Originally Posted by O-man
there is a drain valve for the potable water tank, nut that is not where the problem is, it is a continuous flow from over flow tube
That valve labeled "normal", "tank", and "sanitize" is probably where the problem is. In normal mode, it's supposed to feed the plumbing but NOT go into the tank. Turning it to tank lets you use city pressure to fill the tank.
I have a feeling the valve is bad and is letting a trickle of water go to the tank while in the normal position. Again, it's NOT supposed to. If it is, then the overflow line will have water coming out of it.
Edited,, should have read the whole thread. I'm a day late and dollar short,,, again.