Controlling Legionella bacteria in water systems

The Health and Safety Executive's Approved Code of Practice (ACOP) L8 provides guidelines for controlling Legionella bacteria in water systems. A critical aspect of these guidelines is ensuring that hot water outlets reach a temperature of 50°C within one minute (30 seconds Water Regulations). This rapid temperature increase is essential for preventing the growth of Legionella bacteria, which can lead to Legionnaires' disease.

Legionella and its risks

Legionella bacteria thrive in water temperatures between 20°C and 45°C. If inhaled through water droplets, they can cause Legionnaires' disease, a severe form of pneumonia. Therefore, maintaining water temperatures outside this range is crucial for safety.

Regulatory requirements

ACOP L8 mandates that hot water should be stored at 60°C and distributed at 50°C or higher. This ensures that any Legionella bacteria present are killed or prevented from multiplying. The guidelines also emphasise the importance of regular temperature checks and system maintenance to ensure compliance.

Technical implementation

To achieve the required temperature at outlets, several technical measures can be implemented:

• Setting the temperature: Ensure that hot water cylinders are set to maintain water at 60°C. Regular checks and maintenance are necessary to prevent temperature drops where applicable.

• System design: Use thermostatic mixing valves to manage outlet temperatures, especially where there is a risk of scalding. These valves should be installed close to the point of use.

• Regular flushing: Outlets that are not frequently used should be flushed regularly to prevent stagnation and temperature drops.

Monitoring and maintenance

Regular monitoring and maintenance are crucial to ensure compliance with ACOP L8:

• Temperature checks: Conduct regular checks of outlet temperatures to ensure they reach 50°C within the specified time. This includes both routine checks and additional checks after any system changes or maintenance.

• Record keeping: Maintain detailed records of temperature checks, maintenance activities, and any corrective actions taken. This documentation is essential for demonstrating compliance during inspections.

Conclusion

Reaching 50°C at outlets within 30 seconds to one minute is a critical requirement of ACOP L8 to control Legionella bacteria. By implementing proper system design, regular maintenance, and diligent monitoring, facilities can ensure compliance with these regulations, thereby safeguarding public health. In a domestic dwelling, it is important to follow the Water Regulations which stipulate 50°C at each outlet within 30 seconds, emphasising the importance of safety, efficiency and comfort.

LEGIONNAIRE'S DISEASE

Find more information and download the Approved Code of Practice and guidance here.