Doin' the Full Monte

[Jim & Susan]

Ok Guys, We bought a '73 Overlander a couple of months ago. We've decided to do a complete renovation. We have all of the interior out from the bath forward (rear bath). We knew going in that there was a problem with the water system. The PO had pulled a new water line from the back of the coach to the galley area. We hadn't had much of view until today when we started gutting things for real.
For whatever reason, the PO has completly bypassed the holding tank and was apparently using just city water. We have not had the opportunity as yet to completely look at the hot water tank situation. I do know that it works, at least in some rudimentary way.
Here's the thing. In removing the stove/sink/galley area, and accessing the holding tank area underneath, a truely WEIRD smell seems to be coming from the holding tank. It smells almost like evergreen (Pinesol?) or possible some other cleaning agent. It really makes you think that the fresh water holding tank has been contaminated in some way. We are new to the RV world (but not to camping). Is ther any possibilty that this is just the smell of some sanitizing agent or should I not take the chance and "spend the bucks, do it right the first time" and buy a new one.
After spending many hours on the forum over the past few months, i know someone will have an answer. Appreciate help in advance. Jim