I think the filter media would take a few days for the bacteria to die off. Not sure on that, but I don't think they're that delicate.
I will say that the leaking is the fear I try to ignore, but always comes up. My 75 gallon tank is on the 2nd floor and on wood. If I had a bad leak there it would be disastrous. I've thought about getting some of those things that can detect water, but haven't pulled the trigger. I mostly stick my head in the sand and hope for the best.
I did have a 10 gallon downstairs where the HOB filter leaked. I stuck a Nitrazorb packet in the filter and some of that fuzzy filter stuff (what's it called? My head is not working). Anyway, it was too much and the filter was silently dripping down the back. Luckily my fish room is also what my wife, for some reason, calls the "laundry room" and it has tile floor (with cement underneath), so no real damage. It just made my wife paranoid about the one upstairs.
Of course, I was saying, "no, Sweetie, it'll be fine, I'm using all the best equipment, blah blah." She's right to worry though.
Do any of you use any detectors to sound an alarm if they get wet?