Odd problem with my fresh water tank vent/overflow

[steveh326]

Just got back from my winter camping trip. No issues exce;t for one morning when it was 15 degrees outside, the water lines to the bathroom froze up so had no water there. once the temps got up some, the lines thawed out and no leaks.

I did experience an odd issue tho. This was my first time I relied on my fresh water tank for my only water. I filled it at home, tank gauge read full in the driveway. The whole way to our destination, water was leaking out of the overflow tube. My buddy was following behind in his truck and said the trailer was spraying water the whole way. Got to the destination about 3.5 hours from home, and the fresh tank read 2/3 full. My guess is that the wind across the overflow tube created a vacume effect, sucking water from the tank. No other leaks, etc. so that's the only thing I could come up with. Has anyone else experienced anything like this, and if this is truly the issue, is there a fix?

[Ford Idaho]

It is called the "siphon effect" there have been some post about it here.

Likely cause, water tank was too full.

Did you have water coming out the over fill tube before you left?

[bcunning]

I had a similar experience 2 years ago - some ice formed in the fresh water tank and the expansion of the layer of ice cracked the wall of the tank and created a small leak that was just a steady drip on the driveway I was parked in that night. I emptied the tank and sealed the crack from the outside with a hot glue gun using a soldering iron as a spreader of the glue over the crack.

[tyke8319]

My Cedar Creek, 34RLTS did the same thing shortly after we bought it (used from a private party). On our first trip to AK it syphoned all the water out of the H2O tank.
Found out Forest River periodically (or maybe some inept assembler) shoved one end of the overflow tube all the way to the bottom of the tank. I guess some RV's had the overflow drain line draped almost to below the level of the water tank thereby making the tank automatically empty while traveling. That was a rude awaking!!

[TxBgWood]

Our water overflow has a different issue. We are camping, hooked to park water supply. This morning there was all this water on the ground. It was coming out of the potable cap. We didn't put any water in the potable tank. How did this happen, and how to avoid it again. We have a 2015 Rockwood 25' Mini Lite Travel Trailer.

[youroo]

FW/Tank is filling thru Pump.Disconnect City supply and run Pump,might Fix problem. If not (Repair/Replace check valve in Pump Head! Youroo!!Reply to Post #5

[Trevor43]

Originally Posted by TxBgWood

Our water overflow has a different issue. We are camping, hooked to park water supply. This morning there was all this water on the ground. It was coming out of the potable cap. We didn't put any water in the potable tank. How did this happen, and how to avoid it again. We have a 2015 Rockwood 25' Mini Lite Travel Trailer.

More than likely your water pump bypass filter has slipped it's gasket and it is allowing your tank to fill up and then the through the overflow tube. Happend to me once and I solved it by taking the head off of the water pump and pushed it back into place so it would seal properly. Also, high water pressure can make the gasket move out of place if it gets blasted by high water pressure when first hooking up.

[stevemartin]

Water overflow is always a different issue.

[Taranwanderer]

This used to happen to me as well--fill up at home, and by the time I'd get to my dry camping spot 70 miles later, FW tank was down to 2/3. I attributed it to all the up and down hills on our interstates in PA, water was just sloshing around in there and spilling out the overflow. I put a stopcock valve on the overflow tube--open it when filling and using, close it when it's full for traveling. Remember to open it once you get where you're going or you could collapse your FW tank as you use water...you'll create a vacuum in the tank as you draw water down if air can't get in there to take up that space. Good luck!

[steveh326]

Originally Posted by Taranwanderer

This used to happen to me as well--fill up at home, and by the time I'd get to my dry camping spot 70 miles later, FW tank was down to 2/3. I attributed it to all the up and down hills on our interstates in PA, water was just sloshing around in there and spilling out the overflow. I put a stopcock valve on the overflow tube--open it when filling and using, close it when it's full for traveling. Remember to open it once you get where you're going or you could collapse your FW tank as you use water...you'll create a vacuum in the tank as you draw water down if air can't get in there to take up that space. Good luck!

thanks. I thought about adding a valve to the vent tube also but am really concerned with remembering to open it when I get where I'm going. Thinking about trying some sort of filter on the end of the tube to see if that reduces the suction/siphoning on it. if truly siphoning it may help cut down on the air flow across the end of the tube enough to eliminate or reduce it.

[Helmsey]

I have the same issue on my vent hose and I plan on extending it and running it back above the top of the fresh water tank. That should prevent it from siphoning out on its own.

[clarktod]

You should not need to worry about remembering to open the vent tube. The tank should vent through the fill tube too if you are drawing water with the pump.

[Taranwanderer]

Originally Posted by clarktod

You should not need to worry about remembering to open the vent tube. The tank should vent through the fill tube too if you are drawing water with the pump.

I wouldn't bet on that. You have a screw-on cap on your FW fill, right? If so, that may not let enough air in during use to keep the tank from collapsing under vacuum, especially if it's screwed on tight (which it should be.) I'd still want my vent open. Just add it to your set-up checklist. Checklists are your friend...

[steveh326]

Originally Posted by Taranwanderer

I wouldn't bet on that. You have a screw-on cap on your FW fill, right? If so, that may not let enough air in during use to keep the tank from collapsing under vacuum, especially if it's screwed on tight (which it should be.) I'd still want my vent open. Just add it to your set-up checklist. Checklists are your friend...

I don't think my fill cap is vented, but that doesn't mean I can't vent it myself - this may be the ultimate solution as the fill cap is well above the tank level... thanks to all... I just need to come up with a way to keep rain water out.

[clarktod]

I actually have a pressure fill and it does not have a cap so in my case I don't have to worry about the cap. If you have a gravity fill then a cap would cause a problem.