I've been winterizing my trailer for over 10 years now, but I've always wondered about the black tank. Do any of you throw a few gallons of antifreeze down in your black tank to keep it moist during the winter, or do you just leave it dry? I have always put in 2 or 3 gallons to keep any remnants moist, but I wonder if it is really necessary.

I put enough RV anti-freeze in black tank to cover the dump valve. Then when toilet valve is closed pour a little over the top of it. I pour enough down the sink traps, shower traps etc. so enough goes down to cover the grey water dump valve. The anti-freeze keeps the valves moist so they don't dry out.

The MAIN thing to remember is to NEVER allow the black tank to completely dry out. No matter how well you flush it, there are always some solids left behind and these will turn to "stone" and become nearly impossible to remove (and they accumulate). Good luck / Skip

A few gallons of water left in the waste tanks will not cause you any problems. No freezing damage will occur as long as you don't start yanking on the valve handle while it's frozen solid. If it makes you feel better to spend money on extra antifreeze to throw in there, by all means do so.

I winterize with the pink stuff. However much pink stuff gets into the black tank while I am flushing out the toilet line and toilet sprayer, plus whatever overflows when I fill the P trap of the bathroom sink and flush the sink lines, which drains into the black tank, is all my black tank gets. Same with the gray tank. Whatever overflows from the kitchen P trap and the shower P trap is all the gray tank gets.That said, what does damage is ice expanding that has filled a line, breaking the line. As long as you drained the tanks so they are not full, when they freeze, there is room for the ice to expand without doing damage. It is far more important to be sure there is SOME fluid, even water, to keep the seals from drying out. If you drain the fresh tank, black tank, gray tank, and water heater you are good for winterizing those particular items. It is the water lines that you need to worry about.

I use a quickie flush in my grey and black tanks. I am 99.999999% sure I don't have any thing hanging on the walls or the bottom of the tank. over the year I have read about the proud owners of the flush kings and how good they are. if they are so good then why are the TT manufacturers putting quickie flushes in there TT;s and not flush kings? having said all that, I do put some pink in the black and the grey tank, probably about a qt., each. that is just for the seals to keep them moist. the grey tank gets it's share by way of the faucets and the "P" traps

Winterizing Black Tank? | Good Sam Community

15 Replies

Pauljdav
Explorer
Oct 10, 2013
I use windshield cleaner in my black tank to winterize. The winter formula. It will not freeze and it probably helps keep it clean.

I have not used the pink stuff because I blow out my lines. I pour the windshield fluid into all my P traps. I keep the grey tanks open so the extra drains to a bucket. I then pour the rest of the gallon into the black tanks.

I bet a great way to clean a black tank is several gallons of windshield fluid with a bag of ice added to it.

Paul

PS. Do not run windshield fluid through the fresh water lines.
Community Alumni
Oct 10, 2013
After the last dump, I throw in some deodorizer and about two gallons of water. I then throw in some pink anti-freeze via flushing.
wbwood
Explorer
Oct 10, 2013
Here's the way I look at it. You can usually get the RV antifreeze at Walmart for $3/gallon or at CW for less than $4.50/gallon. Unless you have a 45' DP or large RV like that, it normally does not take a lot to winterize an RV. I have no problem spending $15-20 on antifreeze. To me it's worth the insurance of not having to make a costly repair later. I feel better safer than sorry. When spring time is here, you remove it. Flush your lines several times and then sanitize it. Some claim that it lingers in their pipes and etc. In the 3 or 4 years we have been RVing, I've never had that issue. If we have a gallon or so left over (which we always do), it goes down into the gray and black tanks.
NebulaTig
Explorer
Oct 09, 2013
Fizz wrote:
Don't forget!
The low point on your black tank is the drain pipe.
Any water left in the tank means a full pipe.
Up here we get -30 every winter.
A sure pipe bust.

So what are you saying then? Dump your grey and black then come back with some anti-freeze?

Last year I just left my valves open with the cap loosely on with no problems, but this year I think I'm going to leave some anti freeze in.
bob2j8
Explorer
Oct 09, 2013
I just found some antifreeze on sale, so I decided that I will throw 3 gallons into the black just to make sure that everything stays moist over the winter.
wbwood
Explorer
Oct 09, 2013
I do put some antifreeze in the black tank. I'm no scientist and do not try to figure out what will freeze and to what extent. I normally buy several gallons of it and have some left over. It goes in the black tank. Never an issue. If it ain't broke, don't fix it.
jk31668
Explorer
Oct 08, 2013
i winterize with 5 gals of the pink stuff and then when all done i dump a gal of the blue washer fluid in the sink traps and toilet.
Fizz
Explorer
Oct 08, 2013
Don't forget!
The low point on your black tank is the drain pipe.
Any water left in the tank means a full pipe.
Up here we get -30 every winter.
A sure pipe bust.
Terryallan
Explorer II
Oct 08, 2013
Unless the black tank is dry when you pour in the pink. You are wasting your time, Water / whatever else, will dilute the pink to the useless point. I'm with Skip. I NEVER let my black tank go completely dry. I always put at least 5 gal, along with the treatment back in after cleaning. There is plenty of room in there for 5 gal of water to expand.

Mine don't even get anything from the sink drains, as on mine they drain into the grey. Does get a little from the tolite flush, and I cover the flush valve with pink.
herbhofmann
Explorer
Oct 08, 2013
How does the antifreeze interact with the enzymes for black water treatment?