Wednesday, February 8, 2023


How to use your RV toilet in cold weather

Chris Dougherty, Certified RV Technician, posted this tip while he was serving as’s technical editor.

Some people prefer not to use the plumbing system during the winter for fear of doing something wrong and risking a freeze-up, and subsequent damage. Others prefer to just use the toilet, and depend on campgrounds for their other needs. It’s possible to use your RV toilet for brief periods in freezing weather.

Purchasing a four-season RV or modifying one to handle sub-freezing weather is one possibility. I have done this previously with good success. This requires a coach with completely enclosed and heated holding tanks.

I prefer to add individual tank heaters and a separate heater for the utility compartment. I have also added digital freeze alarms to those areas to make sure that the temperature doesn’t dip too low in vulnerable areas. Work off the holding tanks only, and dump when necessary. Don’t stay connected to outside utilities.

But what if your RV isn’t winter-capable? Here’s the no-water option: It may be possible to use the RV toilet without the use of water, but extreme care must be taken to prevent freezing and damage. The process involves using potable RV antifreeze instead of water to flush the toilet. Starting with a completely empty black water tank, add at least 3-4 gallons of RV antifreeze to the black tank, and continue to use the RV antifreeze to flush the toilet as necessary. When you’re done using the system, dump as usual, then there should be no freezing problem.

For you snowbirds out there, using the coach’s water system from the cold temperatures to the warm and vice-versa is an option, but I wouldn’t recommend doing so unless you’re certain that your enclosed tanks are protected well enough for the climate. An option is to use the system as pointed out above, keeping the heat in the coach on, using minimal water, and making sure there’s adequate antifreeze in the holding tanks. Many folks will start using the system in the Mid-Atlantic region, for instance, headed south, and will re-winterize there on the way back.

Whichever you decide to do, make certain that the toilet is well winterized when you are done. Small amounts of water can remain in the flush valve on some toilet models, which can freeze and crack the valve if not completely removed or replaced with antifreeze.



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Marc Journault
2 years ago

Using RV toilet in winter? Even if the black tank is not frozen, I don’t know where you can dump when the stations are under a layer of ice hard like rock or under two meters of snow.
2 years ago
Reply to  Marc Journault

In places like Oregon where lots of areas freeze overnight but thaw during the day. interesting idea I might try this winter!

J anne
2 years ago

I flush with pink antifreeze by not using toilet water or pump to flush. Just pour it in each time. That way only concern is tank and it takes time to freeze anyway due to mass of liquid. My tank small 10 gal in class b. I have spent repeated nights and days as low as 9 degrees and no problems. Also if tank not full there is room for expansion even if freezing starts. Been working for 15 years and I I travel every winter . I dont look for freezing temps but often find.

Tina McK
2 years ago

That can be expensive! I have used windshield washer fluid! A lot cheaper and does the job!

2 years ago

I use a thermocouple outlet and two low watt heat lamps with shields. One in the grey/black compartment, one in the freshwater. On at 35d, off at 45d. Yes, you do need to be plugged in.

2 years ago

Aren’t you concerned with dumping antifreeze or other chemicals into the sewer or septic system of the dump station? I’m a fan of water quality, so would probably find some other way to handle the problem.

2 years ago
Reply to  Chris

 PROPYLENE GLYCOL – This type of antifreeze is only available in RV shops. It is non-toxic and the safest for all types of RV plumbing. This antifreeze is non-flammable and does not taint water systems. Propylene glycol is a lubricant and will actually work to extend the life of the seals in your toilets and faucets.
I know that automotive antifreeze is quite toxic and can be deadly for many living things. Found this but, I do not know how completely RV antifreeze is “non toxic” and “does not taint water systems”, but it must not be too bad, especially if it is dumped into a dump station. I agree on maintaining water quality.

Tommy Molnar
2 years ago
Reply to  Lago

My understanding about RV “anti-freeze” is that it DOES freeze, but unlike water, does not expand and that’s the difference. Am I wrong?

2 years ago
Reply to  Tommy Molnar

I have found -50f Rv anti-freeze frozen and we only had about -38f! I was very concerned about that. Now I find at Menard’s and Walmart they have -75f Rv anti-freeze. (?) So, anyone have an answer to Tommy’s question? I have not had any damage to grey pipe plumbing, tanks, toilet valve etc.. (We winterize our cars with -34f automotive anti-freeze!

Also, after applying anti-freeze to the holding tanks, I remove the “P” traps and leave them in the sinks. Simple task. Be SURE to plug the line with a rag or cap from the holding tank!!! (Stay safe, wear a mask and drive with care!)

2 years ago
Reply to  Chris

Propylene glycol is used as a sweetener in some food items, it is safe for consumption.

2 years ago

Thirty gallon plastic kitchen bag lining the bowl, throw in some cat litter, dispose of properly.

2 years ago
Reply to  Cletus

That’s what I was doing to but saw this video and am going to try it. Will still dispose of daily but cheaper than kitty litter.

2 years ago
  1. I also use windshield washer fluid, sometimes its cheaper and easy to find, make sure its for cold enough, ck jug for temp rating some are for summer only. I use it at my cabin to winterize the wash machine and all the toilets, P traps etc.
2 years ago
Reply to  Frank

Try using de icing salt,the same stuff you would use on side walks in the holding tanks,works great!
I have a winter season of experience with this in Whistler B.C ,not coldest in temps but can see-20c .
Salt water doesn’t freeze easily.
Very cheap alternative .
Cost is about 10$ for 20lb
Ad 3 or 4lb to empty tank with water

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