T.F.
I would get out of the contract now.
That issue waves big red flags in my mind and you have to think about potential re-sale someday. Don't start off with a bad deal that you may never be able to sell unless you practically give it away.
You are aware of leaks and said owner says he had them fixed but something is not fixed. Run away from the deal.
There are many things to keep in mind when running a house that cost you extra money... keeping AC/Heating up to date, windows, flooring, appliances, yard, etc... You have no idea what this issue could cost you on top of the routine cost of upkeep. Plus, you would smell like the house when you go out... ugh