Here are sources of information on why polybutylene piping used in house plumbing is bad:
http://www.sfloridahomeinspection.com/polybutylene-piping-realtors-beware/embed/#?secret=lYgWdNWYpA
Polybutylene Piping: Concerns, Risks, and Resolutions
Be informed about a home’s plumbing system before you buy.
http://porch.com/advice/polybutylene-piping-concerns-risks-resolutions/
Polybutylene pipes—found during a home inspection
http://www.zillow.com/advice-thread/Polybutylene-pipes-found-during-a-home-inspection/39636/