I recently moved into a house, that had been re-piped with Polybutylene back in the 80's..... I had a plumber replace it all with PVC up to the house from water meter, then CPVC under the house (his recommendation) This was strictly because insurer would not cover house for water damage, until PB was all replaced..... when I researched this issue, the sites I found said that it was NOT the PB that was the issue, it was the copper/brass tees / couplers / etc, that corroded and failed, (it was mentioned that at least *some* manufacturers sourced them from CHINA.......) Also, if you google PEX, this has also been an issue for *SOME* brands of PEX (metal connectors corroding and failing, over time)