How UV Light Affects Plastic Plumbing Materials

Ultraviolet (UV) light can originate from sunlight or fluorescent light bulbs and is an aggressive oxidizer. In humans, UV light is responsible for sunburns; in plastics the effects of UV depend on the type of plastic. Plumbing systems can be exposed to UV light during the storage, transportation and installation of plumbing materials.

While the manufacturer’s original packaging should be UV protective, products are not always shipped to the jobsite in their intact, original packaging. That’s why it is important to understand how UV light affects the performance and lifespan of the materials you are using. 

PEX and UV Light

With PEX, the oxidizing effects of UV light can significantly affect the performance and lifespan of PEX piping. UV light consumes the chlorine-inhibiting antioxidants that protect the pipe from chlorine-induced oxidation and premature failure. As these chlorine inhibitors get consumed, the piping is left vulnerable to attack from chlorine in the water. With prolonged exposure, UV light may damage PEX piping even without the presence of chlorine.

Depending on the type of PEX being used, as few as 30 days of UV light exposure can reduce the expected lifespan of the material by at least 21% when exposed to chlorinated water conditions.

And sunlight isn’t the only enemy of PEX piping. At least one PEX manufacturer advises against installing PEX piping within 5 feet of direct view from fluorescent and LED lighting without protecting the pipe with a UV-blocking material.

FlowGuard Gold CPVC and UV Light

While prolonged UV exposure is not recommended, FlowGuard Gold CPVC will not experience diminished pressure-bearing capacity or expected service life due to exposure to UV light. FlowGuard Gold CPVC that has been exposed to UV light for extended periods will continue to meet the material’s temperature and pressure specifications of 100 psi at 180° F and 400 psi at room temperature.

Long-term exposure to UV light can result in some discoloration and reduced ductility of the material. When servicing CPVC pipes, regardless of UV exposure, use a C-style tubing cutter, a fine tooth saw or a wheel cutter. Ratchet cutters are not recommended for servicing CPVC piping. 

Make the Safe Choice

UV light can have negative effects on both CPVC and PEX piping materials, but UV exposure will not cause spontaneous failures in a FlowGuard Gold plumbing system. With PEX, UV light exposure destroys the material’s chlorine-inhibitors, leaving the pipe more vulnerable to chlorine degradation and may significantly reduce the service life of the piping.

Exposure to UV light before materials reach the job site is beyond the control of the plumbers doing the installation, and even after installation pipes can be exposed to UV until the building envelope is fully closed. With FlowGuard Gold CPVC, you don’t need to worry about piping failures caused by UV exposure. Download our brochure to get the facts about FlowGuard Gold CPVC vs. PEX.