How to Winterize a Travel Trailer

When to do it

Before the first hard freeze, not after it. A single overnight dip below freezing is enough to split a line if there is standing water in it. If you are unsure how much of the season is left, winterize early — there is no penalty for doing it too soon, and you can always de-winterize for a late trip.

What you need

• RV antifreeze — the pink, non-toxic, propylene glycol type sold for potable systems. Two to three gallons covers most trailers. Never use automotive antifreeze; it is toxic and must never enter a system you drink from.
• A water heater bypass kit if your trailer does not already have one fitted.
• A water pump conversion kit or a length of clear hose to draw antifreeze through the pump.
• A socket or wrench for the water heater drain plug, plus a screwdriver.
• A hose and somewhere the water can drain away.

The sequence

1. Drain the fresh water tank. Open its drain valve and let it empty completely.
2. Drain the water heater — but let it cool first, and release the pressure. Never pull the drain plug on a hot or pressurised heater. Turn it off, let it cool for several hours, open a hot tap to relieve pressure, then remove the plug or anode rod and let it drain.
3. Open the low point drains. Most trailers have two, one hot and one cold, under the floor. Open both, and open every tap inside — hot and cold, including the shower and any outside shower — so air can get in and water can get out.
4. Run the pump briefly to clear what remains, then switch it off promptly. Running a pump dry for long damages it.
5. Close all the drains and taps.
6. Bypass the water heater. This is the step that saves the most antifreeze — a heater holds six to ten gallons, and there is no reason to fill it with antifreeze. Set the bypass valves so water routes around the tank.
7. Draw antifreeze through the system. Fit the pump conversion kit or put the intake hose into a jug of antifreeze, switch the pump on, and open one tap at a time — starting with the closest and working to the furthest — until pink fluid runs steadily from each. Do the hot and cold side of every tap, the shower, the toilet flush and the outside shower.
8. Pour antifreeze into every drain trap. A cup or so down each sink and the shower drain fills the P-traps, which still hold water after everything else is empty.
9. Add antifreeze to the toilet bowl and the black tank after dumping and rinsing both waste tanks.

The steps people skip, and regret

• The water filter. Remove the cartridge. It holds water and antifreeze will not save it.
• The outside shower. Tucked in a hatch and forgotten every year.
• The washing machine or dishwasher if fitted.
• The icemaker line on trailers with a residential fridge.
• The city water inlet. There is a check valve behind it that can hold water.

While you are out there

Winter storage is the right moment for the jobs that prevent bigger bills. Inspect the roof and reseal any cracked sealant around vents, skylights and the front and rear caps — water intrusion ends more trailers than anything mechanical. Remove all food. Leave cabinets and the fridge propped open so they do not grow mould. Take the battery out, or at least disconnect it, and keep it charged somewhere above freezing; a flat battery left in the cold is usually a dead battery by spring.

Cover the tyres or move the trailer occasionally to avoid flat spots, and take the weight off the tyres if it will sit for many months. Block off entry points where mice get in — around the underbelly, and where wiring and plumbing pass through the floor. Steel wool in the gaps works better than traps do afterwards.

De-winterizing in spring

Reverse the process: restore the water heater bypass to normal, refit the drain plug and the water filter, flush the antifreeze out through every tap until the water runs clear, then sanitise the fresh water system before you drink from it. Refill and pressurise while you are still at home, and walk the trailer inside and underneath looking for drips. Finding a leak on your own driveway is much better than finding it at a campsite.

Frequently asked questions

Can I just blow the lines out with air instead?

Compressed air is a legitimate method and many owners use it, at low pressure — typically around 30 to 40 psi, never shop-line pressure. Many people do both: blow the lines out, then add antifreeze to the traps. Air alone leaves nothing protecting the P-traps.

How much antifreeze do I need?

Two to three gallons is typical with the water heater bypassed. Without the bypass you will use far more filling a tank that did not need it.

Do I need to winterize if I store it indoors?

In a genuinely heated space, no. In an unheated barn or garage, yes — those spaces follow the outside temperature closely.

What if I skipped it and it froze?

Do not pressurise the system to find out. Let everything thaw fully, then refill slowly and inspect every visible line and fitting while watching for drips, including inside cabinets and under the bed where lines often run.

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