Fresh water tank over flow

[Rick Daniels]

Just had an experience which leaves me in the dark.  Filled my fresh water tank, turned the supply hose connection off considered the job done.  Went outside a few minutes later and a steady straight stream of water was coming from the bottom of the coach near the dump valve.  In closer examination and after checking to see that the dump valve was fully closed, and it was, I saw that the stream of water was not coming from the dump valve but near it.  It was a nice round stream, as if it was coming from perhaps a overflow pipe or something.  It drained my tank down to 50% before stopping.  I might add that when the tank hit 100%,  I heard an unusual noise that stopped when I turned the fill switch off inside the coach.  When the ground get a bit less muddy I will crawl under the coach to see if I can tell where it is coming from.  Any ideas?

[Bob Bulot]

 When I fill my freshwater tank, the overflow vent tube will  siphon out about a gallon or two of water Onto the ground until the siphon is broken.  In my coach, this appears to be normal.

[Dan Murphy]

I have to be very careful to not create a siphon effect when filling the fresh water tank. I try to stop the fill before it comes out the overflow pipe which isight next to my low point drain for the tank.
If I let my tank fill until it comes out the overflow it will continue to siphon out even after the supply it turned off.

[Jerry Carr]

Rick, Dan is right on I have had the same thing happen 

[Gerald Farris]

Rick,
The siphoning effect on an overfilled fresh water tank has been discussed on this forum many times and it varies from one coach model to another, but it is a common problem on all coaches that do not have automatic fill valve cutoffs.

The only correction is to not overfill the tank or install an anti-siphon valve at the high point on your vent hose.

Gerald 

[David T. Richelderfer]

When I fill the fresh water tank to the point it overfills ours, too, will continue to siphon for several gallons.  I found that to get the siphoning stopped, just turn on the faucet at the water bay for a few seconds.  First stop the water going into the tank by closing the water fill switch, then turn on the coach's water pump, and finally turn on the water bay's faucet.  I assume the act of pulling water out of the water tank stops the siphoning due to the need for air going into the tank through the overflow to replace the water which the pump is pumping out.  I also suspect that "over filling" the water tank makes its sides bulge out a bit, and that would add pressure to the siphoning effect making siphoning a bit more difficult to stop.

[mike groves]

I had that happen to my '99 as well and the only precaution I have taken is to monitor and shut off the fill immediately upon reaching the FULL indication.

Mine also has something of a weak FILL valve in that not only do I need to turn the fill switch off, but I immediately turn on the sink and then the bathroom taps in order to allow my valve to actually close.

That may also be a problem in your '99 so that even though you turned off the fill valve it is still open and the tank continues to fill, then overfill then you see the stream from the over flow.

Mike

[Jeff Ramey]

Happend on our 2000 Patriot Thunder also. I was filling the tank and got distracted. When I heard water pouring from under the coach onto the concrete pad at the KOA, I immediatly ran over to shut off the water faucet! It took a few minutes to stop pouring out much to my chagrin. I left camp quietly and avoided making eye contact with anyone shortly afterwards. 

[Rick Daniels]

Thanks to all.  Tried turning on the faucet in the water bay ad no siphon. Problem solved.  Thanks again

[Bart Mix]

I just made a measurement & installed a slight extension along with a simple anti-siphon device on my overflow vent several years ago & no problems since. A simple & inexpensive job.
Bart from VA
03 Beaver