Interesting winterizing question.

aftermath X2

JaredWPhillips wrote:
Personally, I drain them as much as possible. Then I dump a gallon or so of antifreeze into each tank.

This is overkill. Once the tanks are empty, all you really need to do is pour the pink stuff into the sink traps, shower traps and then into the toilet. The extra will flow into the empty tanks and collect at the valve. Nothing is going to freeze. The traps will be safe as well as the toilet flusher and the waste valves. You can pour gallons down the tanks but you don't really need to do this. I have followed this method since 2000 and haven't had any trouble.

X2 Jared’s post.

Freeman2004 wrote:
I never had to winterize a black or grey tank.
Just how does one do this? They are never really totally empty.

I know you said "black or grey tank" but is that what you really mean, just the tanks? If so, there really isn't any winterizing to do as residual antifreeze left over from wintering the trailer's fresh water system will end up in the grey & black tanks anyway and work it's way down to the waste gates.

Thanks. Good to know.
Gotta relearn this entire process before we hit freezing.

The only area that could be damaged by freezing would be the valves, so a gallon of antifreeze into each tank will ensure that the antifreeze flows down to the valve areas.
The tank will not freeze and bust; the only way that would be possible is if it was full of water.

Personally, I drain them as much as possible. Then I dump a gallon or so of antifreeze into each tank.