Winterizing black/grey tanks

[Darryl_]

Hello everyone,

Im sorry if this has been posted a million times, but I have a stationary travel trailer 2011 36bhds that is seasonal and hooked up to a park sewage system. Im wondering the best way to winterize the grey and black water tanks. Ive read some people just drain and flush and leave the tank valves fully open for the winter, and ive also read that some drain and flush and add antifreeze to the tanks and leave valves closed.

This is my first trailer and Im curious which way is correct, and how much antifreeze would need to be put into the tanks. The owners manual mentions nothing that i can see about winter prep for these tanks aside from draining

Thanks in advance for the help!!

[Camper_bob]

I drain the tanks and then put enough AF in to keep the knife valves wet.

But then, we don't get severe freezing here, so it's not a big worry of mine. In the waste tanks, if there's a little water left in there that freezes, there's plenty of space for that expansion, so nothing's going to break.

But if the rubber seals on the knife valves dry out, you could have leaky valves when it warms up.

[NVGun40]

You state you are curious "which way is correct". With that you will get many different opinion on which way any one of us thinks is the correct way.

Bottom line, whichever way provides protection from the tanks freezing and getting damaged throughout the winter is correct.

You say many drain and flush out the tanks and leave them connected to the park sewage with the valves open. Depending on your climate, there is nothing wrong with this. Many people dump a little antifreeze down in the tanks. Nothing wrong with this either.

As long as you are getting the tanks clean and flushed out completely that is the key.
Personally, I wouldn't leave the valves open. What little bit of residual water stays in the tank after being drained and flushed is not enough to hurt anything.

Advantages of putting antifreeze (it doesn't take much), is that the antifreeze does provide a lubricating effect on the drain valves.

[Jagiven]

You have the advantage of being connected to a sewer system. If it was me, I would flush the tanks really good. If you do not have a black water tank flush built in. Open the black tank valve, and pour a few 5 gallon bucket loads of water quickly down the toilet. This will flush a lot of the debris down the drain. I would then open the grey water valve, and just let them both drain for 5 minutes or so, before closing the valves. It is not a big deal if any water is left in the tank, as there is a huge surface area for any small film of water to expand in.

While the tanks are draining, prep the FW lines. My preference is to use a little compressed air to push out the bulk of the water out of the lines (not required).

Then pump the RV antifreeze through the system. Make sure to put plenty of antifreeze down the P-Traps, and in the toilet.

I like to blow the antifreeze out of the FW lines, and use that antifreeze to dilute the water in the P-Traps. Which in turns goes into the waste tanks.

I also dribble a little mineral oil down the P-Traps and float some on top of the Toilet. The mineral oil keeps the antifreeze from evaporating. Do not use vegetable oil, or you will have a sticky mess in the spring.

If you have a black water tank flush that pipe needs to be winterized too.

[Camper_bob]

And don't forget the outside shower as well as the city water inlet.

Run AF through the outside shower outlet just like any other fixture.

To get AF into the city water inlet, stand aside and depress the check valve while pumping AF into the system. Don't forget to stand aside, that red AF I'm sure stains pretty bad. Did I mention to stand aside as you depress that check valve?

[Darryl_]

Thanks all. Is a gallon enough to pour in the tanks?