How to winterize a camper van water system (antifreeze vs blow-out)

Water systems November 4, 2026

Step-by-step winterizing for a camper van water system: draining, water heater bypass, a low-pressure blow-out and where RV antifreeze still matters, plus what owners report goes wrong.

To winterize a camper van water system, you get every drop of water out of the tank, pump, lines, water heater and fixtures, then protect whatever can still hold water. There are two ways to do it: blow the lines out with low-pressure compressed air, or pump RV antifreeze (the pink, non-toxic kind) through them. Most van owners do both: blow out first, then run a little antifreeze through the pump and fill every drain trap. Camco, which makes RV winterizing gear, says air pressure for a blow-out should never go above 50 PSI. Keep antifreeze out of the fresh tank and the water heater, and pour about a cup down each drain. If you're staying in the van through freezing weather instead of storing it, the goal changes: keep the plumbing inside the heated space or carry water in jugs.

This guide explains how to winterize a camper van water system step by step, when to use antifreeze vs a blow-out, and what owners report goes wrong. The steps suit typical DIY van builds (a freshwater jug or tank, a 12 V pump, PEX or hose lines, maybe a small water heater) as well as factory Class B vans. Always check your own water heater and pump manuals first, since some units have their own drain and freeze rules.

Why van water systems freeze so easily

Water expands as it freezes, and the American Red Cross notes that this expansion can break metal or plastic pipes no matter how strong they are. Vans are especially exposed: lines often run along uninsulated walls or under the floor, the fresh tank may hang under the chassis, and when the heater is off the cabin cools as fast as the outdoors. Pipes are rarely what fails first. Owners on the Class B Forum point out that PEX tubing usually survives a freeze, while plastic faucet cartridges, shower heads, pump strainer housings and other parts with small water-holding cavities crack. Ice also doesn't need extreme cold to do damage: a few nights just below freezing is enough.

Antifreeze vs blow-out: which to use

Method	How it works	Pros	Cons
Drain only	Open all drains and faucets and let gravity empty the system	Free, fast, no tools	Leaves water in low spots, the pump and fixtures; risky in a hard freeze
Compressed-air blow-out	Blow-out plug in the city water inlet or a tee, regulated air pushes water out of each outlet	No antifreeze in the lines; quick to de-winterize	Needs a compressor and regulator; pockets can remain in valves and the pump head
RV antifreeze fill	Pump propylene-glycol RV antifreeze through every line until it comes out of each tap	Protects water you can't blow out; good for quick winterizing on the road	Costs a gallon or two per season; must be flushed in spring; taste can linger if it gets into tanks
Blow-out plus a little antifreeze	Blow out first, then pump a small amount through the pump and into traps	Most thorough; uses little antifreeze	Takes the longest

Use only RV/marine antifreeze labeled for potable water systems, never automotive antifreeze. Choose a burst rating that suits your climate. Camco's guide mentions -50 °F and -100 °F products.

How to winterize a camper van water system, step by step

1. Prepare

Turn off the water pump and the water heater, and let a heater that has been running cool down.
Empty and clean the gray tank (and black tank, if you have one) at a dump station.
Take out anything that can freeze and burst: water bottles, filter cartridges, a countertop coffee maker, toiletries.

2. Drain everything you can

Drain the fresh tank through its drain valve, or remove portable jugs. Leave the drain open if the manual allows.
Bypass and drain the water heater. Camco calls this non-negotiable: set the bypass valves so antifreeze doesn't fill the heater, open the pressure-relief valve, then remove the drain plug or anode. Tankless and electric mini heaters vary; follow the maker's drain procedure.
Open low-point drains, then open every faucet (hot and cold) and the shower to let air in and water out.
Remove the pump's strainer bowl and run the pump for a few seconds to push water out of the head. Don't run it dry for long.
Take off fragile fixtures: shower heads, sprayers and inline filters. Store them inside your house.

3. Blow out the lines

Screw a blow-out plug into the city water inlet, or fit one to a tee or quick-connect at the pump outlet if your build has no city inlet.
Set the compressor regulator low. Camco's limit is 50 PSI maximum, and lower is safer for push-fit fittings. If your pump or fittings have a lower pressure rating, use that instead.
Open one outlet at a time, hot then cold, until it spits only air, then close it and move to the next. Include the outdoor shower and toilet if fitted. Go around twice.

