Losing water out of overflow while travelling

Does the overflow have a tube or hose, that you could ... for lack of a better term, put a cork in it (or add a valve) to block or close the flow while traveling?

My Grand Design has a piece of, what looks to be pex tubing, very similar to what is used as low-point drains on many trailers.

Brand new trailer....let the dealer/mfg fix it right.

TomHaycraft wrote:
Does the overflow have a tube or hose, that you could ... for lack of a better term, put a cork in it (or add a valve) to block or close the flow while traveling?

My Grand Design has a piece of, what looks to be pex tubing, very similar to what is used as low-point drains on many trailers.

Yes, there are a pair of pex overflow tubes hanging down. Thought of your idea. I just don't know if it's "normal" for water to apparently siphon out with this type of tank, since it doesn't have a gravity fill.

JIMNLIN wrote:
Brand new trailer....let the dealer/mfg fix it right.

Jim, I agree, just trying to get consensus if this is really a problem or if the dealer will try to brush it off as normal. Still working through the rest of new trailer bugs, so will just add this to the list to be looked at under warranty.

djousma wrote:
Jim, I agree, just trying to get consensus if this is really a problem or if the dealer will try to brush it off as normal. Still working through the rest of new trailer bugs, so will just add this to the list to be looked at under warranty.

Yes, I've got the blue and red pex tubes for low point drains. There is then a 3rd tube, no valve, I think close to the dump valve for the freshwater tank over the axles that perplexed me initially. With no "vent" for overflow near the fill point, I've assumed this is a more direct overflow line from the tank. As I don't travel with much more than 1/3 tank fresh water (haven't dry camped ... yet!), hasn't been an issue.

Are you sure it is the over flow and not fresh water tank drain?

Interesting problem...

I don't own anything large like this but have heard that a up-suction from the roof vents may exist when moving down the roads that may pull water out of the tanks..

This is especially true with pulling fumes etc from the back and gray tanks. Might do something similar to the fresh water tanks?? I really can't imagine this is due to the fresh water sloshing around in the tanks from the trailer movement... Not up to an half a tank...

Maybe some of the 'better' fresh water tanks has baffles in them to keep the water from moving around...

I know I was surprised to see how low in height my 30 GALLON fresh water tank is. On my OFF-ROAD POPUP trailer the water tank is just 5-6 inches in height and is nestled inside my trailer frames for road hazard protection. I don't recall it ever siphons out fluids on its own...

Just thinking out loud here...

Roy Ken

enblethen wrote:
Are you sure it is the over flow and not fresh water tank drain?

Yes. There is a third line that is capped that is to drain the tank.

I have the same issue on a 2015 Jayco TT. Many other do as well. The easiest fix is to put shutoff valve(s) on the lines. If you put on valves make sure you label the fresh water fill and water pump switch so you remember to open/close the valves.

A common problem with many different makes. Just go to Home Depot/Lowes/Tractor Supply, etc and get your self a shutoff and several small hose clamps. When you need a full tank of fresh water, close that valve to prevent water loss.
Seems they're making the tanks different now with an overflow hole, problem is it entends down into the tank and once the siphon action starts it continues until the water level is below that line.