadily, then the hot side, then close it. Do the same at the shower, outside shower, and any ice maker or washer line. Flush the toilet until antifreeze appears in the bowl.
Protect the city water inlet. Antifreeze from the pump does not always reach the inlet check valve. Push a little through from the outside with a hand pump, or depress the check valve with a screwdriver until antifreeze shows, then cap it.
Fill the traps and tanks. Pour about a cup of antifreeze into each sink and shower drain to protect the P-traps, and a quart or so into the toilet and gray tank to protect the dump valves and seals.
Shut it down. Turn off the pump, switch the winterizing valve back, leave the water heater drained and bypassed, and label the faucet or water heater switch so no one powers up the heater dry next spring.
Easy-to-Miss Spots
Outside shower and any exterior wash station.
Black tank flush inlet. Blow it out with air or follow the manual; it is often a separate line with its own check valve.
Pump strainer and the pump head itself.
Washer, dishwasher, or ice maker connections on models that have them. Follow the appliance manual.
De-Winterizing in Spring
Close the drains, take the water heater out of bypass, reinstall the drain plug or anode and filters, and fill the fresh tank. Run every faucet until the water runs clear and the pink is gone, then keep going a bit longer. Fill the water heater completely, with a hot faucet open until water flows steadily, before you turn on the electric or gas mode. Then sanitize the fresh water system; our fresh water tank sanitizing guide walks through it. Check under sinks and at the water heater for drips during the first fill.
Do it the same way every fall, keep a list of your trailer's specific drains and valves taped inside a cabinet, and winterizing turns into a calm afternoon instead of a spring surprise.
Recommended gear
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