Winterizing Question: Is My HWT Check Valve Leaking?

I’ve had both the fresh water city check valve fail and the hoywater check valve fail- Took me two gallons to figure out I was filling up the hot water holding tank after I shut the by-pass off. The city water was kind of funny- I’d try to pressure up the system with the water pump and it would shoot out the side of the rv. Same trip the black water valve wouldn’t close.........