[Tiara Open] fresh water container

[carxfrog]

I have a 2003 29 Open with a leaking fresh water system.  When the fresh water pressurizes, with all valves turned off, it leaks into the bilge.  I can't see when the leak is coming from via the access hole by the hot water heater / via the access port under the stairs in the cabin / via the fresh water line and connections in the engine compartment.  So I am left with wanting to get a full view of the container.  What is the best way?  

Thanks.  JIM