By Andrew Herrick
As an RV technician, I get asked about RV winterization a lot. Personally, I’m a fan of winterizing with liquid antifreeze through the onboard water pump. Where I live, winter packs an MMA-level punch, so I trust the pink stuff to get the job done.
These are the most common RV winterization mistakes I hear about when I help my customers winterize. If you read this list first, you might avoid a future visit from me!
7 common RV winterization mistakes
1. Not writing down your custom winterizing checklist
The first step to winterizing your RV is to read your Owner’s Manual, and slowly, sadly realize that it’s an ambiguous, poorly written instructible that doesn’t actually apply to your floorplan. You’re pretty much on your own.
So whip out a pen or tablet, analog or digital, whichever you prefer, and write down your own winterizing checklist. Most of us have the RAM of a 1980s Macintosh, so trust your checklist to remember the important steps.
2. Pouring antifreeze into the freshwater tank
While there’s nothing technically wrong with this practice, it’s an error most RVers only make once. After you pour antifreeze into your freshwater tank, it’s dad-gum impossible to get the taste out.
This is because most RV freshwater tanks actually don’t drain all the way. Outlets are often spin-welded on the sides of the tank, not the bottom, so it’s difficult to completely empty the reservoir.
In the spring, it can take a half-dozen or more fill-and-drain cycles to dilute the liquid in the tank enough to remove the taste of antifreeze (with subtle notes of cough syrup and acid mine drainage). You’re better off pumping antifreeze into everywhere but your freshwater tank. Just drain the tank and leave it alone.
3. Forgetting your outside water inlets and outlets
Everyone remembers to winterize their interior fixtures: faucets, showerhead, toilet, toilet wand sprayer, etc. You remembered to do both HOT and COLD sides, right? Remember, you’re not just protecting the PEX lines and fittings, you’re also protecting the delicate valves inside your fixtures.
But what about your exterior fixtures? Your outdoor shower, low-point drains, and city water inlet? Forgetting the city water inlet is a classic mistake when you winterize through your onboard water pump, but you can purchase a $5 blowout plug that allows you to properly pump antifreeze through your water inlet.
Don’t neglect this one! I’ve seen sidewalls delaminated and rotted beyond repair because the city water inlet froze, broke, and leaked into the sidewall structure.
4. Not bypassing your water heater
Again, this is a classic RVer 101 oversight. If you’re wondering why your RV just guzzled 10 gallons of antifreeze, it’s because most of it went into your water heater! Conventional RV water heaters have 6- or 10-gallon tanks. Again, while antifreeze doesn’t harm the water heater, it’s a waste of antifreeze and very difficult to get the taste out. So best to bypass and drain your water heater (through drain plug or anode rod) for the off-season.
How do you bypass your water heater, you ask? Hehe … If only there was a one-size-fits-all answer to that! Give me a Sharpie, and I can draw a dozen different ways your RV manufacturer may have plumbed the water heater bypass, depending on whether you have a water management system (e.g., Nautilus), water heater check valves, 3-way diverter or simple 2-way shut-off valves, etc. Best to refer to your Owner’s Manual and cross your fingers that they included an illustration.
5. Bypassing your (tankless) water heater
Did I just say that not bypassing your water heater was a mistake? Well, like everything in the RV world, there are exceptions! If you have a tankless water heater (also known as an instant or on-demand water heater), then the opposite rule may apply! Tankless water heaters actually do have a small reservoir (er, tank?) of water inside, and they don’t easily drain via gravity. So most tankless water heaters require you to run antifreeze through them to properly winterize.
6. Not bypassing your water filter
Many RVs now have water filters. These filters ain’t too smart. They’ll do their darndest to clean out the antifreeze, which will typically ruin the filter element.
If you’re lucky, your water filter was installed with a diverter bypass system, which allows you to drain and bypass the water filter entirely with a simple lever. If not, then just remove the water filter, clean and dry it, store it inside a Ziploc bag for the winter, and allow antifreeze to fill up the empty housing. You’ll use an extra 1/3 gallon or so.
7. Forgetting the sewer P-traps
If you have waterless (e.g., HepvO) traps, you’re exempt from this requirement. For the rest of us, you need to pour 1-2 cups of antifreeze down each sink and shower drain to winterize the P-trap. This prevents regular water in the traps from icing up or evaporating, which would allow sewer gases to infiltrate your RV interior. Ensure you have a little pink stuff in your toilet bowl, too. It’s not necessary to keep any water or antifreeze in your waste tanks, but a little antifreeze won’t hurt.
(Bonus) RV winterization mistake: Using automotive antifreeze
Thankfully, I’ve never dealt with this boo-boo firsthand, but I’ve heard horror stories about this worst of the common RV winterization mistakes.
You see, most RV/marine antifreeze is made from propylene glycol, a common ingredient in dough strengtheners and food thickeners. It’s food-grade. You can eat it, but it doesn’t taste very good! Automotive antifreeze, on the other hand, is usually made from ethylene glycol, which is highly toxic. Just two tablespoons ingested can kill a small child.
If you accidentally poured automotive antifreeze into your system, DO NOT USE IT. You will need to have the system commercially cleaned and tested. This is even beyond the scope of most mobile RV service technicians; we don’t have the testing equipment. So don’t make this mistake!
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RVDT2801
IMO, if you are not storing in long deep freeze conditions (like below 20F for several months), blowing out the lines & fixtures with low pressure (<40psi) air and using RV antifreeze in just the traps, toilet and a little at the waste tank valves works just fine. And know that the cheaper -50F antifreeze is usually ethanol based and a bit harder on the toilet & tank rubber seals than the more expensive propylene glycol based (often rated for -20F).
There is also a process when you choose air over antifreeze in your lines. However, air is much faster when you want to de-winterize.
(another tip follows below)
Another tip regardless which winterization technique you use: If your low-point drain lines use the caps, replace them with ball valves. You will need a PEX cinch tool – Amazon has inexpensive kits, but you can also borrow or rent one for this 10 minute job.
I also suggest putting the valve close to the RV belly and insulating between the valve and belly. Ice starts to form at the bottom of the filled and exposed PEX line and then proceeds into the belly. So why fill the line all the way out to that exposed cap? Ditch the caps, put the ball valves near the belly, add some insulation. Fewer freeze issues if you use your RV in cold weather, and much easier to drain your water lines.
Two corrections. A blow out plug does not allow you to put A/F in the water inlet without using some sort of pump and adapters. The easiest way is to press the check valve in the inlet while the onboard pump is pulling the A/F. Just cover the inlet with a rag so you don’t get sprayed.
Or use a hand pump. They connect directly to the inlet and pull the A/F from the gallon jug.
Also use this for the black tank flush inlet.
As far as PG antifreeze, it is getting harder to find and much more expensive.
Most readily available A/F is ethyl alcohol based.
Also don’t forget the ice maker and water dispenser if you have a residential fridge.
Thank you for the information and warnings, Andrew! Our climate may be closer to Florida’s than yours, so we use our RV through the winter (daily highs in the 40s, or higher) and have avoided this task. However, this is very helpful in case I do have to winterize in the future. Have a great week, safe travels, and a merry Christmas!