water in avc line

There is water in the line between the AVC and the pump. Can someone help me with why this is happening and what to do to stop the problem?

Thanks!

Probably a bad check valve. Can you post a picture?

Thanks for responding.

I can't post an image anytime soon, I will have to get back there with a camera. This is a Sta-Rite pump, typical(for this area) tank with an AVC on the side. Where would the check valve be located? I am not a well guy, just trying to assist some elderly shut-in folks and need some pointers. I had the pump re-built and it runs fine now, just need to get this well back in service. They are using the neighbors water, but she is moving soon.