How to Prevent Legionella Growth in Water Systems This Summer

The days are getting longer, and the temperature is starting to rise as we head towards summer. However, for those in charge of maintaining water systems, the warmer weather also brings a pressing concern: Legionella bacteria. This pathogen thrives in warmer temperatures, which makes it essential to stay vigilant and take steps to prevent contamination in your water systems. 

The Summer Heat and Legionella

While many of us enjoy the hot weather, it's the perfect environment for Legionella to thrive. This bacteria causes Legionnaires' disease, a potentially fatal form of pneumonia, particularly for those with pre-existing health conditions. Legionella flourishes in water temperatures between 20°C and 45°C, meaning that as the weather heats up, so too does the risk of an outbreak.

Public Health England's Legionella Surveillance Reports have shown a noticeable spike in cases from July to October since 2017, and this trend is almost certain to reoccur in 2025. Several factors contribute to this increase: from warmer outdoor temperatures to water systems left stagnant during the off-season, or even travel-related transmissions. Whatever the cause, the summer months demand extra attention to prevent Legionella from finding a home in your water systems.

The Risks of Summer

Many institutions, such as universities, schools, and accommodations, often remain vacant during the summer, leading to stagnant water in their systems. This can create the perfect breeding ground for Legionella. Similarly, tourism venues like holiday parks and water resorts, which are less frequently used during the cooler months, face similar risks when the water is left standing without adequate monitoring.

The summer often sees a rise in staff absences, which can impact maintenance and oversight of water safety. Reduced staffing can make it more difficult to maintain proper control measures, putting both your system and the people who use it at risk.

Your Duty as Duty Holder

As we move through the summer months, it’s more crucial than ever for Duty Holders to stay on top of water system maintenance. It's your responsibility to regularly inspect and maintain the water systems in your properties, keeping an eye on temperature levels to ensure they remain safe and fall within regulated guidelines. Keeping thorough records and reporting any issues promptly is a key part of the responsibility.

Duty Holders should follow the legal frameworks designed to minimise the risks of Legionella:

• The Health and Safety at Work Act 1974

• The Management of Health and Safety at Work Regulations

• Control of Substances Hazardous to Health (COSHH) Regulations 2002

• HSE Guidance: Legionnaires' Disease: The Control of Legionella Bacteria in Water Systems (ACoP L8)

By staying informed and proactive, you can keep your water systems safe and compliant, minimising the risks of Legionella and other waterborne pathogens.

How To Safeguard Your Property This Summer

1. Regular Temperature Monitoring: Check water temperatures regularly to ensure they do not reach the 20°C–45°C range, which is ideal for Legionella growth.

2. Avoid Stagnation: If your buildings or facilities are vacant during the summer, ensure the water systems are flushed regularly and the water is circulating to avoid stagnation.

3. Train Your Staff: With potential summer absences, it’s vital to ensure that enough trained staff are available to monitor and maintain your water systems. Consider one of our Legionella training courses. 

4. Professional Help: If you’re unsure of how to maintain compliance or control Legionella risks, don’t hesitate to consult professionals such as SMS Environmental. We can assist with water system inspections and treatments, ensuring your systems are safe throughout the year.

If you have concerns or need further assistance with Legionella control, our team is ready to help. Please call 0800 138 21 21 or use the contact form.