Hokay, so plumbing question! (a little out of my element but I learn quickly)

The potable water system has me thrown for a loop. I noticed a leak in the engine compartment first, whenever I charge the water system through the deck line, but when I crawled around the port engine I noticed that it was coming from under the wall leading to the aft head. I was already planning on redoing the drawers built in to the port side so I tore up the lumber covering the freshwater tank. Visual inspection shows no leaks coming from the tank so now i'm left with what's in between this space and the engine compartment... the aft cabin head.
The aft cabin head is one molded piece that consists of the tub, sink, floor and wall. If i'm trying to check the potable water lines under this section do I need to saw this piece apart? My guess is yes but I was hoping to poll the forums and say hello at the same time to see if there is someone who has seen or dealt with a similar issue who could help point me in the right direction.
Thanks!
-J