Assuming yours is a polyethylene tank: I had a small crack / leak at the outer base of a fitting (threads were still ok). I took the tank to a large RV repair shop and they had a plastic welder of sorts and fixed it for good for about a half hour labor charge. Depends on the access to the crack but something to consider. If you do have to replace it, take it from someone who cruises with a wife and two daughters: the bigger the tank, the better.... Definitely replace hoses while its out and if you install new fittings, the smooth -surfaced type rather than the barbed type are worth finding - hoses go on and off with a lot less swearing.'Hope this helps.