Plastics Pipe Institute Evaluates Impact of Chlorine Dioxide on Plumbing Materials

Over the last few decades, the US EPA, CDC, and independent researchers have published information related to the potential risks associated with disinfection byproducts, which can form when bacteria in drinking water interact with chlorine and chloramine water disinfection. As a result of this research, water utilities have begun to consider chlorine dioxide (ClO2) as a method which may be less likely to form potentially harmful byproducts and has been shown in research to be effective in treating water-borne viruses.

Some newer municipal water treatment facilities and those undergoing modernization have installed equipment for chlorine dioxide treatment. In addition, chlorine dioxide is increasingly being used in nursing homes, hospitals and other facilities to treat or control pathogens such as legionella. Comparing CDC and American Water Works Association (AWWA) estimates of chlorine dioxide usage over time shows that usage appears to have nearly doubled in the last 20 years.  

In addition to being a highly effective method of water treatment, chlorine dioxide can be aggressive to several types of plumbing materials. As a service to the industry, the Plastics Pipe Institute (PPI) has conducted an extensive analysis of published research on the impact of chlorine dioxide on plastic piping. The results are summarized in Technical Note (TN) 67: Chlorine Dioxide and Plastic Hot- and Cold-Water Plumbing Distribution Pipes.

Key Statements from PPI TN-67

The following quotes were taken from PPI TN-67:

• PPI’s investigation into this topic has found that multiple research teams around the world have performed various types of laboratory testing to evaluate the effects of chlorine dioxide on piping materials of copper, steel, PEX, PE-RT, and PP-R…
• …the published results indicate that chlorine dioxide has the potential to reduce the service life of most plumbing distribution materials to below normal expected lifetimes.
• Evaluation by PPI member firms indicates that chlorine dioxide is not known to be aggressive to CPVC at elevated temperatures of 200°F (93°C) and below. 
• PPI recommends contacting each piping system supplier for guidance related to the use of their pipe and fitting material(s) in circumstances where chlorine dioxide has been selected as the disinfection chemical. 

Plumbing System Manufacturer Guidance on Chlorine Dioxide

PPI’s membership includes many of the leading manufacturers of plastic piping systems, so it’s no surprise that pipe and fitting suppliers both agree with TN-67 and have updated their design and installation instructions accordingly.

Leading PEX manufacturers such as Uponor* and Viega* now advise against the use of their products with chlorine dioxide: 

• “Uponor does not recommend use of its PEX pipe and ProPEX fittings as part of any potable-water distribution system in buildings where chlorine dioxide is used for secondary disinfection…”
• “Viega LLC does not recommend use of Viega PureFlow PEX tubing as part of any potable water distribution system in buildings where chlorine dioxide is used as a secondary disinfection…”

The FlowGuard Gold CPVC team concurs with the PPI statement that chlorine dioxide is not aggressive to FlowGuard Gold CPVC at temperatures of 200° F or below. In fact, FlowGuard Gold and Corzan CPVC are the only plumbing systems marketed today as 100% immune to chlorine degradation caused by drinking water in domestic plumbing systems. 

Real-World Implications

While PPI TN-67 notes that use of chlorine dioxide as a secondary disinfectant does not reflect the majority of current water disinfection practices, failures of plastic pipe have already been attributed to the disinfectant in at least one municipal water system.

After switching to chlorine dioxide for secondary water treatment, the city of Hamilton, Ohio, experienced high rates of failure in its high-density polyethylene (HDPE) water mains. These failures occurred in cold water HDPE systems; the higher temperatures found in hot-water lines can make the degradation reaction even more aggressive in vulnerable polyolefin systems like PEX, PE-RT, PPR, and PP-RCT.

“We’ve got about 21 miles of HDPE piping in our system now, and it is catastrophically failing, about 60 years ahead of when it should have,” the city’s Executive Director of Infrastructure, Jim Logan, told the local Journal News. “This, back about 20 years ago, was the future of water mains, and unfortunately, the chemicals we use attack the pipe and then cause it to fail.”

This city’s experience reinforces both the risks to some materials from incompatible chemicals like chlorine dioxide as well as the difficulty predicting future water conditions at the time materials are selected and installed. Municipalities can and do change their treatment practices for a variety of reasons and there is no way to ensure that pipes installed today won’t at some point be exposed to water treated with chlorine dioxide. 

Mitigating the Risk of Changing Treatment Practices

Builders and plumbers can’t control or predict whether pipes are exposed to chlorine dioxide, chloramines, or chlorine—all of which can shorten the life of PEX plumbing systems. The only sure-fire way to protect against premature failure caused by incompatibility with these disinfectants is to choose a material that is immune to degradation and corrosion from all three when used in potable water systems. That material is FlowGuard Gold CPVC.

Download our submittal specifications and compare them with any PEX manufacturer to learn more about the differences between CPVC and PEX.

*Updated as of June 2024