Draining water holding tank for winter

[dcotton4]

Ok so I drained the fresh water holding tank on my 2002 Montana 2850RK by opening the valve under the camper and let it drain until it was done then I even blew a little air in it just to make sure it was empty. I then moved my camper to the location I am storing it for winter and when I had the camper tilted so that the drain end of the tank was lowest it started draining out more water. It ran for about 8 or 9 minutes probably draining an additional 10 gallons of water. Why didn't all the water drain out when I was winterizing it ? Glad I caught this problem or I could have been replacing a tank!

[JRTJH]

Few trailers sit 'true level" on any site and few tanks were installed at the factory in "true level" condition. Plastic tanks "bulge" when they have anything in them. Given those considerations, any tank will "drain a bit more" when it is moved about with the drain open. I always get an extra gallon or two out of my holding tanks when I move my trailer from one place to another.

8 or 9 gallons seems like a bit more than usual, but even that shouldn't be enough to freeze, expand and damage the tank. Think of an ice cube tray, as the sides "constrict the expansion" the top surface of the forming ice is open so the ice can freely expand upward. I wouldn't think you'd have any damage from half an inch or so of water laying on the bottom of the tank.

The big problem comes from draining black/gray tanks as you did, then moving the RV and having a couple gallons of water flow from the bottom of the tank into the valve area or into the connecting pipes between the outlet and the valves. That water, if it freezes has nowhere to expand "upward" and would probably split the pipe or damage the valve seats if allowed to freeze in that location.

I always open my dump valves after I back my trailer into the pole barn, just to eliminate any pooling in the pipes or against the valves.

[geo]

John is correct. When I had the coroplast off on my Alpine, I noticed (and documented on this forum) that the fresh water tank had a rounded bottom and that the drain was located more towards the tank side - leaving an good volume of fluid untouched by normal, level, draining procedures. In fact, I could even see "particulate" in the tank that seemed to be sawdust from the building of the Alpine! From that time on, when I drained the fresh water tank, I parked the Alpine on a slope so the fresh water drain was closer to the lowest point of the fresh water tank.

Ron

[Pmedic4]

Originally Posted by dcotton4

Ok so I drained the fresh water holding tank on my 2002 Montana 2850RK by opening the valve under the camper and let it drain until it was done then I even blew a little air in it just to make sure it was empty. I then moved my camper to the location I am storing it for winter and when I had the camper tilted so that the drain end of the tank was lowest it started draining out more water. It ran for about 8 or 9 minutes probably draining an additional 10 gallons of water. Why didn't all the water drain out when I was winterizing it ? Glad I caught this problem or I could have been replacing a tank!

I read your post about draining the fresh water tank, and winterizing it, and assume the question about the fresh water tank was after you did all those other wonderful winterizing tasks? Blow out water lines/pump RV antifireeze into the lines, etc?

[greengiant]

John, Do you leave the black/grey valves open all winter with the cap on the outlet? or once parked for good, just open, drain, and then close? I didn't know if there was a best position for longevity on those valves or if it matters?

I am also in the situation of winterizing in the driveway, and then moving a couple miles to store for winter. I just did my first mild winterizing (blow lines, open faucets, empty tanks) and dropped it at storage today, since I won't use it till tailgating and hunting toward the end of November at which time I do a full winterization. Till then I expect to see enough freezing temps to justify the hour of work.

I collected waste water in a 5 gallon bucket ( about 5 gallons, but some of this was intentionally added to black tank at the dump station) in the driveway that collected at the valves from the drive home last weekend (after dumping), and then collected another gallon of 'juice' after driving over to the storage lot.

I also leave the fresh tank low point drain open when moving it, but closed it once I left it today. When I've parked for winter in the past, I usually leave that and any low point drains open, and put a rag and rubber band on them to allow anything to run out. I like to do this in the driveway, as it is one less thing to think about ( and forget about) when parking it over in the lot. This is likely not necessary if you just open it till it stops dripping once it's parked for good, and I didn't do it today beacause I just make sure all 3 of my low points had nothing coming out before capping/closing. I've never liked to keep these wide open in winter since you never know what might crawl in.

I dream of someday having a pole barn with 30amps, a hose with fresh water, and an underground sewage/septic line next to the camper......

[JRTJH]

I leave the tank valves open all winter. I have a sewer connection cap with a garden hose connector on it. After parking the trailer in the pole barn, I put a 5 gallon bucket under the sewer hose outlet, open the garden hose connector and let anything that might have migrated out of the tanks drain. Usually it's less than a gallon or so. I empty the bucket, put it back under the drain and leave the garden hose outlet open all winter. Some people express concern that a mouse might get in there, but honestly, where would it go except into the black or gray tank? And if it does get in there, that's one less that could have entered the trailer proper LOL Besides, a mouse can't do any damage in the tank and will "flush out" with the rest of the black tank effluent at the first dump.

As for the low point drains, they need to be closed after using compressed air to clear the lines. Otherwise, any antifreeze you pump into the system would simply flow out of the low point drains. If you don't use antifreeze in your hot/cold lines, then it wouldn't matter. Of course the fresh water tank drain is not a part of that. I leave mine FW tank drain open until I get to the pole barn, then I close it for the winter.

Realistically, if you don't have any potential for water to collect in the dump valve lines, there's no reason to leave them open. I leave mine open just because I don't know how much "extra" might find its way down to the valves and condensation will produce some, although probably less than a cupful all winter. I've found that once I put my trailer away for the winter, I prefer not to go pulling valves, opening or closing drains or doing any movement of the trailer or any of its components. Once vinyl and rubber get cold, I just prefer to leave it alone. A slide valve that's frozen to the gasket may be damaged when trying to open or close it when extremely cold. I set up my trailer so I don't have to do any of that once I walk away in the fall. It makes for peace of mind if nothing else LOL