Anti-freeze ratio

Use your heat, not AF. Terrible idea to put it in the FW tank.

dougrainer wrote:
I have never heard of this or been asked the question in 40 years as a Tech.

And he's been on here 14 years.

The only time you use RV antifreeze is when you winterize for winter storage.
To continue to use the RV during the winter, heat and insulation is used

Bobbo wrote:
It should be 100% water, or 100% antifreeze, or empty. Your choice.

Disagree - there's never any reason to introduce RV antifreeze into any fresh water holding tank, ever. When not in use during the cold weather months it should simply be drained of any residual water and left like that, as should the water heater tank, any water remaining will have plenty of room to expand as it freezes and not cause any issues at all.

chast wrote:
Hey All—traveling to the great frozen Northeast in our B-van and expect temps in the 20’s at night. Would like to continue to use the fresh water system and want to add RV antifreeze to the tank. What do you think a safe ratio would be to prevent freezing the outside tank and lines? The tank is 35 gallons.

What year/make/model of B van is it, if I may ask? Some B vans are better suited for withstanding cold temps. What does your owner's manual say about camping in freezing temps?

Anecdotally,
Our 2002 Roadtrek was pretty good at handling freezing temps for short periods overnight. The plumbing was Pex, lines and joints, which had a little room for expansion if the water started to freeze/expand. We usually just tried to keep the inside of the van heated overnight as best we could, opened cupboards to allow some warmer air to reach the plumbing where possible, ran the W/H to keep the tank from freezing, and put some RV A/F in the black/gray tanks via the usual access points (toilet, galley sink). In 9 years of occasional sub freezing temps, we never had a problem.
If the overnight temps start regularly getting below the low 20s Farenheit, with the daytime temps close to freeze, you might want to consider doing a quick blow out winterize of the fresh water system. If your fresh tank is external to the coach interior, I would drain it. Then use bottled water for your fresh water needs.
Good luck with it.

chast wrote:
Sorry for confusion guys! We would like to continue to be able to use the fresh water and drainage systems when the temps are freezing at night and OK during the day. We NEVER drink the water from the tanks and the water would only be used for dishes, showers and toilet. So, how much antifreeze do I need to add to 35 gallons (the non-toxic RV type) to achieve this?

Well the RV anti-freeze, doesn't really stop the freezing, it will freeze to a slush, and NOT expand so fitting are not damaged.
You would likely be better off just using bottled water.

RV antifreeze is slippery and smelly. It is meant to be used full strength, diluting it makes it less effective.

I would not use water that contained antifreeze for any purpose.

It should be 100% water, or 100% antifreeze, or empty. Your choice.

Depending on the construction of your RV
Fresh water with 20's at night you may not need do anything to the fresh water system. PROVIDED you have heated tanks.. You can also get tank heaters that peal and stick on the tank if you wish or in my case since the tanks are enclosed and there is room I slipped a string of incandescent C-9 (9 watt lamps) Christmas lights under the tank.. They put out about 300 watts. and a 100 watt rough service lamp in the valve bay (Caged so it can not touch anything and melt it) NOTE 15 watt lamps will melt plastic 9's do not.

But I have all enclosed plumbing..

Water heater.. Either drain and bypass it. or leave it on and hot (hot water will NOT freeze so long as the heater is heating.

chast wrote:
Sorry for confusion guys! We would like to continue to be able to use the fresh water and drainage systems when the temps are freezing at night and OK during the day. We NEVER drink the water from the tanks and the water would only be used for dishes, showers and toilet. So, how much antifreeze do I need to add to 35 gallons (the non-toxic RV type) to achieve this?

If you're saying you want to add RV anti freeze to your fresh water tank and use that mixture for washing dishes and showering I sure wouldn't. :E

I have never heard of this or been asked the question in 40 years as a Tech. BUT, RV Antifreeze does NOT have a texture and consistency like water. It is kind of "slimy". I would NOT want to wash or do dishes with a mixture of water and antifreeze. NOT dangerous, just something I would think may result in a bad thing. Using it for the toilet system would be OK. Doug