Winterizing gray and black tanks

[tentcamper1]

Originally Posted by Willis

Personally, after flushing the black and grey tanks for the season and closing them, I add a gallon of antifreeze to the black tank (the grey tank will get enough antifreeze in it just from filling the lines and traps). I don't think there is any way to know for sure that the tanks are completely dry and I don't want any residual water sitting against the valve areas to freeze. A gallon of antifreeze is cheap insurance.

x2-

[revrnd]

Originally Posted by Willis

Personally, after flushing the black and grey tanks for the season and closing them, I add a gallon of antifreeze to the black tank (the grey tank will get enough antifreeze in it just from filling the lines and traps). I don't think there is any way to know for sure that the tanks are completely dry and I don't want any residual water sitting against the valve areas to freeze. A gallon of antifreeze is cheap insurance.

X3

That's the same procedure that I've been following w/ no issues up here in Ontario.

[bobsquarepants]

After pulling the anode rod and drain the water heater I use a wet and dry vac to pull out the remaining water...you would be surprised how much gets left behind.

[trudinator]

I flushed out our gray and black water tanks yesterday before winterizing. We're using the blow-out method. I couldn't believe how much "gunk" (I won't go into nasty details) was still left in the tanks. I rinsed and dumped them three times to make sure they were both clean as a whistle. Should I leave the dump valves open during winter? DH drained the water heater and apparently didn't read the info about the residual pressure....he came away totally soaked!

[F and E Damp]

The temperature at which water with "stuff" in it will freeze declines as a function of the percentage of "stuff". Your black tank contents probably wouldn't freeze until about 24 degrees, but why would you leave that stuff in there? Grey tank would probalby be OK down to about 28 degrees, but again, why would you leave stuff in there?

If both tanks are at relatively low content levels (say less than a quarter full) there's enough air space for them to freeze without doing any damage.