I'm new to RVing, and I don't understand my fresh water tank. I assumed that it would be a sealed tank. If I fill it beyond 3/4 full I will lose A LOT of water when the coach is moved. I don't know where the extra water goes at fillup, but it comes from a hose protroding from the sealed bottom of the coach, which is a 1999 Beaver Monterey Redondo. The hose is not the low point drain.
I had the same problem with my 07 KZ Montego Bay 5th wheel (apparently that is a common problem for that unit) and researched the issue a great deal. I was lossing a 1/4 plus of my tank just by driving a few hundred miles. Wife was not happy to run out of water in the middle of a shower.
What I ended up doing was placing a shut off valve in the overflow tube.THEN, so as to not try and fill the tank or use it with the valve shut, I put labels on both the outside fill port AND on the pump switch inside the RV. The only other option I came across in my research, was to do as already suggested, extend the overflow hose lenght and mount it higher.
valhalla360 wrote: The tanks have a vent built in for a reason. If you want to move it up higher, that shouldn't hurt but don't try to seal up the tank or you will eventually break something. If you are lucky it will be something easily reached and cheap.
I have come to the conclusion there is nothing easily reached and cheap on a RV. Bill
The screen in the vent line beside my gravity fill on my TT popped out, I came up with the cheapest solution to losing water while driving. I took a simple bolt, smaller than the hole and put a couple wraps of black electrical tape on it, but small enough to jam in the hole as a plug. Can't get any cheaper than that. I would sometimes lose 5 or more gallons on our way to the racetrack due to cornering. Now I don't lose a drop. Put it in after filling and take it out once there.
valhalla360 wrote: The tanks have a vent built in for a reason. If you want to move it up higher, that shouldn't hurt but don't try to seal up the tank or you will eventually break something. If you are lucky it will be something easily reached and cheap.
I have come to the conclusion there is nothing easily reached and cheap on a RV. Bill
2008 Newmar Mountain Aire 450 HP CUMMINS ISM ALLISON 4000 MH TRANSMISSION TOWING 2014 HONDA CRV With Blue Ox tow bar A man who carries a cat by the tail learns something he can learn in no other way. -Mark Twain
I'd put a Tee in the line right where it comes out of the tank, then out of the top of the Tee run a line up a few inches to prevent water from spilling out. this will stop water from being siphoned out of the tank.
The tanks have a vent built in for a reason. If you want to move it up higher, that shouldn't hurt but don't try to seal up the tank or you will eventually break something. If you are lucky it will be something easily reached and cheap.
Tammy & Mike Ford F250 V10 2021 Gray Wolf Gemini Catamaran 34' Full Time spliting time between boat and RV
I'd be concerned with that valve when climbing or descending. Seems to me that you could build up excessive pressure or a dangerous vacuum in the FW tank - at least more than that system is designed to handle.
eHoefler wrote: Install a valve in the overflow line. When full after filling, close the valve and arrive with a full load of water.
Just don't forget to open it when you start using the water pump.
Or don't forget to open it when you fill your tank, I saw the results of this when I guy I was traveling with to Alaska forgot to open the valve and the tank expanded like a balloon an broke the support structure for the tank. Myself and another guy spent all afternoon doing a fiber glass and metal repair to support his tank again. How I solved this problem after losing many tanks of water was to reroute the overflow line higher than the exit hole. I made a clip to hold the line up to the bottom of the floor about 4 ins higher than where it comes out of the top of the FW tank.
