Secondary disinfection: What it means to your piping system
Many factors contribute to the design and specification of a piping system, from size to pressure to layout. It’s just as critical to think about what’s inside the pipes — the quality of the water and the disinfection treatments that will be used on that water over the life of the system. The additives used for primary and secondary disinfection can often have an impact on the integrity of the pipe.
For the majority of projects, water only undergoes treatment at a central location through the water district. But it’s important to know that, for many project types, additional treatment may be necessary at the building location. Secondary disinfection is becoming more and more popular at hospitals and healthcare settings, as well as other buildings in which a vulnerable population may be present. In many instances, hospitals can’t use water straight from the municipality because it may still contain levels of many harmful bacteria that either doesn’t get removed in the primary process or that enters the water system afterward. To ensure the water is safe for the more vulnerable occupants and highly sensitive materials, it will undergo secondary disinfection on site prior to widespread distribution.
“Primary disinfection kills or inactivates bacteria, viruses, and other potentially harmful organisms in drinking water,” the EPA says. “Secondary disinfection provides longer-lasting water treatment as the water moves through the pipes to consumers.”
There are a range of methods for secondary disinfection. Common and very effective are chlorine dioxide generators, which are capable of eradicating many remaining bacteria; the use of chlorine dioxide requires a worker who is certified with its use and safety requirements. Chlorine dioxide is a residual treatment, which means it stays in the system over a period of time. Another option is a UV generator, which may be less effective because it relies on every microorganism passing within the UV light. Other examples include chlorine, copper-silver ions, hydrogen peroxide, ozone, peracetic acid and peroxide.
Each method has its positives and negatives. The upcoming revised version of the ANSI/ASHRAE 188 Guideline will help engineers and facility managers understand each method to help determine what method is the best fit for each project.
Pipe material and secondary disinfection
No matter which type of secondary disinfection is used, it’s crucial for engineers to determine what the facility is planning to use before specifying the type of pipe materials. Simply put: Not all pipe materials can withstand all types of disinfection methods.
When exposed to high concentrations of chlorine dioxide, Corzan CPVC does not pit or develop pinhole leaks over time, and thus does not carry with it a disclaimer about such interactions in its manufacturer’s warranty. Because CPVC inherently has lots of chlorine atoms attached to and surrounding its chain structure, it has inherent resistance to degradation by chlorinated water. Unlike other types of plastic pipes, it does not rely on sacrificial antioxidants to protect itself. Antioxidant additives act as a sacrificial barrier against degradation. They protect non-chlorinated plastics not only against aggressive chemicals like chlorine in the water, but also against free radicals that occur naturally within the polymer upon exposure to heat or light.
If a building is likely to use secondary disinfection methods, Corzan CPVC offers the greatest peace of mind to engineers and facility managers. To learn more, contact one of our specialists today.
Jeff Ramey has nearly 30 years’ experience in the plumbing industry, having worked closely with engineers, designers, distributors, code officials and contractors to provide technical product training on water and gas and fire sprinkler piping systems. He is a member of major plumbing, engineering and fire sprinkler associations, including AFSA, ASPE, ASHRAE, NFSA and is a voting member of ASHRAE Technical Committee 3.6, Water Treatment and TC 8.6, Cooling Towers as well as a non-voting member of SPCC 188, Legionellosis: Risk Management for Building Water Systems. Jeff has presented countless technical sessions on all aspects of water and gas piping systems, with events at local and national levels including PHCC, ASPE, ASHRAE and more. In addition, Jeff has written contributing articles published in trade publications.