Tuesday, June 6, 2023


Bottled water for RV toilet use — and more winter RVing tips


gary-736Dear Gary,
We are newbies at this, and it’s our first winter. If we winterize our 5th wheel and then want to go camping in the winter, is it safe to use the black tank with bottled water only? Since the black tank hoses appear to be quite large it’s hard to believe they would freeze. Or are there smaller hoses somewhere in the black tank system that we can’t see that could freeze? We would be using bottled water only for any fresh water needs, so we wouldn’t disturb the antifreeze in the rest of the system. Is our thinking right on this? —Barb H. 

Dear Barb,
plumbwaste8It is perfectly doable to use the black tank with bottled water if you choose that route. It’s also possible to use the complete fresh water system in the coach during the winter with some proper preparation. See my winter RVing article here. But typically it’s a full 3-inch drain from the toilet into the solid waste holding tank so just pouring bottled water into the toilet before and after each flush, you should be fine. I’d add a little RV antifreeze to the bottom of the holding tank just to keep it from freezing if you’ll be in extended below-freezing weather. And remember, you’re in an RV so you can always head south!




Read more from Gary Bunzer at the RVdoctor.com. See Gary’s videos about RV repair and maintenance.



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6 years ago

Gary’s probably got more experience with RV pipes, but I have to disagree with black lines being just fine with bottled water… Most toilets drop straight into the tank, but there is ALWAYS a section of pipe under the tank and before the valve. It doesn’t matter how big the line is, because freezing a lake still moves boulders. While septic contents have a different freeze point, they still freeze when cold enough, and CAN rupture tank and drain line. Consider how cold it really is, how exposed your tank and lines are and whether you have a heated tank, how often you’re flushing new warm contents, and decide your own risk. Near freezing with six people flushing is fine, alone at -10 is not. Also remember, even without damaged pipes, large ice blocks don’t dump…

J. Medeiros
6 years ago

Worried about freezing use window washer fluid if your on the road,
it’s treated so it won’t freeze and isn’t that expensive.

Tommy Molnar
6 years ago

I’m going to assume these folks are NOT using expensive bottled water (which, in most cases, costs more than gasoline!). I guess the idea is to not use the on-board water tank, which I also don’t understand. You’re either going ‘camping’ or you’re not. But, who am I to say???

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