Fresh tank overflow empties a third of my tank after filling

[Randy673]

Have a strange issue. I gravity fill my fresh water tank. When it’s full it pours out the the overflow tube briefly. Last year it worked fine. We just started a two trip. Now, when I fill the tank, as usual, when full it comes out the overflow. But it doesn’t stop. It keeps pouring out until the tank is down to 2/3s. Any insight would be appreciated.

[nisbitch]

It’s the siphoning that’s doing it. A couple bumps on the way and 1/3 of your water siphons out. A quick sharkbite valve will stop it.

[DaveMatthewsBand]

Have a strange issue. I gravity fill my fresh water tank. When it’s full it pours out the the overflow tube briefly. Last year it worked fine. We just started a two trip. Now, when I fill the tank, as usual, when full it comes out the overflow. But it doesn’t stop. It keeps pouring out until the tank is down to 2/3s. Any insight would be appreciated.

There’s at least a dozen threads explaining how to fix this, do a search for “fresh tank Sharkbite”.


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[Randy673]

That’s what I figured. Thank you so much. I can enjoy the rest of my vacation without analyzing this endlessly. LOL

[Randy673]

Awesome. I’ll do that.

[boyscout]

Awesome. I’ll do that.

Here's the valve you've been advised to install, a fifteen-second job:

https://www.homedepot.com/p/SharkBit...00LF/202270643

Fill your tank with the valve open, let it drain for a moment or two (to give the tank some headspace) and then close the valve just for the duration of your journey.

Really, REALLY important that you open the valve as soon as you arrive at your destination and leave it open at ALL times except when you're driving with a full tank. Do something so you can't possibly forget to open the valve - tape on your landing gear controls maybe? Also, if your journey involves significant elevation changes, to be safe you might open the valve momentarily partway through the trip up and down. These precautions are to avoid excessive pressure building in the tank and possibly rupturing it.

Good luck.

[jmbopp]

I have a shut-off valve and gravity fill port on our Imagine. There's enough air leakage around the fill cap for the pump to function normally.