City Water connection squirting out fresh water inlet

[TheTraveler]

Hey guys,
I was camping this weekend. My fresh water tank was empty from previously sanitizing and draining it. I hooked water to the city water connection thinking I would just run off of the city water without filling the tank. I ran the hot water for a little while to make sure the hot water tank was full before turning on the 110 HW heater. A while later I went out side and noticed water squirting out of the fresh water tank inlet. I turned off the city water and looked at the fresh water tank. Low and behold it was full.

How is water getting from my city water connection into my fresh water tank? Have I opened a valve between the two when I was sanitizing the system not meaning too? If so, which one do I need to close to prevent it in the future?

Thanks.

[JamieGeek]

Check your strainer on your pump you may have some debris which means you may have some debris in the pump preventing the valves to close.

Run the water pump for a bit and then see if it still fills the water tank. If it still does you may have a bad pump.

[bevedfelker]

Had same problem in my 2015 Vegas, but the water was flowing out the fresh water tank overflow next to the freshwater tank intake. I shut off city water. Turned on water pump and ran it for a while. Hooked up city water and no more water was backfilling into fresh water tank. Drained fresh water tank and never had the problem repeat.

Apparently there was a piece of debris that got stuck in the check valve on the water pump allowing water to backflow through the pump into the fresh water tank.

[TheTraveler]

Thanks guys. I'll clean out the strainer and try what Ed suggested. As you say, I suspect it's the backflow valve too. I know I can get a kit for replacing that if it's permanently damaged.

Thanks again.