Jonathan Simon, Lubrizol Advanced Materials Inc.
Table of Contents
For decades, plumbers debated the merits of copper vs. plastic piping for hot and cold-water distribution piping. Today, copper piping is gone from residential new construction, but the industry still struggles to differentiate quality between the commonly used plastic piping systems. When it comes to the critical duties of reliably delivering clean, safe drinking water and driving sustainable building practices the differences between other plastic piping and CPVC can be like night and day.
Water Disinfectants and Plumbing Systems
CPVC has a leg up on other plumbing materials in its ability to handle disinfectants currently added to potable water because CPVC is a chlorinated compound and water treatment practices in the U.S. are dominated by the use of chlorine-based disinfectants.
Being a chlorinated material makes CPVC plumbing systems immune to degradation from chlorine-based disinfectants currently used in drinking water in normal conditions, which is important for multiple reasons. First, it allows CPVC to perform reliably at its rated temperature and pressure in the drinking water. That is not always the case with other plastic plumbing systems. According to the Plastics Pipe Institute (PPI) Technical Note 53, titled “Guide to Chlorine Resistance Ratings of PEX Pipes and Tubing for Potable Water Applications”, these plumbing systems can be subject to accelerated chlorine degradation at temperatures above 140° F and pressures above 80 psi.
The other benefit of CPVC’s immunity to chlorine disinfectants in drinking water is its ability to deliver reliable performance in aggressive water conditions, which are becoming more common. The Oxidation Reduction Potential (ORP) of residential drinking water, a key indicator of the aggressiveness of water on vulnerable plastic piping materials, is influenced by multiple factors, including the disinfectants added to the water to make it safe. Higher ORPs (above 825 mV) have been identified in PPI TN-53 as another factor that can accelerate chlorine-related degradation in PEX systems.
Issues related to aggressive water conditions exist in many other plumbing piping materials, including copper, polypropylene (PP-R and PP-RCT), PE-RT and galvanized iron. Plumbers simply have no way to protect vulnerable pipes from aggressive water conditions. Municipalities regularly change the amount or type of disinfectant used in response to multiple factors that can affect water quality, often driving up ORP in the process. One of the changes being made today, which should be of particular concern for plumbers, is the increased use of chlorine dioxide. While chlorine dioxide is not aggressive to CPVC at temperatures up to 200° F, research has shown that this disinfectant has the potential to reduce the service life of many other piping materials. Multiple manufacturers now recommend against the use of their products “as part of any potable-water distribution system in buildings where chlorine dioxide is used for secondary disinfection.”
Plastic Piping and Water Quality
The chemistry of the piping systems also comes into play in protecting water quality and a plumbing system’s ability to resist waterborne bacteria.
Biofilm is a risk to water quality because it can contain harmful bacteria such as E. coli, coliforms and legionella. The measure of how susceptible a material is to biofilm growth is called its biofilm formation potential. Independent researchers have found that CPVC piping consistently has a comparatively low biofilm formation potential. That can translate to a reduced risk of harmful bacteria in drinking water. A controlled study conducted by Kiwa, a respected international testing and inspection institute, found the amount of legionella growing in CPVC piping to be significantly lower than in other materials studied (Figure 1).
In addition, CPVC is compatible with common bacterial mitigation and remediation techniques, including storing and distributing hot water above 140° F (before mixing down the temperature closer to the point of use), shock chlorination, and use of chlorine dioxide in legionella mitigation programs.
CPVC’s chemistry also allows the material to resist chemicals from permeating the pipe and entering the water supply. The U.S. EPA, in its study on Permeation and Leaching, found that vinyl like CPVC are virtually impermeable at low levels of exposure, and at high levels of exposure would fail before allowing the water to become contaminated. That same study found that 82% of documented permeation incidents in the United States at the time occurred in piping materials from the polyolefin family of plastics.
Research from Virginia Tech has found that CPVC plumbing systems have the lowest impact on drinking water taste and odor. Additional data published by NSF, has found that other piping materials are capable of leaching MTBE, ETBE, TBA and Toluene and can not only affect drinking water taste and odor, but may also exceed the limits set by some state public health officials.
Plastic Piping and Sustainability
The sustainability of a plumbing material is influenced by its embodied energy, longevity and recyclability.
CPVC has a lower embodied energy than the other leading plumbing materials. According to data in the National Institute of Standards and Technology (NIST) Building for Environmental and Economic Sustainability (BEES) database, a CPVC plumbing system emits nearly 1 ton less carbon into the atmosphere than a PEX plumbing system over the life of a small house.
Longevity influences sustainability because the longer a product can perform in its intended environment, the less material is ultimately required to support the application. Plumbing materials that are vulnerable to degradation from the chlorine-based disinfectants used to keep drinking water safe can suffer leaks that shorten their life. CPVC’s immunity to degradation from water treated with chlorine-based disinfectants increases the likelihood that the system will achieve a long life and not need premature replacement.
For projects seeking LEED or NGBS certifications, FlowGuard Gold CPVC has a lifecycle assessment, which contributes to LEED credits. FlowGuard Gold CPVC is also the only residential plumbing system certified by Home Innovation Labs National Green Building Standard (NGBS), which identifies products that have been independently verified to improve environmental impact measures and support project certification under ICC-700 National Green Building Standard.
The Right Choice for Plumbers and Builders
Water quality and sustainability are factors plumbers should consider when selecting materials, since they are important to homeowners and builders. FlowGuard Gold CPVC delivers superior performance in the areas plumbers care most about: speed of installation, overall quality, and reliability. For more information, visit flowguardgold.com.
Lubrizol Advanced Materials, Inc. (“Lubrizol”) hopes that you have found the information provided helpful, but you are cautioned that this material, is for informational purposes only and you are solely responsible for making your own assessment of appropriate use of the information. Any material will react with certain chemicals in different ways according to concentration levels, temperatures, pressures and the nature of the material. Performance is subject to proper manufacturing and installation of pipes and fittings and use according to manufacturer’s guidelines. Lubrizol does not guarantee how the materials referenced herein will perform in combination with other substances, in any methods, conditions, or processes, with any equipment, or in non-laboratory environments.
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Jonathan Simon is the North American residential plumbing manager for Lubrizol Advanced Materials Inc., the parent company for FlowGuard Gold Pipe and Fittings.
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