Winterizing: Holding tanks dry or not?

I will reply to the "open valve" by stating that in my 30 plus years of RV'ing with RV's that have holding tanks I have never had an issue with leaving the slide valves open for extended periods of time when the RV was not in use. Anything that dries up tends to rehydrate real quick the next time it's used.

I have the good fortune to have a dump station at home, plus I never worry about weight issues with my truck camper or travel trailer, and often return home with loaded tanks. I find the drive home does a pretty good job breaking things up in the black tank versus dumping at the campground.

And totally unrelated to the OP, in the summer I do dilute holding tank deodorant in a bucket prior to pouring down the toilet. A have a clear elbow I always leave on my dump valves and I've found that if I pour some blue deodorant straight in the toilet after dumping, it just goes down the pipe to the valve and doesn't really get mixed in the tank, as is evident with the clear section of pipe showing an initial gush of blue. So mixing with a gallon or two of water works better prior to adding it to the tank.

Now while some of you are winterized for the long winter ahead, here in the NW I'm getting ready to refill my truck camper with fresh water and head into the mountains to enjoy some snow, and go for some quiet hikes in all but abandoned RV destinations. Hans

x2 for obsessive attention to detail in winterizing. All it takes is once having to have frozen & broken parts replaced.

Same as everyone else. A little AF in all tanks and traps. However I limit the pink to anything touching fresh water and use windshield AF in the tanks and don't forget to leave a little of some kind of AF in the toilet bowl. Both to keep gas/smells from coming up and to keep the seals wet and lubed.

With RoadAbode, We drain everything, and just put a little pink stuff in each tank and all the drains (shower too!) after winterizing. Some gets in the tanks when we put the pink antifreeze through the fresh water pipes anyhoo. Just updated my blog with all the stuff we do. Friends of ours just got a Class C and were asking, and it was easier for me not to forget something by writing it up for them to read with some pics. Told them to read a lot here too. (Hi Jon & Kimberly!) :)

Here's the deal on this and other procedures we use each year. We somehow learned how to do this and nothing bad has happened to us by doing it this way, so that's how we're going to do it from now on. If something changes (busted pipes, pink ice cubes)then we do some research and find out what we did wrong and change it. Everyone will have an opinion based on the fact that it's the way I've done it and nothing bad has happened. There are, of course, some sound engineering reasons to do certain things, and some of them were mentioned here.

BTW, there are no sound engineering reasons why black tank sensors never read empty :)

Obsessive:

-Flush/drain tanks.
-Air or antifreeze through pipes.
-2 cups antifreeze into each sink & shower P-trap.

-Re-Drain (diluted) antifreeze from tanks. Drive at various angles to ensure drainage.
-Close valves.
-2++ More cups antifreeze into sink & shower P-traps + toilet. More if tanks aren't Completely drained.

This results in:
-Undiluted antifreeze (no pink ice cubes) in tank valves and P-traps.
-Enough moisture to keep valve seals pliable and tank crud from drying out and killing level sensors.

I dump the tanks and then pump the pink stuff through everything and make sure at least 1/2 gallon or so gets down into the black tank. I also pour into all the sinks to make sure the traps are covered, and in the process I'm sure some makes its way to the grey tank. Never had an issue, and remember a little water sitting in a 30-40 gallon plastic tank isn't going to expand enough to cause a problem.

Road Dog wrote:
After draining black and grey, I pour one half gallon in each tank. Cheap insurance!

Agree with the cheap insurance aspect. I "waste" a fair bit of pink stuff when winterizing. I let a lot run out of the faucets, and then pour even more down into the trap. I figure the net result is about 1/2-1 gallon going into the respective tanks. The added $5 in this is relatively small price to pay.

Right, what harm in having a dry holding tank? I've found that whatever crud fouls my tank sensors falls off during the winter and they work better for awhile in the spring. Well, sometimes later on in the winter also if I have a chance to take a trip

After draining black and grey, I pour one half gallon in each tank. Cheap insurance!