If you’re reading this article in November, time may remain. Pump your RV’s veins full of antifreeze, and you may stave off the worst of the effects of the cold. 

But if you’re reading this March, then the prognosis is poor. If you forgot to winterize your RV, and Christmas Bells have already stopped ringing, then whatever damage was going to happen, has.

So if you have forgotten to winterize your RV, what should you expect?

Unfortunately, the answer isn’t reassuring. As an RV Technician, I always expect to receive several calls in the spring from frustrated, damp customers who are dealing with broken outdoor showers, leaky city water inlets, busted water heater tanks, and soaking subfloors. Sometimes they merely forgot; sometimes, they didn’t care. Sometimes they purchased a used RV that was too-good-to-be-true.

I remember one used travel trailer, in particular, that my customer had recently purchased as his full-time mobile home. The previous skunky owner had lied about the condition of the plumbing, and the camper obviously hadn’t been winterized in years. Over the course of three visits, we wound up replacing every single faucet and fixture in the RV, plus a good bit of the supply lines. It was a game of water whack-a-mole.

What Temperature Should I Winterize My RV?

It may not be too late! Yes, water freezes at 32 degrees, but not instantly. Heat transfer takes time. If the thermometer dipped to 31 degrees at night while you were out camping during Halloween, you likely have nothing to worry about. A little dew frost on the grass doesn’t mean your pipes are about to bust.

In meteorology, a “hard freeze” is defined when the temperature drops to 28 degrees or below and lingers there for at least an hour, usually several. This same danger zone for plants is the same danger zone for your RV. When the thermometer drops to 25-28 degrees for several hours, your RV’s water supply may be in danger of freezing. 

Note that we’re talking about ambient temperature, not wind chill. PEX pipes don’t care about wind chill, and unlike, say, the metal hood of your vehicle, they don’t face an infinite heat sink (the sky) to radiate massive heat loss. 

It’s Not Pipes That Burst – It’s the Fittings!

There are several myths and misconceptions around RV winterizing. The first is that all water, no matter what or wear, poses risk.

That is not quite true. Water inside a storage tank, whether fresh or waste, rarely poses danger. Most RV water storage tanks have plenty of space and flexibility for water to freeze and expand.

In the same way, the fear that your “pipes will burst” if your RV freezes is actually a bit of a misnomer. Modern RVs use PEX (mostly PEX-B) and braided PVC vinyl hoses for the water supply lines. These materials can expand significantly before cracking – and remember, water expands about 9% by volume when it freezes. And the PVC or ABS pipes used for the drain system don’t have any standing water (expect for the traps, where water has room to expand).

There is a BIG exception to this claim – and that’s the polybutylene pipe that was the darling of the RV and residential construction industries back in the ‘80s. Unfortunately, after a $950 million settlement for a claim for premature product failure, PB pipe has lost its luster. A friend of mine summed it up pretty well: “After 20 years, that stuff turns to dust when you touch it.”

As an RV technician, I rarely see pipes, tubing, or hoses busted by frozen water pressure. Instead, I’ve seen fittings burst, cracked, and split. Fittings are typically made of brass, nylon, or poly (a shorthand term for many types of rigid plastic). Unlike pipe or tube, they can’t expand. They don’t bend; they break.

Age can worsen the brittleness of plumbing fittings. Brass can dezincify, leaving it porous and brittle. Poly fittings become frangible with chemical degradation (and the cold makes it worse). If you forget to winterize your classic 1986 Beaver Motorhome, be prepared for serious damage.

What If I Didn’t Winterize My RV – What Will Break?

If you didn’t winterize your camper with antifreeze or compressed air and you’re concerned about damage, here’s what might be damaged:

• Black tank flush: This fitting is often forgotten! Thankfully, it usually doesn’t hold water, but it’s best not to test your luck. 
• Kitchen and bathroom faucets: The delicate plastic or brass parts in the valves inside a faucet are easily damaged by freezing expansion. If you’re lucky, you can just replace the stem and bonnet hardware or cartridge valve instead of the entire faucet.

• Outdoor shower: I’ve seen many of these units fail. Most RV outdoor showers are really, really shoddy. They don’t stand up too much, particularly the mounting NPS-threaded shafts on the back.
• Toilet water valve: I can count on several of these calls every spring. Someone forgets to run antifreeze through the toilet, and the water valve on the back of the flush sports a hairline crack, which sometimes only shows up when the pedal is flushed. 
• City water inlet: There’s a one-way valve inside a city water inlet that requires tight clearances. If the fitting is damaged, the city water inlet will often leak. Don’t try to MacGyver a solution – just replace the entire inlet.

• Sewer gate valve: If the RV dump tanks are used during freezing weather and not insulated or heated, then the first thing to go is usually the dump valve. If this is a cable-actuated valve, then the cost to replace can be several hundred dollars.
• The water pump: One of the reasons I often winterize with antifreeze through the RV pump is that the antifreeze protects the innards of the pump as well.
• Water heater: If you didn’t drain your RV’s water heater, then it’s quite likely cracked. Hairline cracks in mixing chambers or water tanks often don’t show up until the tank is heated. Unfortunately, this is a very expensive repair. Replacing a tank in a conventional RV water heater or the mixing chamber of a tankless RV water heater is often almost as expensive as replacing the entire unit, which is anywhere from $500 to $1,500 just for parts.

Obviously, any part of your RV’s water system can be damaged by frozen water, but these are some of the most common areas I see.

How Can I Find Leaks In My RV Water’s System?

The only method to know for sure that you have a leak-free water system is to have it pressure-tested, which is far beyond the scope of this article.

Some leaks announce themselves as geysers that flood your floor, but others quietly hide in the shadows, rotting your subfloor drip by drop. The smallest leaks often cause the most damage, as they cannot be seen, only their handiwork. 

At a minimum, you need to perform the following inspections. I recommend using a water pressure of 60-65 psi to find leaks. While your RV is theoretically rated by code for 80 psi (sometimes more), anything above 65 psi is what I consider the informal “danger zone.” For regular use, I recommend 40-55 psi, which is the preset pressure for most RV water regulators and on-demand water pumps. 

• Check the floor area around your water heater for stains, sponginess, and wetness.
• Inspect the supply lines for all faucets and showerheads. Try it with the water running and stopping. Faucets may also leak from the body seat, close to the deck.
• Flush your toilet and watch the toilet water valve for any leaks while the pedal is open or closed.

Some of these inspections may require you to remove access panels and even crawl inside your camper. 

I often recommend customers do what I call “The Poor Man’s Leak Test.” Disconnect from city water and fill your freshwater tank with several gallons of water. Ensure it is working properly. Next, close all your faucets and fixtures. The pump should run to build up pressure, and then stop. Set your timer. Wait 10-20 minutes. If the pump cycles within that time frame, then you either have a water leak, or the pump is damaged and is allowing short-cycling. 

If that sounds like a lot of work (and potentially expensive), then yes, it is. So don’t forget to winterize your RV’s water system!