I'm considering purchasing a townhouse built in 1998 where the seller's disclosed that polybutlene pipes would be replaced before settlement. During the inspection the inspector only saw cooper inside the house. However, the seller's have hired a contractor to replace the outside pipes that lead to the house with a copper system. Apparently, there is a leak somewhere because the sump pump was continously running during the 2 hour inspection. Is it possible to have polybutlene outside and not inside the house? Also, if there were previous leaks in the house, what type of damage may have been caused, that would have not been picked up by the inspection? Should I just run? By the way, the house backs to a lake. Could this be an added risk factor?