Black Water Tank Winterizing

[LarrySharon]

It looks like I am not going to get to move my trailer before winter sets in. If the black water holding tank has a bit of material in it and you pour in gallon or two antifreeze would that be OK? Normally all is MT but might not be able to.

[RKamperRV]

You can use antifreeze or...

Once I used 5 lbs of rock salt dumped down the toilet. Much cheaper than antifreeze.

[IC2]

Drain and flush it the best possible then forget about it. Even if the smelly stuff stuck there freezes it wont expand enough to cause any damage (unless you have a majorly sized poo pyramid). I've never added any 'pink' stuff specifically to that tank in 40 plus years beyond what comes through the line to the toilet to protect it - maybe 4 ounces or so.

[Indy Glenn]

If you follow the manufactures guidance for winterizing your RV, chances are they include flushing your commode until antifreeze appears putting the pink stuff into your black tank........it doesn't need much.

g

[mtofell]

I think the OP can't/ins't moving the trailer so maybe dumping isn't an option?

I wouldn't worry too much if there's some amount in there. Pour in a gallon of antifreeze if you really want to be sure. The way I suspect a black tank is laid out, if/when it freezes the expansion will take the path of least resistance which is up into the open area. If it's fairly empty I just can't see it going out the side and breaking something. Kind of like an ice cube tray. When was the last time you saw and ice cube break out the bottom?

[JimBob46]

I always try to dump, close the dump valve, and then put in a gallon of pinks stuff and a little in the bowl to keep the seals wet. I think the tank is probably safe, but the drain pipe & dump valve are vulnerable--at least I think so. The pink stuff also keeps any residue in there wet so it will flush out easier the next time it is dumped.

Same for the grey water tank, although some folks leave the grey water valve open, I think any opening invites critters.

Just my opinion......

[IC2]

Originally Posted by JimBob46

..........although some folks leave the grey water valve open, I think any opening invites critters.

..........

Just think of them treading water before you send them on their one way trip down the stinky slinky at that first dump of the season

[nothermark]

I see it as a sliding scale deal. I never worry about a couple of flushes on the way home from the last campground where we dumped on the way out. What's in there does not freeze like water even without the antifreeze that ends up in there from winterizing with pink stuff. If there is more than that I would be looking at a pump out or if just a bit more maybe doing a 5 gallon bucket dump that I could carry to the toilet or dump station.

FWIW I would not use salt or windshield washer fluid or any other material that is harmful to people. If we cannot eat it then the septic or sewer system will probably also be harmed.

[sprayman]

if you have a couple of gallons in a 40 gallon tank i doubt freezing

would do any harm, it would need to be a lot fuller than that.

Jim