I'm at my parents' house, trying to fix some plumbing problem. The bathroom is down the hall and on the left, and there's this drain that's like a huge well, about 10 feet deep and three or four feet across, square. There is a drain hole at the bottom which I think is the problem, and I think by putting some water in there, it might push through. So I fill it up, but... it doesn't work, it just fills up. There are a couple of chains attached to the floor at the bottom, maybe they have something to do with it? Then it starts to overflow, and in an adjacent room there is suddenly a couple inches of water. I turn it off, but it starts somewhere else, and I just can't stop it.