By now most people are aware of the dangers in polybutylene water lines. If not, not a bad idea to google it. There has been issues with the fittings and internal corrosion that led to several Class Action Lawsuits with a settlement pool for over 21 million homes nationwide.
Few people are aware, however, of a similar issue with the replacement version of polybutylene, called PEX; a plastic water line typically white, blue or red. The primary culprits was a fitting manufactured by Zurn (model F1807) as well as one manufactured by Nibco.
The issue arose from an excessive amount of zinc used in the manufacture of their brass fittings. The chemicals used to treat water has a tendency to corrode these fittings, leading to either their failure at the fitting site or buildup of corrosion on the interior of the pipe, leading to poor water pressure.
If you believe you have PEX, check out the fittings prior to an issue. It's worth a few minutes of your time, to prevent water damage.
For more details on how to file a claim, or gather more info, contact https://sagewater.com/nibco-pex-lawsuit-class-action-settlement/ or https://www.classaction.org/pex-plumbing-lawsuit
Zurn Brass Fitting Model F1807 Internal buildup caused by brass fittings