CPVC pipe

Entry in PEX and plastic supply pipe · Updated October 29, 2026 · Written by the Know Your Pipes editors from the sources listed under References

CPVC pipe is rigid plastic water pipe made from chlorinated polyvinyl chloride, a PVC that has been further chlorinated so it can carry hot water under pressure.^[1] It was introduced for drinking-water plumbing in 1959 and is accepted in all of the model plumbing and mechanical codes for hot and cold water, fire protection, chilled water and hydronic heating.^[1]

The house-plumbing form is CPVC tubing made to ASTM D2846, which shares outside diameters with copper tube.^[1][2] CPVC is also made in iron pipe sizes from 1/2 in to 24 in, in Schedule 40, Schedule 80 and SDR wall types, mainly for commercial and industrial work.^[1]

1 Material

CPVC is made by adding chlorine to PVC in a water slurry or fluidized-bed reaction started by ultraviolet light, then compounding the result for pipe.^[1] The extra chlorine raises its temperature limit and improves its fire and chemical resistance compared with PVC Schedule 40, which is not used for hot water.^[1] The Plastics Pipe Institute calls CPVC immune to chlorine degradation, even at temperatures up to 200°F.^[1]

2 Sizes and ratings

Water-distribution CPVC is made in 1/2 in to 2 in nominal sizes to SDR 11, so its wall is about one-eleventh of its outside diameter and every size has the same pressure rating.^[1][3] Standard hydrostatic ratings are 400 psi at 73°F and 100 psi at 180°F.^[1] One manufacturer's specification limits its system to pressure service at no more than 180°F at 100 psi.^[2]

Dimensions from one maker's installation guide.^[3] The outside diameters are the same as those of copper tube of the same nominal size.^[1][3]

3 Joining

CPVC is joined by solvent welding: a cement that meets ASTM F493 softens the pipe and fitting socket so they fuse.^[2] Some cements are labeled "one-step" and may be used without primer; two-step cements require primer, and one maker's specification calls for ASTM F656 primer where local code requires it.^[2][3] Joints need cure time before a pressure test, longer in cold weather.^[3]

Threaded and compression connections to metal need care. One installation guide recommends transition fittings for all hot-water connections and says plastic male threads are not recommended on hot lines because temperature swings can cause a drip leak.^[3] See transition fittings.

4 Handling and installation limits

CPVC is rigid and lacks the mechanical strength of metal, so it should not be stepped on or have objects dropped on it.^[3] Some chemical products damage it, including certain fire-stopping materials, thread sealants and plasticized vinyl products, so makers ask for compatible products only.^[2]

Sunlight is another limit. One maker advises covering stored pipe with a non-transparent material and applying latex paint to any CPVC installed outdoors.^[3] More is in sunlight and UV limits.

CPVC expands about 4 in per 100 ft for a 100°F temperature rise, so straps should hold it loosely and long hot runs need offsets.^[3] The same guide calls for supports every 3 ft on horizontal runs of 1 in and smaller and every 4 ft on larger sizes.^[3] At a gas water heater it calls for at least 6 in of metal nipple or connector between heater and CPVC; some jurisdictions require metal connectors on electric heaters as well.^[3]