How to Winterize an RV: Plumbing, Antifreeze and Storage Steps

Learning how to winterize an RV properly is a rite of passage with a sharp edge: water left in a line, a pump or a water heater expands as it freezes and splits fittings that cost far more to repair than the hour the job takes. Winterising is mostly about the plumbing, but a complete job also prepares the engine, batteries, tires and interior for months of sitting. This guide walks the full routine in order — drain, bypass, protect — using the two methods manufacturers publish, so the rig wakes up in spring with everything working.

When to Winterize, and What You Need

Winterise before the first hard freeze — sustained temperatures below freezing, roughly 28°F (−2°C) or colder for several hours, are what burst plumbing, and a single night can do it. Supplies are modest:

Non-toxic RV antifreeze (propylene glycol, rated for potable systems) — typically 2–3 gallons for the antifreeze method. Never automotive antifreeze; it is poisonous.
A water pump converter kit or a short length of hose to draw antifreeze from the jug.
A water heater bypass — most modern RVs have one fitted; older rigs may need a kit.
A blow-out plug and a pressure-regulated air supply if you use compressed air.
Basic hand tools, a bucket, and an hour or two.

DIY materials typically run roughly $15–$40 as of October 2026, mostly the antifreeze; a dealer or mobile tech doing the same job commonly charges roughly $100–$250 depending on rig complexity.

Step 1: Drain Everything

Turn off the water heater (gas and electric) and let it cool; relieve pressure before opening anything.
Drain the fresh-water tank and open the low-point drains to empty the hot and cold lines.
Open every tap — kitchen, bathroom, shower, outside shower — to break the vacuum and let the system empty.
Drain and flush the water heater by removing its drain plug or anode rod. Flush sediment out with a rinse wand; it is also your annual chance to see how much anode rod is left.
Flush the toilet to drain its valve, run the water pump briefly to clear it, then switch it off. Empty and rinse the grey and black tanks at a dump point and leave the waste valves closed afterwards.

Step 2: Bypass the Water Heater

This step protects your wallet, not the plumbing: an un-bypassed water heater fills with antifreeze first — 6 to 10 gallons of it — and its tank residue taints the system. Turn the bypass valves so the heater is isolated from the lines. If your rig has no bypass, fit a kit; it pays for itself the first winter.

Step 3: Protect the Lines — Pick Your Method

Compressed air method: fit the blow-out plug to the city-water inlet, set the compressor regulator to no more than about 30–40 psi (higher can damage fittings), and open taps one at a time until each runs air, not water — hot and cold, every fixture, the toilet valve and the outside shower. Remove or bypass any in-line water filter, which would trap water. Air alone leaves the traps and pump unprotected, so pour a cup or two of RV antifreeze into every drain and the toilet bowl afterwards.

Antifreeze method: with the water heater bypassed and the system drained, draw antifreeze with the pump (converter kit or a hose in the jug) and open taps one at a time, nearest first, until pink runs from each — hot and cold sides, shower, outside shower, toilet (flush until pink). Run any ice maker or washing machine per its maker's instructions, or have a tech handle those appliances; they hold water in valves and pumps that the simple routine misses.

Many owners do both: blow out first, then pump antifreeze through — belt and braces for very cold climates. Finish by pouring antifreeze into each sink and shower trap and the toilet bowl (it keeps the bowl seal wet), and check the pump strainer bowl is emptied.

The spots everyone forgets: the outside shower (a short hose run that freezes first), the black-tank flush inlet and its vacuum breaker, the in-line water filter housing (remove the cartridge and empty the sump), the city-water inlet screen washer pocket, and the low-point drain caps themselves, which trap a mouthful of water each. Any one of them can split quietly and announce itself as a spring leak — walk the rig with a list, not from memory.

Step 4: The Rest of the Rig

Engine and generator (motorhomes): fill the fuel tank to limit condensation, add fuel stabiliser, and run the engine and generator long enough to circulate treated fuel into every line. Change engine oil before storage if it is near due — used oil sitting all winter is harder on bearings than clean oil.
Batteries: charge fully, top up flooded cells with distilled water before charging, and either remove the batteries to a cool, dry place on a smart maintainer or leave them in place disconnected with a maintainer attached. A discharged lead-acid battery can freeze and split; a charged one tolerates deep cold.
Tires: inflate to the manufacturer's recommended pressure, park on plywood or plastic pads rather than bare concrete or soil, and fit covers — months of UV and a flat spot are both avoidable.
Interior: remove all food (including cans and dry goods — they attract rodents and can freeze), prop the refrigerator doors open after a thorough clean, add moisture absorbers, close blinds on the sunny side, and leave cabinets open for airflow.
Exterior and pests: seal obvious entry points around plumbing and wiring penetrations, remove nests from the fridge and furnace vents and cap them with insect screens, and give the roof one last inspection — storage is when roof leaks do their quiet work, so pair this with the routine in our RV roof maintenance guide.

Storing It: Covered, Level and Breathing

A breathable RV cover protects against UV and debris while letting moisture escape; a tarpaulin does the opposite and can trap condensation against the finish, so avoid tarps. Park as level as you reasonably can, chock the wheels, and settle the rig securely per your storage facility's rules. If the rig is stored where deep cold meets shoulder seasons, remember the people who skip winterising entirely are the ones who use their rig all winter — our guide to living in an RV in winter covers the heated-hose, skirting and insulation route instead.

Spring: The Job in Reverse

Winterising only proves itself at de-winterising, so finish the story now. In spring: close the drains, return the water heater valves from bypass, refit its drain plug or anode, and flush the antifreeze out with fresh water until every tap runs clear. Then sanitise the whole system with the standard dilute-bleach treatment, flush again, and pressurise the plumbing while you walk the rig checking every fitting you touched in autumn — a weep found in the driveway is a washer; the same weep found at a campsite is a holiday problem. Refit a fresh water filter, test the water heater on both sources, and only then call the season open.

Finding Help

Short on time or tools, or storing a motorhome with residential appliances? A one-off winterisation is a routine service call, and you can find dealers, service centres and mobile technicians through the RV Frontier provider directory. Done in autumn, the whole routine is an afternoon; done by spring's first freeze warning, it is a repair bill. Winterise on your schedule, not the weather's.