Chlorinated polyvinyl chloride (CPVC) is a thermoplastic produced by chlorination of polyvinyl chloride (PVC) resin. Uses include hot and cold water pipe, and industrial liquid handling.
Polyvinyl chloride is produced by polymerization of the monomer vinyl chloride (VCM), as shown. Since about 57% of its mass is chlorine, creating a given mass of PVC requires less petroleum than many other polymers. It can be made softer and more flexible by the addition of plasticizers, the most widely-used being phthalates. In this form, it is used in clothing and upholstery, and to make flexible hoses and tubing, flooring, to roofing membranes, and electrical cable insulation. It is also commonly used in figurines and in inflatable products such as waterbeds, pool toys or jump houses.
I am not a fan of CPVC or PVC. PVC (polyvinyl chloride) plastic is manufacturered with poisonous chemicals such as mercury, dioxins, and phthalates, which may cause cancer and harm the immune and reproductive systems.
I have no PVC pipe in my home. Use at your own risk. To each his own.