Water issues - overflowing fresh water tank

[Misfit011]

I have a 2018 Coachman catalina 281dds I'm currently hooked up to city water and now I have water pouring out of the fill tank any ideas why

[clr]

The backflow preventer is stuck open somewhat and allowing the city water to back fill the fresh water tank. Try shutting off the city water and turn on the pump and running some water thru a faucet. This may reset the backflow preventer flapper type valve. If this does not work the first time try again, after the second or third try you may have to replace the back flow preventer.

[Mr. Dan]

This backflow preventer is usually called a check valve and it's inside the pump if your pump is a Shurflow pump. See this thread ==> http://www.forestriverforums.com/for...ow-188907.html.

[ependydad]

It's pretty common and fortunately, the fix is pretty easy too:
Problem! Freshwater Tank Unexpectedly Filling When on City Water | LearnToRV

[Misfit011]

Thank you will try pump off and on

[Misfit011]

Unhooked city connection used pump reinstalled city connection works great so far thank you all for your reply

[JimMorrell]

Note: that backflow device is part of the water pump in most cases. On 2 occasions, I've had to replace the water pump to fix the problem.

[RStormC]

Install a backflow prevention valve on the output side of your pump. Given the number of posts regarding this issue it is obvious that the pump's valve cannot be trusted to do the job

[Mr. Dan]

Originally Posted by RStormC

Install a backflow prevention valve on the output side of your pump. Given the number of posts regarding this issue it is obvious that the pump's valve cannot be trusted to do the job

I have no dispute with this recommendation. I've trusted my two pumps and they have both failed me. If my pump's check valve fails again, I will install an external-to-pump check valve. There are multiple threads discussing (arguing, too) how to install them AND they are readily available.

[hreimers]

Our trailer came with a Shower Miser valve in the shower. It lets water circulate back to the potable water tank until the water gets hot. The idea is to not be putting unnecessary water in the grey tank. This was not explained to us and we just thought it was a shower valve and we overflowed the potable tank.

[mustardjim]

I had the same prob a few times. They are right back flow in pump is stuck open. You can buy a simple valve install it between the pump and the holding tank. Turn it off when you connected to city water and on when using the holding tank. I bought mine at a rv place 25 buc or something like that. Was very easy to cut the hose and add this valve. Problem is solved I just need to remember to open it when needed.

[BroMo]

Mine did the same when I camped in east Texas. Thanks for your help, it works great now just by running the pump