Watching the leaves change color usually means the camping season is drawing to a close. For many of us, it is a bittersweet time to park the rig and start planning for next year’s adventures.
If you leave water in your lines when the mercury drops, you are looking at a massive repair bill come springtime. Learning how to winterize a camper trailer is the single most important maintenance task you will perform to protect your investment.
In this guide, we will walk you through the professional methods for clearing your plumbing and prepping your trailer for the deep freeze. We will cover everything from the blowout method to using RV-specific antifreeze so you can rest easy all winter long.
Why Winterizing Your RV Is Non-Negotiable
Water expands by about nine percent when it turns into ice. In a confined space like a PEX line or a plastic faucet body, that expansion exerts thousands of pounds of pressure.
This pressure does not just cause leaks; it can literally shatter fittings and split water heaters down the middle. Replacing a hidden water line behind a shower wall is a nightmare that requires tearing out cabinetry and fiberglass.
By taking a few hours now, you avoid the “spring surprise” of a flooded cabin. Beyond the plumbing, winterizing also involves protecting your batteries and preventing mold or rodent infestations while the unit sits idle.
Essential Tools and Supplies for the Job
Before you start, you need to gather your gear. Having everything on hand makes the process go much faster and ensures you do not skip any critical steps.
- Non-toxic RV Antifreeze: Look for the pink stuff (propylene glycol). Never use automotive antifreeze (ethylene glycol), as it is highly toxic and will ruin your potable water system.
- Water Heater Bypass Kit: Most modern trailers have these installed, but older models may need a manual kit added.
- Blowout Plug: This is a small brass or plastic fitting that screws into your city water inlet.
- Air Compressor: A portable unit works fine, but ensure you can regulate the pressure.
- Basic Hand Tools: A socket set or a Crescent wrench is usually needed to remove the water heater drain plug.
- Tank Cleaning Wand: Useful for a final flush of the black tank before storage.
Step 1: Draining the Plumbing System Completely
The first goal is to get as much liquid water out of the trailer as possible. Start by taking your trailer to a dump station or using your home cleanout if legal in your area.
Drain your black tank first, followed by the gray tank to flush the hose. Once the holding tanks are empty, move to the fresh water tank and open the low-point drains.
Low-point drains are typically located underneath the trailer. They are the lowest part of the plumbing system and allow gravity to pull the water out of the lines. Open all interior faucets to break the vacuum and speed up the drainage.
Handling the Water Heater
Never drain the water heater while it is hot or under pressure. Turn off the electric and gas switches and let the water cool down completely before proceeding.
Open the pressure relief valve at the top of the tank. Use a socket to remove the drain plug or the anode rod located at the bottom of the exterior access panel.
Inspect the anode rod while it is out. If more than 75% of the sacrificial metal is eaten away, throw it out and buy a replacement for the spring to prevent tank corrosion.
how to winterize a camper trailer
When it comes to how to winterize a camper trailer, there are two primary schools of thought: the blowout method and the antifreeze method. Many pros actually combine both for maximum security.
The blowout method uses compressed air to force water out of the lines. It is “cleaner” because you don’t have to flush pink slush out of your system in the spring, but it can leave small pockets of water in valves if not done perfectly.
The antifreeze method involves pumping RV-specific fluid through every pipe. This is generally considered the gold standard for extreme cold because the antifreeze displaces every drop of water and protects seals from drying out.
The Blowout Method Procedure
Attach your blowout plug to the city water inlet. Connect your air compressor and set the regulator to no more than 30 PSI. Higher pressure can blow the fittings right off your PEX tubing.
Go inside and open one faucet at a time, starting with the one furthest from the inlet. Let the air push the water out until only mist or dry air comes through.
Don’t forget the toilet valve, the showerhead, and the outdoor kitchen or shower. Once every tap is dry, you can move on to the traps, but remember that air alone won’t protect your water pump or P-traps.
Step 2: Bypassing the Water Heater
If you choose to use antifreeze, you must bypass the water heater. If you don’t, you will waste six to ten gallons of antifreeze just filling up the heater tank before it ever reaches your faucets.
Locate the back of your water heater, usually hidden behind a panel or inside a cabinet. You will see a series of valves. Turn them so that the water is diverted away from the tank and flows directly from the cold line into the hot line.
This creates a “loop” that allows you to pump antifreeze through the hot water pipes without it entering the main heater tank. Ensure the tank is empty and the drain plug is left out or loosely threaded back in.
Step 3: Pumping RV Antifreeze Through the Lines
There are two ways to get antifreeze into the system. You can use a hand pump attached to the city water inlet, or you can use the trailer’s internal 12V water pump.
Most modern rigs have a “winterizing pick-up tube” near the water pump. You simply turn a valve, stick the clear tube into a gallon of pink antifreeze, and turn on the pump.
If you don’t have a pick-up tube, you can install a pump converter kit. This is a simple brass valve that stays permanently installed for easy winterizing every year.
