I know there is a lot of info here about winterizing. However, i have a specific question I can't find answer to. I just winterized my TT. We still had about 4-5 gallons of water in the black water tank (as you all know, to keep it from going dry and having things harden). Since our last trip of the season won't pan out, I just put 1 gallon of RV antifreeze in the BW tank. (besides all the regular winterizing activities..so this question is about the BW tank only). Will this suffice in the BW tank or should it be empty for winter, or ???Appreciate the info...shouldn't be hard question but it's stumping me right now.

IMO diluting the antifreeze five to one with the water already in the tank would make the freeze protection ineffective. Can't prove that as I always give the black tank a good flush after the last trip until clear water with only a few flakes of TP comes out, then drain it as much as possible. No worries about freeze damage is there is only a little water left in the bottom of the tank.

Get a five gallon bucket and drain it just put a cloths pin on you nose. :E

As stated above a diluted mixture won't give much in the way of protection. I always completely drain mine then add a gallon of AF split 1/3 - 2/3 between black & grey tanks.

For your black tank. Remember water expands when it freezes. So ask yourself. Will 5 gal in a 40 gal tank expand enough to fill over fill the tank with ice? Answer. NO. so flush is as normal, and leave the 5 gal in it to prevent the dreaded black tank dry syndrome. And don't worry any more about it. I have always left 5 gal in the black tank. No problems. There is plenty of room for expansion.

Terryallan wrote:Remember water expands when it freezes. So ask yourself. Will 5 gal in a 40 gal tank expand enough to fill over fill the tank with water? Answer. NO. The tank's not the issue, it's large and flexible. The 4" rigid drain pipe at the bottom of the tank and the drain valve however will burst with only a quart of water in there.

RV antifreeze in BW tank | Good Sam Community

28 Replies

Bumpyroad
Explorer
Oct 11, 2014
Big_Blue wrote:
My experiment for this winter. I'm going to leave a half gallon of RV antifreeze (in the original jug) on the back deck & monitor the solution state & temperature.

Stay Tuned.

don't quite understand what you are trying to accomplish. I took some 2 year old/ opened container cheap stuff antifreeze and diluted it 1/3 water and put it in my freezer overnight and it just slushed up like it is supposed to. I predict that unless it drops to minus 50 (or 20) degrees that it will only slush up. My opened and unopened bottles spend several winters in an unheated garage. and I predict the temperature will sort of reflect air temperatures with a much slower swing in them.
bumpy
Big_Blue
Explorer
Oct 11, 2014
My experiment for this winter. I'm going to leave a half gallon of RV antifreeze (in the original jug) on the back deck & monitor the solution state & temperature.

Stay Tuned.
TechWriter
Explorer
Oct 11, 2014
mleekamp wrote:

I just winterized my TT. We still had about 4-5 gallons of water in the black water tank . . . I just put 1 gallon of RV antifreeze in the BW tank.

Will this suffice in the BW tank or should it be empty for winter, or ???

I'm with those who suggest completely draining your black tank before storage.

However, I'd suggest nuking your tank with a strong bleach solution before draining. It'll be easier on your nose and will also sanitize your tank. Also, bleach is much more economical than "cheap vodka".

I'm not sure what the "dreaded black tank dry syndrome" is, but myself and others drain the black and gray tanks completely -- and leave the black & gray gate valves open. (Use a sewer vent cap if you're worried about critters getting into your tanks.)
pkunk
Explorer
Oct 11, 2014
Water in your waste drain piping in below freezing temps is guaranteed to break something. It is not necessary to leave anything in your waste tanks in the winter. I blow my lines, run the pink, then blow out the pink. You'd be amazed at how diluted the pink is, and it will still leave a clog of slush that takes a day with heat on before I can fill with water, flush lines and hit the road in winter. Don't take chances, use the pink stuff.
wbwood
Explorer
Oct 06, 2014
Bumpy. It was meant to say they stand behind it 100%. I was going to have them do it where they just blow out the lines and put antifreeze in the traps. But hey had stopped doing it that way. They still blow out the lines, but they also run antifreeze through the lines. They said they can only guarantee it that way.
Bumpyroad
Explorer
Oct 06, 2014
wbwood wrote:
Terryallan wrote:
For your black tank. Remember water expands when it freezes. So ask yourself. Will 5 gal in a 40 gal tank expand enough to fill over fill the tank with ice? Answer. NO. so flush is as normal, and leave the 5 gal in it to prevent the dreaded black tank dry syndrome. And don't worry any more about it. I have always left 5 gal in the black tank. No problems. There is plenty of room for expansion.

Was told the same thing by our dealer who winterized ours last year. They stand behind winterizing it 100%.

would anybody pay a firm to winterize their RV with only a 90% chance of it being adequate? well we think it will work?
bumpy
wbwood
Explorer
Oct 06, 2014
Terryallan wrote:
For your black tank. Remember water expands when it freezes. So ask yourself. Will 5 gal in a 40 gal tank expand enough to fill over fill the tank with ice? Answer. NO. so flush is as normal, and leave the 5 gal in it to prevent the dreaded black tank dry syndrome. And don't worry any more about it. I have always left 5 gal in the black tank. No problems. There is plenty of room for expansion.

Was told the same thing by our dealer who winterized ours last year. They stand behind winterizing it 100%.
mlts22
Explorer II
Oct 06, 2014
The strange thing is that I emptied about 1-2 ounces of Dawn dish detergent and a bottle of cheap vodka into my BW tank when I winterized it... even in the mid-teens of last winter, I had no cracks or issues with the black tank.

I personally winterize with cheap vodka... but it is cheaper than RV antifreeze where I live.
JaxDad
Explorer III
Oct 06, 2014
shadows4 wrote:
If you don't want to drain just put another gallon of anti freeze in. I think it would be fine. Might be able to use window washer fluid in it would be cheaper. JMHO

NEVER use windshield washer fluid for freeze protection. They use alcohol in it because it evapourates quickly, so quickly that on cold days or at highway speeds it will leave the water behind as coloured slush.

If you pour it in the BW tank, the alcohol will rapidly evaporate leaving you with straight water!
Bumpyroad
Explorer
Oct 06, 2014
JaxDad wrote:
Bumpyroad wrote:
JaxDad wrote:
As stated above a diluted mixture won't give much in the way of protection.

I always completely drain mine then add a gallon of AF split 1/3 - 2/3 between black & grey tanks.

in another thread I posted my results where I diluted some antifreeze with 1/3 water and it just slushed up as it was supposed to do.
bumpy

At, or to, what temperature?

I suspect it gets a little colder in IL than in VA.

this was in my freezer at home overnight. I made no claims that it was a scientific study, just myth busted a post that "any dilution will render it useless". and the AF I use is rated to -50 degrees, not -20 so it has a bit of an advantage there. if it is only good to -25 after dilution, its OK.
bumpy