How Do Piping Materials and Water Temperature Affect Legionella Growth?

As independent Legionella consultants who find the best, most cost-effective Legionella control solution for our clients, we carefully follow the latest Legionella research. Our independence means that we don’t offer just one solution for Legionella, and new research often contains new ideas we can turn into practical solutions. Below is an example of useful Legionella insights.

A study of drinking water distribution systems (DWDSs) found that both the material composition of pipes and water temperature are critical factors that influence the microbial communities in the water.

The study focused on three different pipe materials:

• galvanized steel
• copper
• cross-linked polyethylene (PEX)

• 72°F
• 90°F

The study lasted six weeks and analyzed the microbial and elemental contaminants.

The study found the following:

• Species richness (alpha diversity) was also affected, with the PEX systems being the least diverse, followed by steel and copper systems. (From the aspect of control or mitigation, lower microbial diversity is presumed to be better because the environment is generally less hospitable to bacteria and other opportunistic waterborne pathogens. Therefore, PEX would be preferred, followed by steel, and then copper.)
• The study also revealed that higher water temperatures decreased species richness. (Similarly, given that from the aspect of control or mitigation, lower microbial diversity is presumed to be better. However, as noted in this Legionella Control Systems article on the Legionella risk factor of temperature, both of the temperatures used in this study fall within the Legionella growth range, so neither temperature is preferred for Legionella control.)
• Legionella was found to be present across all systems.
• Mycobacteria, another bacterial family, were more prevalent at the elevated temperature of 90°F (100% vs. 59%).
• Pseudomonas, a group of bacteria that includes some pathogenic species, were more prevalent at the lower temperature of 72°F (53% vs. 63%).
• Higher water temperatures resulted in well-defined microbial clusters within all systems. The most significant impact was observed in the PEX system, followed by copper, and steel systems.
• The findings suggest that Legionella and Mycobacteria are more likely to thrive in warmer water environments.

The results indicate that water temperature substantially impacts the microbial composition more than the pipe material in drinking water distribution systems.

As a Legionella expert, Legionella Control Systems has the unique ability to understand and provide advice on key Legionella factors, as well as Legionella remediation and mitigation strategies. Not all companies have our independence, so you can trust Legionella Control Systems to recommend the best Legionella control approach for your particular situation.

View our industrial Legionella control systems and our industrial Legionella control and management services. Legionella Control Systems also provides Legionella risk assessment and Legionella testing. For more information on our Legioneall consulting or testing, contact us at 317-934-6833 or info@legionellacontrolsystems.com.