The “Pink” Sequence
- Turn on the water pump and let the system pressurize.
- Start at the faucet closest to the pump. Open the cold side until pure pink fluid flows out.
- Repeat for the hot side. Note: The hot side will still be pink because of the bypass loop you created.
- Move to the next faucet and repeat. Do not forget the toilet and the outside shower.
- Flush the toilet until you see the pink fluid. This protects the flush valve and the seal.
Step 4: Protecting the P-Traps and Holding Tanks
Even if you used the blowout method, your P-traps (the U-shaped pipes under sinks) still contain water. If this water freezes, it will crack the plastic trap and leak into your cabinets.
Pour about two cups of RV antifreeze down every drain—kitchen sink, bathroom sink, and shower. This will displace the water in the trap and prevent it from freezing.
Finally, pour a small amount of antifreeze into the toilet bowl to keep the rubber seal lubricated. This prevents the seal from drying out and cracking, which would cause the bowl to lose its ability to hold water.
Ensure a small amount of antifreeze also reaches the gray and black tanks. This protects the waste gate valves from freezing shut or cracking during a deep freeze.
Step 5: Battery Maintenance and Electrical Care
Batteries are expensive, and a frozen battery is a dead battery. A fully charged battery will not freeze until the temperature hits roughly -70°F, but a discharged battery can freeze at 32°F.
If you are storing your trailer where you can keep it plugged into shore power, your on-board converter should keep the battery topped off. However, some older converters can “boil” a battery if left on all winter.
The safest bet for most DIYers is to remove the batteries entirely. Store them in a cool, dry place like a garage (not directly on concrete) and connect them to a battery tender or smart charger.
If you leave the batteries in the trailer, disconnect the negative terminal. This prevents “parasitic draws” from CO2 detectors or clocks from draining the battery over the winter months.
Step 6: Interior Protection and Pest Control
Plumbing isn’t the only thing at risk. Humidity and rodents can cause just as much damage. Mice love the insulation and wiring found in camper trailers.
Remove all food items from the trailer. This includes canned goods, which can freeze and burst, and dry goods like crackers that attract pests. Clean all surfaces to remove food scents.
Use moisture absorbers like DampRid to prevent mold and mildew growth. Place a few tubs throughout the trailer, especially in the bathroom and bedroom areas.
For rodent prevention, seal any gaps around plumbing or wiring with steel wool or spray foam. Some owners swear by dryer sheets or peppermint oil, but physical barriers are always more effective.
Step 7: Exterior Maintenance and Tire Care
Your tires are under constant load while the trailer sits. Over several months, this can cause flat-spotting or sidewall cracking, especially if the tires are exposed to UV rays.
Inflate your tires to the maximum PSI listed on the sidewall before storage. If possible, park the trailer on plywood or plastic mats rather than bare dirt or grass to prevent moisture from seeping into the rubber.
Invest in a set of tire covers. UV damage is the leading cause of premature tire failure in RVs. Covering them can add years to their lifespan.
Finally, check your roof seals and lap sealant. Use a dedicated RV roof cleaner and inspect for cracks. A small leak in November can lead to a massive rot problem by March.
Frequently Asked Questions About how to winterize a camper trailer
Can I use a shop vac to blow out my lines?
Generally, no. A shop vac provides high volume but very low pressure. It rarely has the “oomph” needed to push all the water out of the low spots in your plumbing. Stick to a regulated air compressor for the best results.
How much antifreeze do I need?
For most standard camper trailers, two to three gallons of RV antifreeze is sufficient. If you have a large fifth wheel with a washer/dryer or a residential refrigerator with an ice maker, you may need five gallons or more.
Is it hard to learn how to winterize a camper trailer on my own?
Not at all. Once you understand the layout of your water heater bypass and pump, the process is very logical. Most DIYers can complete the entire task in under an hour once they have the right supplies.
Do I really need to bypass the water heater?
Yes, absolutely. If you don’t, you are essentially trying to fill a 6-gallon tank with antifreeze before the fluid can reach your faucets. It is a waste of money and makes de-winterizing much harder in the spring.
What if I have an on-demand water heater?
Tankless or on-demand heaters have specific winterizing requirements. Most can be blown out with air, but you must check your owner’s manual. Some models have very sensitive internal components that require specific flow rates for antifreeze.
Closing Thoughts for the Off-Season
Taking the time to learn how to winterize a camper trailer properly is a rite of passage for any serious owner. It demonstrates that you value your gear and understand the mechanics of your home-on-wheels.
By following these steps—draining the tanks, bypassing the heater, and protecting the lines with pink antifreeze—you are ensuring that your first trip next spring will be about making memories, not fixing leaks.
Remember to keep a small log of what you did. Note where you stored the battery and where you put the water heater drain plug. This makes the “de-winterizing” process much smoother when the sun finally starts to shine again.
Stay safe, keep your rig dry, and we will see you back on the trails next season!
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