I have dealt with the same problem on my boat.
Start with the tanks
. Does it smell like holding tank water
? If so you know where to start looking. Either way, access the tanks
and look for leaks at the tanks and around the pressure pump and water
heater. Obviously check with the system pressurized. While we are at it turn off the pressure pump and see if that has an impact.
If it is not leaking from inside, some things I have addressed on Cynosure- re-bedding the genoa
tracks and where the chain plate
goes through the deck
. If there are issues with these, check for core rot
in the surrounding deck
None of thar repairs
are that difficult just a PITA.