I also have a 2000 LTV. The water lines are inside the unit and not exposed, so they are difficult to access. The water tank is the only outside exposure but is insulated. As you have probably found where the water pump is under the passenger side rear wheel housing and the winter by-pass valves are under the passenger side of the sofa bed behind the removable panel. That is about all of the water lines you will find exposed except under the sink for the faucets. Not the easiest to trouble shoot, but when they build these things they start with bare walls and everything is built in to fit.
Good luck with whatever you are up to.
Barry
