Wednesday, February 8, 2023


Keeping RV water lines from freezing during cold winter use

Dear Gary,
We have a Class C motorhome. We have used it quite often this winter and have resisted winterizing it because we use the shower and toilet and such. I have heated it through the winter so far without any problems, but during a recent cold snap the bathroom plumbing froze. I believe the problem is where the water lines run under the floor to the opposite side of the cabin. Interior heat, I suspect, was not enough to keep the lines from freezing under the floor.

To thaw the lines, I am using a bullet heater under the motorhome outside to try and get the floor temperature above 32 degrees. In the living area I have added a ceramic heater and fan and have opened all the drawers to get heat back into the recesses of the bathroom. So far I have been able to unfreeze the hot water line, but not the cold water line yet. What can I do to keep this from happening again? I cannot find any diagrams telling me exactly where the water lines run under the coach. Is my only solution to winterize those lines? —David

Dear David,
Winter RVing is indeed enjoyable — especially if the family is into the snow toys and/or slope activities. But, as you say, it can be difficult if the plumbing succumbs to below-freezing temps.

snowI would be surprised if the water lines truly are routed via the exterior under the coach. Typically they will route in and through cabinets or in voids through the walls and maybe under the top flooring. Some coaches, however, are better insulated than others, so it could be an insulation issue. If you can trace the lines, it may be possible to wrap them each in foam-type insulated jacket available at most home supply centers. There is also heat tape that can be wrapped around them in those areas prone to freezing. Accessibility is the key, however.

If you didn’t need water for the shower, another option would be to blow the fresh water lines clear of all moisture and simply use bottled water for flushing the toilet.

Also remember, running water is less likely to freeze. If possible, when you are connected to a dump assembly in a campground, for instance, leave the gray tank valve open and the cold water seeping just a little through the bathroom faucet. The gray water will continually drain and this will minimize the chances of the cold line freezing. All this advice from a guy who spent all but the last few years living in Florida and Southern California! But it may help. Other than that, winterization is the only other viable option when the coach is not in use.



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Thomas R Sloan/ Alice M Sloan
3 years ago

On the response to leave a water tap running into the gray drain hose to prevent freezing of water lines. Please DON”T!! The water going through the gray drain will freeze, eventually building ice up all the way back to the drain inside. Then you will have water running over in the sink or shower drain! It will ruin your carpet, cabinets etc.!!! Just leave drawers, cabinet or closet doors open. Use Ceramic heaters to assist in concentrating heat where water lines are located. Or use heat tape, Carefully, to keep those water lines above freezing temperatures! Many times, if lines are barely froze, a warmed towel on them does the trick. Having spent 40 years in the RV Repair business, have seen several RV’s flooded, resulting in expensive repairs due to leaving water dripping in freezing temperatures!

Richard Schroeder
3 years ago

Living in MN we have been winterizing our class A motorhome each winter. However, now we are considering spending part of the winter in the south so I need some advice.
If the RV is winterized (no water in the tanks), do we drive it south until we reach warm enough temperatures to drain out the antifreeze in the lines and then add water?
And what about on the return trip if MN still has freezing temperatures when we return? Drain the water before we drive home again? Thanks

Peggy Phillips
3 years ago

When I was going south for just February, I winterized my class A and used gallon bottles of tap water from home to flush the toilet and for drinking. I drained the antifreeze when I arrived in south Texas, and used the city water connection. I didn’t fill my water tank. I winterized before leaving for home at the end of February, and used the gallon water jugs for the return trip. Now, since I’ve retired, I just leave MN at the end of October and plan my return so its warm enough for the pipes not to freeze!

theresa brown
4 years ago

Our class C did the crazy last year when we neglected to do a basic winterize – end result – spring rolled around and we went to turn the water on and the kitchen faucet literally blew right off the top of the sink – turns out, not only did the lines freeze but it also damaged the water pressure regulator – after replacing sink faucet and pressure regulator, we also found the lines sprung a leak at the shower area so we finally had to take in the RV for the nice rv repair folks down the road to replace the shower lines – all good after that, this year, taking no chances – blew out the lines, drained the hot water heater and fresh water tank, and added RV antifreeze in all the drains, so now, soon as the mood hits to take off somewhere, it should be easy peazy

4 years ago

Identical problem, simple solution.
If temps are below freezing operate from your freshwater tank but do not leave the on-demand water pump energized. When needed to flush a toilet etc, turn the pump on, use the water, turn the pump off and drain the waterlines from faucet furthest from the pump (ie:kitchen hot water faucet) and leave the faucet open. Water can’t freeze if line is empty! With next use, turn pump on first, then shut off the faucet to expell air. If any ice has formed from remnant of moisture in the line, the slightly warmer freshwater from the tank will thaw as the line fills and repressures the line. You won’t waste more than a couple of cups of water and your plumbing remains unharmed.

