Previous water leak/damage not revealed at closing

The answer is as equally frustrating as it is tricky.  Whether or not you have a claim and against whom comes down to particulars.  First off, you have to figure out who (or who all) is at fault.  For example, if you are looking at the sellers - what did they know and what did they say?  Could the inspector have missed something? Could the realtor or broker have breached a duty?  The questions are too numerous for the forum, but the point being that if the details line up, you could have a claim.  It generally comes down to what you can prove was known, what was revealed, and what opportunities you had to find out.  If you are interested in pursuing legal action, your best bet is to sit down with an attorney to look at the documents and discuss the details.