Polybutylene is currently the subject of several class action lawsuits. The problem arises from the chemical engineers did not take into account some of the stresses seen in the real world. They could have (and I heard they did) create a better polybutylene product by adding more crosslinking (using neomers or isomers) to the molecular structure, which would also raise the density and molecular mass of the polymer.
I suggest you contact a lawyer, maybe you can get involved in one of the many class action suits underway. A lot of production scale facilities are involved in this, so I cannot venture a guess as to the identity of the company that produces it.
I also suggest you not take any legal, chemical (which these are) or a plumbing advice from a fourth year helper.
The Friendly Chemist 
[Edited by Richard on 11 January 2001]