What is the Difference Between CPVC and PVC?

The main difference between CPVC and PVC lies in their chemical composition and temperature tolerance. Both PVC (polyvinyl chloride) and CPVC (chlorinated polyvinyl chloride) are thermoplastic materials used for piping systems, but they have distinct properties:

Chemical Composition: PVC is a man-made thermoplastic composed of hydrogen, carbon, and chlorine. CPVC is produced by chlorinating PVC, which increases its chlorine content from 56-57% to 63-67%.
Temperature Tolerance: CPVC can handle temperatures up to 200°F (93°C), while PVC peaks at 140°F (60°C). Above these temperatures, both CPVC and PVC may soften, increasing the risk of joint failure and plumbing system failure.
Flexibility: CPVC is more flexible than PVC, which means it requires support at three-foot intervals to maintain its position.
Nominal Pipe Sizes: PVC comes in nominal pipe sizes only, while CPVC is available in both nominal pipe sizes and copper tube sizes.
Pressure Ratings: The pressure ratings for PVC and CPVC change dramatically with temperature, so it is essential to consider temperature tolerance when choosing the right material for a specific application.
Cost: PVC is generally less expensive than CPVC, with PVC costing around $0.40/ft (Schedule 40) and $0.52/ft (Schedule 80), while CPVC costs around $2.50/ft (Schedule 40) and $3.02/ft (Schedule 80).

Due to their different properties, PVC and CPVC are recommended for different applications. While both are suitable for water, gas, and drainage systems, many plumbers recommend CPVC for hot water lines and PVC for cold water lines. It is not recommended to mix PVC and CPVC pipes and fittings, as it can compromise the pipe line's temperature and pressure ratings.