4. Add antifreeze where it counts

Keep it out of the tanks. With the fresh tank and water heater isolated, use a pump converter kit (a tee and valve on the pump inlet) or a hand pump to draw antifreeze from the jug. Run each faucet until pink fluid appears.
Fill every drain trap. Camco suggests about a cup of antifreeze per sink and shower drain. Add some to the gray tank and to the toilet bowl or valve if you have one.
Leave things open or closed consistently. Note on a tag what you opened, so you don't fill the tank next spring with a faucet still open.

5. De-winterize in spring

Close the drains, reinstall the fixtures and the pump strainer, put the water heater back in line, fill the fresh tank with clean water, and run every faucet until it runs clear. Sanitize the fresh-water system per your tank or water heater manual before drinking from it.

Using the van in freezing weather instead

If you live in the van or take winter trips, a fully winterized system and a usable one are different things. Common approaches:

Move water inside. Keep the fresh tank and pump inside the heated cabin, not under the chassis. A Class B owner living at 8,000 ft reported adding a 10-gallon tank inside a closet for exactly this reason.
Carry jugs. Keep the plumbing winterized and use water jugs kept in the cabin. Add RV antifreeze to drains as you go.
Duct heat to the plumbing. Owners split a diesel heater duct to warm a water compartment or under-bed space. See the diesel heater install guide for safe placement.
Insulate exposed runs. Pipe sleeves and moving lines away from bare metal walls help, just as the Red Cross recommends for pipes in unheated areas at home. They only slow freezing, though; they don't stop it.
Watch the humidity. A heated van full of people and wet gear gets damp fast. See how to stop condensation in a camper van in winter.

If your batteries are lithium, cold affects charging too; see the van electrical system guide before a winter trip.

What owners report

On a long-running Class B Forum thread about cold-weather camping (posts from 2019 and 2020), one van owner described draining both tanks, blowing out the lines with compressed air, isolating the tanks, then pumping only a small amount of antifreeze through the lines and pump. The payoff was a quick spring flush with no antifreeze taste in the tanks. Another owner said a proper blow-out is enough on its own, as long as the pump's clear strainer cover and plastic shower heads come indoors and the traps get antifreeze.
In the same thread, a Minnesota owner said he relied on low-point drains, opened on the drive home, and stopped using antifreeze. Another Minnesota owner said he still adds antifreeze after blowing out when temperatures reach -20 °F, and finds it handy for quick winterizing while traveling.
One member reported a shower valve that cracked even after a compressed-air blow-out. Water had run back down the shower hose and settled in the valve, and the leak only showed up behind the wall the next time the shower was used (Class B Forum, page 3). Another left the faucets open over winter and forgot. The next spring, filling the tank sent water into a covered sink.
Owners who camp in winter in the same thread report using the van fully winterized down to about -20 °F, with bottled water and just enough RV antifreeze to keep the toilet valve and gray tank from freezing.
In a 2026 VW T6 Forum diesel heater thread, an owner described splitting the heater output into a switchable second duct that runs to the water compartment and bed for very cold nights.

Common mistakes

Forgetting the water heater bypass, which wastes gallons of antifreeze filling the heater tank.
Too much air pressure. Stay at or under 50 PSI, and lower if your fittings or pump are rated lower.
Leaving the pump strainer, shower head or filter housing in place. These are the parts that crack.
Skipping the drain traps. Trapped water can crack the P-trap or a gray tank valve.
Using automotive antifreeze. It's toxic. Only use potable-system RV antifreeze.
Assuming a mild climate is safe. Repeated freeze-thaw nights just below 32 °F cause plenty of damage.
Not writing down what you opened. A tag on the faucet or pump switch saves a flood in spring.

Bottom line

Drain everything, bypass and empty the water heater, blow out each outlet at no more than 50 PSI, then use a small amount of RV antifreeze in the pump and every drain trap. Bring the fragile plastic parts indoors. If you're using the van in winter, keep water inside the heated space or carry jugs, and treat the plumbing as winterized. When in doubt, follow your water heater's and pump's own instructions: they override any general guide.