7 Risk mitigation strategies against Legionella.
Water temperature control: How to maintain water temperatures outside of the range in which Legionella grows (typically 20-45°C).
Water treatment methods: Effective chemical and non-chemical water treatment options (e.g., chlorine, UV treatment, copper-silver ionization).
Flushing protocols: Regular flushing of taps and showers to prevent stagnant water, one of the major risk factors.
Preventive maintenance: Importance of maintaining water systems (e.g., descaling, cleaning tanks) to prevent Legionella growth.
Legionella risk assessments are a crucial part of maintaining safe water systems in facilities ranging from hospitals to hotels, as well as industrial buildings. Legionella bacteria, the cause of Legionnaires’ disease, thrives in water systems that aren’t properly maintained. A robust risk assessment will identify potential hazards, but mitigating those risks is key to preventing an outbreak.
In this blog, we’ll cover the most effective risk mitigation strategies for controlling Legionella in water systems and ensuring the safety of occupants.
1. Temperature Control: Keeping Legionella Out of the Comfort Zone
One of the primary strategies for controlling Legionella is managing water temperature, as the Legionella bacteria flourishes between 20°C and 45°C. Outside of this range, their growth is inhibited.
Hot water systems should be stored at least at 60°C (140°F) and distributed so that it reaches a temperature of 50°C within one minute at the outlets. (HSE.gov)
This ensures that any Legionella bacteria present will be destroyed.
Cold water systems should be maintained at temperatures below 20°C (68°F) to prevent the bacteria from multiplying.
Regularly monitoring and recording water temperatures is essential to verify that they remain outside the Legionella-friendly range.
2. Water Treatment Methods
Water treatment plays a critical role in controlling Legionella. There are several treatment methods, each with its own benefits:
Chlorination: The most common method, chlorine, effectively kills Legionella when used in the right concentration. Continuous dosing systems ensure that free chlorine levels remain sufficient to control bacterial growth.
Copper-Silver Ionisation: This method releases copper and silver ions into the water, which are highly effective at killing Legionella. It’s especially useful in large water systems, such as those in hospitals and hotels.
UV Disinfection: Ultraviolet (UV) light can be used to kill bacteria and other pathogens in water systems without chemicals. This method is gaining popularity in green buildings focused on sustainability.
Ozone Treatment: Ozone gas can also be used to disinfect water systems. It's powerful but may require specialized equipment and higher operational costs.
Each of these methods has different installation, operational, and maintenance costs, so the choice often depends on the size and complexity of the system.
3. Flushing Protocols: Preventing Stagnant Water
Stagnant water is a breeding ground for Legionella, especially in areas with low water use, such as infrequently used taps, showers, or sections of a plumbing system. Implementing a regular flushing regime ensures that stagnant water is cleared from the system, preventing bacterial growth.
Weekly flushing is recommended for outlets that are not in regular use.
High-risk areas, such as showers and hot tubs in hotels or hospitals, should be flushed more frequently if not in constant use.
Flushing should be combined with temperature checks to ensure that both hot and cold-water systems are maintaining appropriate temperatures.
4. Regular System Maintenance
A well-maintained water system is essential for preventing Legionella. Scale, rust, and biofilm buildup can provide an ideal environment for bacteria to thrive, so preventive maintenance is crucial.
Descaling and cleaning: Lime scale can harbour bacteria, so regularly descaling water systems, especially in hard water areas, is important.
Tank inspections: Cold water storage tanks should be inspected, cleaned, and disinfected at least annually to ensure that sediment and biofilm don’t accumulate.
Filtration systems: Installing and maintaining appropriate filters can prevent debris and other contaminants from entering the system and contributing to bacterial growth.
Additionally, cooling towers, a known source of Legionella outbreaks, require special attention. They should be cleaned regularly, and appropriate biocides should be added to the system.
5. Water Sampling and Testing
Regular water sampling and testing provide critical feedback on the effectiveness of the mitigation strategies in place. Testing for Legionella should be part of any ongoing risk management plan, and the frequency of testing depends on the nature of the building and water system.
High-risk environments, like hospitals or care homes, require more frequent testing, especially where vulnerable populations are present.
Actionable thresholds: If Legionella is detected during testing, there should be a clear action plan in place to address contamination, including disinfection procedures and retesting.
Having water treatment logs and sample test results readily available is not only important for internal safety reviews but also for meeting compliance with health and safety regulations.
6. Training and Competency Development
Even the best systems require people to operate them effectively. Training staff on how to identify potential risks, conduct system inspections, and carry out routine tasks like flushing is essential.
Appoint a Legionella Responsible Person (LRP): This individual should be trained to oversee Legionella control, ensure risk assessments are updated, and that proper preventive measures are in place.
Regular updates: Staff should be trained regularly, especially when new regulations or technologies are introduced.
Having a trained team ensures that everyone understands their role in mitigating Legionella risks.
7. Crisis Management and Response Planning
Even with thorough mitigation strategies in place, there’s always the possibility of Legionella contamination or outbreaks. Having a crisis response plan is crucial for handling any potential outbreaks quickly and effectively. It is important that the duty holder appoints a dedicated persons who looks over the risks.
Emergency disinfection procedures: These should be clearly defined and include measures like thermal disinfection (flushing with hot water) or chemical shock treatments.
Isolation protocols: In the event of Legionella detection, specific areas of the water system may need to be isolated while corrective actions are taken.
Communication plans: Informing building occupants or the public about potential risks and the steps being taken is a vital part of crisis management.
Conclusion
Mitigating Legionella risk is a multifaceted challenge that requires careful planning, regular maintenance, and a proactive approach to water management. By combining temperature control, effective water treatment, regular flushing, and monitoring, facilities can significantly reduce the risk of a Legionella outbreak.
Investing in training and a water compliance company such as Absolute water compliance can further enhance the ability to manage water systems safely, protecting public health and staying compliant with health and safety regulations. Remember, a Legionella risk assessment is just the beginning—the real protection lies in how well those risks are mitigated.
By following these best practices, building owners and facility managers can ensure that their water systems remain safe and free from the threat of Legionella bacteria. View our blog post on Legionella and our FREE Legionella template here.
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