Fresh water tank filling when connected to shore water

[redzebra]

Have a 2000 Airstream LandYacht XLC MH. When connected to shore water supply my tank keeps filling up and overflowing. Having to drain every couple of days. Anyone else ever have this issue. Suggestions as to how to fix it.

[m.hony]

I doubt this is what happened to you-
And I doubt it will be of any help-
But- I am sharing a newbie experience because it was funny-
When we first bought our trailer, the guy doing the walk-through showed us incorrectly how to hook up city water- we were hooking up the city water connection to the black tank flush- some how or other- because gray water and black water are 2 separate systems- maybe through the vent stack- the black tank was filling, then the gray tank was filling, and then the water ran out of the shower. I had just set up camp and sat on the couch. I had been arguing with my wife that we had too many towels. Water ran out of the shower and all over the floor. At that point I was glad we had 17 towels for 2 people to camp 1 night- We lived that weekend with no water. I learned what I had done wrong. The next week we had everything under control.

[Protagonist]

Originally Posted by redzebra

Have a 2000 Airstream LandYacht XLC MH. When connected to shore water supply my tank keeps filling up and overflowing. Having to drain every couple of days. Anyone else ever have this issue. Suggestions as to how to fix it.

There should be a check valve in the system to prevent back-flow into the freshwater tank. A damaged or missing check valve could allow the tank to fill.

[Geobie07]

The valve on the line running to the fresh water tank from the shore water line could simply be open....closing it will fix the problem! Finding the valve could be a problem - on mine it is inside one of the bedside cabinets right where the shore water hookup is.

I've not had this problem but could have, as I could not figure out what the valve was for at first...fortunately it was closed and I eventually figured out what it was!

[idroba]

The only connection between the fresh water tank and the shore water supply pipes is the water pump itself. They have a check valve built in so the water does not flow backwards through the pump, but it sounds like the one in your pump has failed. Although the pumps can be rebuilt, the usual solution is to replace the older pump with a new one as they are not very expensive. A simple one can be had for as low as $60 and even fancy ones are under $200. They are a pretty easy swap out if you can get at it and do it yourself.

[ddruker]

X2 on the likely problem being the check valve in the pump. To test, disconnect and cap off the line that is on the output side of the pump - then reconnect your street water supply and see if water stops flowing into your tank.

Or if you are lazy - just replace the pump - it's not very expensive. I installed this one from Amazon - it's quieter and more powerful than the original pump that was in my 1999 rig - and it is a direct drop-in replacement.

Amazon.com: SHURflo 4008-101-E65 3.0 Revolution Water Pump: Automotive

[Protagonist]

Originally Posted by ddruker

To test, disconnect and cap off the line that is on the output side of the pump - then reconnect your street water supply and see if water stops flowing into your tank.

Wouldn't that cut off the backflow regardless? Backflow runs in the outlet side and out the inlet side, so if you disconnect the outlet side and cap it off, there's no backflow to test.

[ddruker]

Protagonist - I think that depends on whether you have a helper - if you do, then for sure disconnect the inlet side of the pump, and have your helper slowly turn on the street water supply - you'll know right away if the backflow preventer is working or not. Just have a bucket handy...

If you don't have a helper - like me - then it seems like the opposite would also work by process of elimination - if you cap off the hose leading to the output side of the pump, and then turn the street water on - if the water tank doesn't fill then that a faulty backflow device on the pump was the source of the water going into the tank.