Legionella bacteria, responsible for Legionnaires’ disease, can grow in water systems such as hot and cold water, cooling towers, and other stored or recirculated water sources. Effective management is critical for protecting health, complying with the Health and Safety at Work etc. Act 1974 and meeting the requirements of the HSE’s Approved Code of Practice L8.
Key Control Strategy
A robust legionella management programme should include the following elements:
Risk Assessment
- Identify all water systems where legionella could grow.
- Assess risk based on water temperature, storage, stagnation, and biofilm presence.
- Review the likelihood of aerosol generation and potential exposure to occupants or staff.
Water system controls
- Temperature Control: Maintain hot water ≥ 50°C in storage and ≥ 60°C at outlets; cold water ≤ 20°C where possible.
- Avoid Stagnation: Remove dead legs, regularly flush unused outlets, and ensure circulation in pipework.
- Disinfection & Treatment: Use biocides, chlorine, or alternative chemical treatments as per risk assessment.
Routine monitoring and inspection
- Check water temperatures at regular intervals.
- Inspect storage tanks, pipework, showers, and cooling towers for cleanliness and scale.
- Maintain records of all monitoring, inspections, and corrective actions.
Cleaning and maintenance
- Regularly clean tanks, showerheads, and outlets to prevent biofilm and scale build-up.
- Service and maintain pumps, filters, and cooling towers according to manufacturer guidance.
Training and awareness
- Ensure staff responsible for water systems understand legionella risks, control measures, and reporting procedures.
- Train cleaning and maintenance personnel on safe procedures to minimise exposure.
Contingency planning
- Develop procedures for system contamination, unusual bacterial growth, or outbreak scenarios.
- Include steps for disinfection, notification of authorities, and temporary closure if required.
Benefits of a strong legionella control programme
- Protects employees, residents, and visitors from serious illness.
- Demonstrates regulatory compliance under HSE L8 guidance and COSHH where applicable.
- Reduces legal, reputational, and operational risk associated with legionnaires’ disease.
- Supports proactive maintenance and long-term water system efficiency.
A well-structured legionella management plan combines risk assessment, temperature control, routine maintenance and staff awareness to minimise risk and maintain compliance.
