We live in Pittsburgh and we have a basement, which means that we have water in that basement. This is especially unsurprising since there is a big hill behind the house and it's easy to see how water can come down the hill and collect in the ground in the backyard when it rains.
When we first looked at the house there was some mold in one corner of the basement, so we had the sellers pay for a contractor to come in and get rid of the mold and clean up the little bit of water damage that there was.
We figured that would be that. But no, several weeks later we came back to look at it again, and there was water in the same corner. This time the sellers agreed to pay for a contractor to put in a drain all along the back wall of the basement to carry any water that came in over to the sump pump.
Since then we have not had any more water, but we'll see what happens in the Spring when the snow melts. So far we have been extremely lucky that all that happened before we closed and the sellers agreed to pay for it.