Fresh water tank overflow drains tank on hills

[Bruce W]

I just went on a trip that took me up and down some 9% grades. I had filled the water tank before I left knowing that no water would be available at camp site. When I arrived I found almost half of my water gone. It looks as though I lost my water out of the overflows on the hills as I didn't find any other problem with water system.
My 2008 Challenger has 2 overflows one at the front of the tank and another at the rear.
I'm thinking of putting shutoff valves on the overflows to stop my waterloss.
Has anyone else had this problem?

[Bruce W]

I just went on a trip that took me up and down some 9% grades. I had filled the water tank before I left knowing that no water would be available at camp site. When I arrived I found almost half of my water gone. It looks as though I lost my water out of the overflows on the hills as I didn't find any other problem with water system.
My 2008 Challenger has 2 overflows one at the front of the tank and another at the rear.
I'm thinking of putting shutoff valves on the overflows to stop my waterloss.
Has anyone else had this problem?

[doghowz3]

Bruce:

I was pulling out of a campground and saw that the two overflow pipes on the Challenger 377 were draining. The MH was canted to the passenger side and so I thought that I was just "untopping off." I pulled over and found that they continued to drain. I had not switched the fill selector off of city water. The fresh water tank was empty at the next campground.

I am at a loss for what is going on.

Anybody our there have some guidance for us?

[Bruce W]

Paul,
Is your fresh water tank long and flat on the passenger side with rear and front vent hoses?
Our motorhomes are probably similar other then layout so maybe this is a problem on newer Damons.
I'll leave an email to Damon and see what they say.
Thanks
Bruce

[Hurricaner]

There is no issue with the older ones as they vent through a line that is mounted with the fill port which is probably 2 feet above the tank. However this is a common problem on many motor homes although it seems a little ridiculous that it happens at all.

Sam

[doghowz3]

Bruce,

Your description of the fresh water tank overflow hose locations is right on the mark for the Challenger 377.

My wife asked this morning if I had contacted Damon about what I was doing wrong/what they may have designed wrong. I hadn't done that yet. I'll await what response they give you.

Thanks (almost had a typo there and wrote "tanks")for your reply.

Paul

[Bruce W]

Hi Paul,
Still haven't gotten a response from Damon. I'll call them tomorrow if I don't have response to my email by then. I'll pass along anything find out.
Tanks
Bruce

[Bruce W]

Hi Sam,
I guess Damon never heard the motto, " If it works don't mess with it."
Bruce

[Bruce W]

I got a response from Damon,
================
Hi Bruce,

Yes I have heard of this and you are correct with the installation of the
valves.

Respectfully,

Martin M. Johnson
Regional Service Manager
================
I guess adding shutoff valves to the overflow lines will prevent water loss while traveling but Hurricaner mentioned that the older models had the overflows exiting higher which might be a better solution. I think the overflow is also the vent to allow air into tank as the water is used which might create a vacuum in the tank if water is used while the valves are closed. Also I see no reason for 2 overflows and putting a valve on one may be enough to minimise the problem.
If anyone has come up with a better solution then adding shut off valves to the overflow hoses, the RVnoob would be greatfull.