Thanks everybody. I've removed pump, blew in both sides(one air blows through, other none). I've removed outgoing pump line and constant flow of water (presumably gravity from tank). Still nothing. Not a drop out faucets, nor air being bled from lines. Tank is full as water is coming out overflow. I plugged water inlet, no improvement. I plugged water inlet with air fitting, added compressed air and water comes blasting out overflow in both valve settings (fill tank/city pressure). It appears water inlet valve is not doing its job of closing off to allow sealed pressurized system? As I mentioned, went to RV supply and no replacement for my setup.shy of cutting both lines and adding an inlet valve to each one separately, I'm at a loss. Thanks again for all help/suggestions! Greg