Bob C.
4 years ago

Re: RVDoctor suggestion to leave water running to prevent freezing lines. That can work in a house but not in an RV. Under below freezing conditions, the “running” water will freeze in the stinky slinky and plug it in no time.

4 years ago

Like Barry, I too used the slow trickle method with the same results. The rear kitchen sink drained the length of the trailer. The long expanse of drain line was exposed and froze, filling the line, the galley gray tank, backed up to the sink, then onto the kitchen and living room. Stepping barefoot into freezing cold water at 3am was not a good way to start my day. So before using the trickle method, trace where that water will go!

4 years ago

We spent four winters in our Outdoor RV Timber Ridge (one of the Nash family – as is Arctic Fox). One winter saw temperatures down to minus-22 C/minus-8 F (yep, we’re Canadian and were in Canada). That same winter brought six weeks of continuous below freezing weather – day and night.

Just so you know, we did not put skirting around the trailer and did not use RV anti-freeze.

We were the only rig in the park that did not have humidity problems – like water running down the inside walls or freezing on the inside of the windows. We used the installed propane furnace – using a 30-pound/7-gallon tank every four days – and one 1500 Watt electric heater and kept the ceiling vent in the shower open a little. The humidity inside our trailer was a steady 40%. Our propane and electricity bills ran about $200 a month less than the other rigs in the park. And we were the only rig that didn’t have significant running water problems.

We were hooked up to city water using a plug-in electrically-heated water hose. Any outside freezing we experienced was at the standpipe. Then I would take a heat gun to it for about 30 seconds. At about minus-11 C (outside) our water line running from city water connection (by the bathroom) to the hot water heater (by the kitchen) – i.e., opposite ends of the trailer – would freeze. We still had cold water in the toilet because that was at the point where the city water entered the rig. At minus-7 C (outside) our lines would all thaw.

To help the inside heat get to the water lines I removed the access panels – e.g. under the shower, under the sinks, enclosing the water pump.

The fresh water tank was at the other end of the trailer near the kitchen and hot water heater. We (almost) always had hot and cold water in the kitchen – as long as I had water in the tank. On occasion, the fill pipe for the fresh water tank would freeze. My mistake was filling the fresh water tank until water came out of the filler. As long as the tank was not completely full and the filler pipe was dry, no freezing there. The tank itself was heated.

As for sewer, we made use of the park facilities for showers and relied on our holding tanks to last long enough that I could get a warm(er) spell to dump. We kept the valves closed except when dumping. For sure I couldn’t wait for above-freezing temperatures but the contents of the holding tanks stayed liquid and dumping full tanks was done quickly. We experienced some pyramiding but cleared it in the Spring.

My point is this: If you are going to spend a cold winter in an RV, buy one that has been built for winter use.

4 years ago

I used the faucet drip method once. Gray valve was open and drain hose was in sewer pipe.
Drain hose froze solid, backed up water into the gray tank and overflowed the shower.
Took a couple of days below freezing, but not the best long term solution.

Al Wegleitner
6 years ago

I have used a 60watt Flood light installed in a cheap metal flexible desk lamp that I place in the fresh water tank bay and leave plugged in while we are hooked up – works well and have not had any frozen pipes or water tank/ pump issues down to -30 F so far.

Gregory Illes
6 years ago

With the aid of Winnebago’s excellent chassis drawings, I identified where the water lines are routed. I then installed a low-draw circulation fan to flow a small amount of air from the cabin, through the inner walls and floor spaces.

Now, using the efficient catalytic heater, I keep the cabin at 45-50F or so, and the circulation fan keeps the air in the ducts from getting below freezing. This solution even works when boondocking.

Randy Hoepfl
6 years ago

We solved the freezing problem by adding a hybrid electric heating system called the Cheap Heat system. With this system we can heat our RV all year by keeping it plugged in.

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