Updated Guidance on Legionella Control in Evaporative Cooling Systems: What You Need to Know

   06 June 2024         News

The Health and Safety Executive (HSE) has recently released an updated (second edition – March 2024) version of HSG274 Part 1, focusing on the control of Legionella bacteria in evaporative cooling systems. This update brings crucial enhancements to the existing guidelines, ensuring better management of Legionella risks in these systems.

What’s New in HSG274 Part 1?

The update to HSG274 Part 1 includes significant improvements in several key areas related to managing the risk of Legionella in evaporative cooling systems:

  1. DPD No 1 Testing Methodology: The revised guidance provides more detailed information on the DPD No 1 testing method, a widely used technique for measuring the concentration of free chlorine in water. This method is essential for ensuring that cooling systems are dosed correctly with biocides.
  2. Impact of pH on Biocide Efficacy: The updated guidance highlights the importance of cooling water pH in determining the effectiveness of halogen-based biocides such as chlorine and bromine. Maintaining the correct pH levels is vital to ensure these biocides can effectively prevent the growth of Legionella bacteria.

Many organisations rely on these tests to confirm proper biocide dosing. Correcting the pH of free-halogen test results is a crucial step in verifying that sufficient biocide is present in the system to inhibit Legionella growth. It’s essential to review your latest test results to ensure they are pH-corrected.

Expert Insights

Dan Sutherland, Senior Trainer for Develop’s Legionella/Water Systems division, emphasised the importance of these updates:

Where the HSE identifies areas of concern and ways in which measures can be improved; notification, understanding, implementation, and management are crucial. Our industry is an evolving one. It goes without saying that control of water chemistry is key for evaporative cooling systems for the control of microbial growth, fouling, scale, and corrosion.

On a personal note, I think all of the industry is pleased that the ball has started to roll on rapid sampling for Legionella – through quantitative polymerase chain reaction (PCR). Keep an eye out for changes afoot for Legionella guidance on hot and cold water systems and other risk systems; these changes will all be incorporated into Develop’s training material so you can rest assured the training you receive from us will always be current and up to date with the latest legislation.”

Staying informed and implementing these updated guidelines is critical for ensuring the safety and efficiency of evaporative cooling systems. By doing so, organisations can better protect against the risks associated with Legionella bacteria.

Accessing the Latest Legionella Guidance

The latest editions of the HSG274 guidance documents can be downloaded for free from the HSE website at: www.hse.gov.uk/legionnaires/technical-guidance.htm

If you have any questions about legionella and water systems please contact our Customer Service team on 0800 876 6708 or email enquiries@developtraining.co.uk.

Alternatively, you can view our full range of Legionella and Water Systems training on our website here: https://www.developtraining.co.uk/training/estates-and-facilities-management/water-systems-legionella/

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