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Plastic Pipe Institute Issues Technical Note on use of PEX in Chlorinated Water

The number one job of all potable water piping systems is to keep water safe and clean for drinking. To complete this job, a pipe has to handle standard chlorine disinfection methods used in water treatment. It is well known that high chlorine content and aggressive water conditions can cause pinhole leaks and failures in copper systems, however many in the industry might be surprised to learn that PEX systems also have significant limitations when it comes to chlorinated water systems.

According to a recent technical note issued by the Plastic Pipe Institute (PPI), it was found that any combination of these factors can significantly reduce the service life of a PEX pipe. The presence of hot chlorinated water is known to cause PEX pipe to degrade causing pinhole leaks and pipe failures. For this reason, the products are tested to ASTM F2023 for chlorine resistance. Unfortunately, a listing to this standard has temperature and pressure limitations which can commonly be exceeded in certain types of construction.

According to the PPI Technical Note: “The use of PEX tubing in a potable hot-water plumbing system with an operating temperature above 140°F OR system pressures above 80psig or highly aggressive water quality OR any combination thereof can significantly reduce the service life of the tubing.”

Chlorine degradation in PEX pipe.

Comparison between new and used CPVC pipe.

While the PEX tubing may carry a temperature and pressure rating of 100psi at 180°F, the pipe is not listed to perform under those conditions in the presence of chlorinated water. These temperatures and pressures can routinely be exceeded in commercial and multifamily structures where booster pumps are required, or where elevated temperatures are specified to reduce the risk of legionella and other bacterial growth.

Even in traditional single family homes, the pressure limitation can be exceeded in certain locations with elevated city pressure. Given that pressure reducing valves can and often do fail without causing immediate problems for the homeowner, PEX tubing can be subject to pressures outside of its chlorine listing in homes as well as commercial and multi-family structures.

Under these conditions, PEX can fail rapidly – in some cases in less than 10 years after installation.

CPVC piping systems, such as FlowGuard Gold and Corzan, are immune to chlorine degradation due to the presence of chlorine in its polymer structure. This natural immunity means your CPVC system can withstand chlorinated water at the temperatures and pressures where PEX will fail.

In fact, CPVC is commonly used in municipal water treatment facilities to handle the chlorine dosing systems that ensure our water is clean and safe to drink. Even after years of exposure to chlorine, FlowGuard Gold and Corzan will never corrode, pit, scale or degrade. Homeowners, builders, and contractors can have peace of mind that they are installing a time-tested, reliable and durable plumbing system.

Since the original date of this article, Lubrizol issued this clarifying statement

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