If you are looking for a home, DO NOT buy one with Polybutelane pipes. Polybutelane pipes react and corrode when it comes in contact with chlorine. The danger here is the chlorine will eat away at the pipes until it makes its way through. It is not a matter of "if", it is a matter of WHEN. If you have Polybutelane pipes, you will have leaks.
If you already own a home and it has these pipes, there is a class action lawsuit you can get in on and try to get money to replace EVERY pipe in your house but chances are you will only receive a fraction of the total costs.