when im hooked up to city water will the fresh water tank fill up? I noticed my fresh water gauge came to full when I did this? new to this situation? thanks

When you are hooked to city water all those little plastic water lines are pressurized to whatever the park is supplying you or what your regulator allows. Safer to fill the tank and use the pump.

Not in any trailer I have owned or even heard of.

No it should not be able to reverse through the water pump and fill your fresh water tank.Have not experienced that in 4 trailers.

The city water should connect to your water lines after the 12v DC pump, which has a one-way valve so water can only flow out of the tank/ out of the pump.You would need to add a ball valve off a Tee after the pump and route it back to the water tank, or the water line before the pump to flow water from city to tank.You would need to do this manually and monitor it to turn it off when full as it would run constantly into the tank and out of the air vent or fill spout.

Some RVs have a valve to fill the tank, if it is open or leaks, the tank will fill. If the check valve in the water pump leaks, that too will fill the tank. Common problems.

frsh water tank | Good Sam Community

17 Replies

poppa
Explorer
Feb 18, 2020
update. I either had water in the tank or the check didn't check the first time but last wknd it was empty when I hooked up to water and didn't fill, was empty when I disconnected.
GrandpaKip
Explorer II
Feb 18, 2020
kellem wrote:
shaner82 wrote:
Mine shows full the second I connect to city water. It has since it was brand new. The tank is empty one second and shows full the next, so I don't believe it's backflowing into the tank.

This is also a thought as my previous trailer did the same......empty tank read full apon city hookup.

Then the question becomes why is this happening?
kellem
Explorer
Feb 17, 2020
shaner82 wrote:
Mine shows full the second I connect to city water. It has since it was brand new. The tank is empty one second and shows full the next, so I don't believe it's backflowing into the tank.

This is also a thought as my previous trailer did the same......empty tank read full apon city hookup.
shaner82
Explorer
Feb 16, 2020
Mine shows full the second I connect to city water. It has since it was brand new. The tank is empty one second and shows full the next, so I don't believe it's backflowing into the tank.
allen8106
Explorer
Feb 13, 2020
Some rigs have a valve at the pump to shut off suction from the tank when on city water. If that valve is open it can back fill the tank. My 2010 Jayco is set up that way.
poppa
Explorer
Feb 11, 2020
thanks for all the replies. first time out on new tt. I used the hose end regulator, just noticed the tank filled. don't really want that but don't really want to use pump if I don't have to. the valve on the discharge mite be the trick, or a better check valve. thanks!
Bobbo
Explorer III
Feb 10, 2020
The PEX, itself, can take the pressure. It is the fittings connecting the PEX together that poses the risk from high pressure.
Huntindog
Explorer
Feb 10, 2020
ajriding wrote:
Also, maybe the city water pressure is too high and causing the valves to leak?

A pressure regulator is a safe thing to have for these plastic water systems in RVs to protect against high city pressure.

Well the pumbing lines are PEX, which is commonly used in Houses now. TT fixtures are often cheap/poor though there is some good stuff being used.
ajriding
Explorer II
Feb 10, 2020
Also, maybe the city water pressure is too high and causing the valves to leak?

A pressure regulator is a safe thing to have for these plastic water systems in RVs to protect against high city pressure.
joelc
Nomad
Feb 10, 2020
Your valve in the pump is not working and is allowing city water to flow into your tank instead of stopping at the pump. I had the same problem. I installed a water shut off valve after the pump to stop the back flow. If you are going to use water in the tank turn it on, if not shut the valve to prevent the back flow. This fix being short of risking water flooding the RV and bursting your tank from pressure.