Wanting to install new vinyl in my 2006 19' Bambi SE, I first pulled the old vinyl up beneath our couch in the front of the trailer. Next to, and under, the couch is the water pump and storage tank. Most of the plywood floor from side to side, extending out about 3' from the front of the trailer was, or had been soaked. I do not believe it has been leaking long as there is no rotting or fungus growing (just some damp, blackened plywood). I have thought all along it was the water line connections on the pump and connections to the water tank were the problem because a couple were not snug. Today I removed the vinyl from the front end to the bedroom (about half of the flooring inside--no other dampness noted).
Our Bambi is parked next to the house under a carport which makes me thank it IS the connections causing the leak. I am going to make sure my filler line and overflow tube are not leaking. Also, I am going to run a solid line from the tank to the pump. That one particular line has two elbows and a connection to the tank--all possible leak'ers.
I am certainly glad I read your post so I can include more investigating to my project. I hope this might shed some light on your project. Best....