Chlorinated Polyvinyl Chloride (CPVC) Water Supply Piping

Chlorinated polyvinyl chloride (CPVC) is a thermoplastic pipe and fitting material approved for potable water distribution in all fifty states. It is an off-white rigid material and installs using fittings made from the same material bonded in place with a solvent.

CPVC has been used successfully in residential, commercial, and industrial applications for nearly 50 years. It is most commonly used in single-family and multi-family hot and cold water distribution systems. However, it can be used for residential fire sprinkler systems, chemical drain waste systems, and industrial processing. CPVC key advantages include its resistance to corrosion, pitting, and scaling, ease of installation, and light weight.

Though PVC and CPVC belong to the plastics family and possess similar core materials, they perform very differently. The chlorination process used in making CPVC gives the material its superior performance in both high temperature and high pressure applications. The extra chlorine molecule makes CPVC very difficult to burn. CPVC will not sustain a flame on its own as there is not enough oxygen in the atmosphere to make it burn. When the flame source is removed, CPVC will self-extinguish. Additionally, CPVC should not be confused with polybutylene piping, which suffers from reliability issues because it could react unfavorably to some elements in various water systems.

	CPVC piping may be a more affordable alternative to copper piping systems, reducing the overall cost for the homeowner.
	There is less heat loss from CPVC than from metallic pipe, making for a more energy efficient supply water system.
	CPVC is popular in places with more aggressive soil and/or water conditions (e.g. coastal areas) because it will not pit or corrode regardless of the pH level in the water. Quieter operation is one of the primary benefits realized with CPVC pipe and fittings. Since CPVC is more flexible than metallic pipe, the exterior wall of the pipe can expand slightly and absorb water flow noise, resulting in a significantly quieter operation.

Initial Cost  

The labor savings afforded by a CPVC system will vary depending on the size and complexity of the project. Some contractors have documented as much as a 50 percent labor savings as a result of switching from copper to CPVC. This savings is attributed to the fact that CPVC is joined using a fast and easy solvent cement process which replaces the more time-consuming task of soldering. CPVC is also lighter in weight than copper (approximately one-sixth of the weight) so it is easier to maneuver on the jobsite.

Operational Cost  

A CPVC plumbing system should cost the same to operate as any other piping material in the same layout (e.g. trunk and branch). However, a CPVC system can save money if a leak occurs or reconfiguration is needed. CPVC piping is easy to work with and does not require specialized tools, soldering, or welding.

Although local plumbing codes may vary with regard to installation and testing requirements, CPVC is approved for hot and cold potable water use in all 50 states. Some jurisdictions, such as California, have restrictions on the use of CPVC. California has a "findings requirement" where a determination must be made that indicates the water will likely cause corrosion or copper pinholes.

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CPVC piping is joined using a fast and easy solvent cement for joints which does not require torching or soldering. Installers can use a fine-tooth saw to cut CPVC and sand paper to remove any burrs prior to joining. Circular tubing cutters with a plastic cutting blade and ratchet cutters are very efficient. Care must be taken in temperatures less than 50oF when using a ratchet cutter, as the pressure could cause pipe walls to crack. CPVC supply water systems typically follow a trunk and branch layout. After installation, the pipes are secured to the studs or supports with hangers. CPVC should be secured every three feet horizontally according to the IPC.

Pressure testing can be done once the solvent cement has reached the recommended cure time. The cure time is based on product and ambient temperature, but in some installations pressure testing can be done in as little as 90 minutes.

CPVC can be used in under-slab applications. This is the predominant plumbing method in Florida. Due to the solvent cement joining process, the joint of a CPVC plumbing system becomes the strongest part of the system and is more durable than either the pipe or fitting alone. Newer technologies have allowed for bendable CPVC to be manufactured, which is convenient for underslab applications.

When connecting CPVC to a gas water heater, use at least six inches of metal pipe or appliance connector so that the CPVC tubing is not damaged by build-up of excessive heat from the draft diverter. Some high-efficiency direct-vent gas water heaters eliminate the radiant heat from the flue and can be piped directly to the water heater. CPVC can be piped directly to an electric water heater. A brass-threaded CPVC transition fitting is recommended for these applications. Note that some code jurisdictions require metal connections on all water heaters. Verify code requirements prior to installation.

CPVC can be used as the water heater discharge lines as well. It is approved for this application by all major plumbing codes, including the Standard Plumbing Code.

Some manufacturers offer warranties dependant on proper installation of CPVC piping, ranging from 6 months to the duration of the original owner’s ownership of the property.

CPVC piping offers a rigid piping system that many builders and plumbers are accustomed to without the risks of corrosion, pitting, scaling, and pinhole leaks that can occur in copper installations when local water or soil conditions are less than favorable. CPVC pipe is generally cheaper than copper piping as well. Its cost, ease of workability and its durability make it an economical choice. CPVC piping is also an energy efficient choice, since less heat is lost as hot water moves through the pipes. It can be a quieter option for homeowners as well, as the structure may reduce water hammer.