Bathroom

You step out of the shower onto a partially-wet bath mat. The damn thing is always damp, because the towel rails are always full. So you end up hanging the mat over the top of the shower to dry, but it never seems to fully dry by the next morning.

Maybe you got distracted by the latest episode of Desperate Housewives and the bath overflowed. Or maybe your dishwasher hose sprung a leak whilst you were at work. Some reasons for flooding the house are preventable, some aren't.