Fresh water siphoning problem

[Dragginourbedaround]

I think what is really happening is centrifugal force during turns and normal road motions driving down the road is sloshing the water in the tank, so the peak of the wavefront is higher than the vent tube, making water flow out of it.  Do this often enough and you can drain the tank well below the level of the vent.

My rig has been sitting since last Sunday. Twice I filled the tank and twice it siphoned out at least 1/3 of the tank. I tried carson's remedy and it worked. Yesterday I filled it until it showed full on the inside panel and I stopped. This morning it still shows full which is probably only two thirds to three quarters full. 

 

[Mikeh449]

how level is your unit on my 5er when I fill water if the trailer is not level or nose up I only get 3/4 tank of water but shows full on display

 

[carson]

A little tidbit on the sensors on the tank.

  If you have the electro-mechanical sensors (wires externally attached) you will notice the locations correspond to what is going on. 3 sensors and one ground, if I remember correctly.
They are not located at the extreme levels; rather about midway spaced evenly. That means the tank will be considered full on the gauge, when it reaches the top sensor.

  Any more water will not show on the gauge and is probably considered full at the top sensor.

FWIW.

 

[Dragginourbedaround]

how level is your unit on my 5er when I fill water if the trailer is not level or nose up I only get 3/4 tank of water but shows full on display

It's within a quarter bubble.

 

[wincom6]

I had this problem with a 2005 Forest River Georgetown, I did what Lou Schneider recommended and solved the problem. It was a simple fix, I just rerouted the overflow to a higher position.  Good luck and happy camping.

 

[Dragginourbedaround]

I had this problem with a 2005 Forest River Georgetown, I did what Lou Schneider recommended and solved the problem. It was a simple fix, I just rerouted the overflow to a higher position.  Good luck and happy camping.

If I ever what a full tank of water I think that's what's going to have to happen.

 

[Dragginourbedaround]

As an update:

We traveled 500 miles in two days with about a quarter tank of fresh water. During setup I filled the fresh water tank until the overflow tube started to drip and switched the valve to city water. It stopped dripping almost immediately, no siphoning. Still have a full tank this morning.