Water systems in commercial environments must be tested regularly to ensure they are free from harmful bacteria like Legionella. When a positive test result for Legionella is received, immediate and effective action is crucial to prevent potential health risks. Here’s how to effectively manage Legionella positives and safeguard your water systems.
What is a Legionella Positive?
A Legionella positive occurs when the bacteria Legionella is detected in a water system during routine testing. When Legionella is detected, your water hygiene provider will alert you with a Legionella-positive result. A water sample is tested for the bacteria, if the bacteria is detected in your water system, the testing lab will send across a legionella positive. At this point, immediate action should be taken. This includes reviewing temperature control measures, biocide levels, and ensuring the cleanliness of your water system. Regular testing of water systems is crucial for ensuring safe water quality and preventing outbreaks.
In the UK, every water system used in a business environment should be risk assessed to determine where the legionella risks lie. A Risk Assessment of your water system will assist in mitigating risk and detecting where there may be a potential risk of legionella. Preventative measures are usually documented in risk assessments and addressed by the responsible person. A disused piece of pipework (dead leg) can be removed to eradicate the risk it poses. Or, a rarely used yet still operational shower head can simply be flushed through regularly to reduce risk!
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Managing a Legionella Positive
If you receive a Legionella positive result, it’s essential to act quickly. Here are the best strategies to manage the situation effectively:
Flushing the System
Undertaking a safe Legionella flushing regime and maintaining good water hygiene records will ensure the bacteria does not proliferate. Flush infrequently used outlets to reduce the risk of Legionella daily. Perform intensive cleaning and maintenance where required. Flushing the water system is one of the most effective ways to reduce Legionella growth. Keep shower heads and taps free of mold, algae, and limescale. Periodically clean tanks with chlorine solution and drain them to remove sediment and scale. To prevent water stagnation, shorten pipe lengths and remove unused pipework. Quick Tip: After periods of non-use, such as holidays, run showers and taps for at least 5 minutes to clear out stagnant water and prevent bacteria growth.
Temperature Control and Disinfection
Thorough disinfection and flushing are essential steps in managing a Legionella positive. Legionella can be disinfected using both thermal and chemical methods. Heating water to 70°C for at least three minutes or up to 2 hours, can kill bacteria effectively. Regular dosing with biocides will keep your water systems clean and safe! Add a biocide to the water system at a controlled dose, and open taps and outlets to allow the disinfectant to reach every part of the system. Quick Tip: Ensure your system receives consistent disinfection treatment to minimise the risk of future outbreaks.
Filtration for Added Protection
Adding point-of-use filters to outlets like showers, sprinklers, or hot tubs can reduce the risk of Legionella by preventing bacteria from spreading through aerosolised water droplets. This is to keep water in use and turning over. Remove the outlet(s) from use; undertake a similar or more extensive re-sampling programme in the short term. We suggest prohibiting the use of, or fit point of use filters with 0.2µm membranes to all aerosol outlets.
Re-sampling and Ongoing Testing
Once a Legionella positive test occurs, re-sampling helps ensure that your water management measures are working. Consistent testing will also identify any recurrent issues within the system. By tracking results, you can adjust your control measures proactively. Review previous and subsequent results for further failures; and take further pre-and post-flush samples from a representative number of outlets on the same system and/or in the same area to identify the source of the contamination. Check if the positive results are coming from the same locations. This might indicate a persistent problem in specific areas of the water system.
Reviewing and Strengthening Control Measures
Implement a water management program to control the growth and spread of Legionella. Conduct a risk assessment for all systems that use or store water. Keep a record of all precautionary measures and control treatments. The responsible person must ensure that staff are appropriately trained to manage and control the risks posed by Legionella. If the control levels in the water treatment program (temperature or chemical concentrations) are not met, a thorough review and appropriate actions are necessary. Conduct frequent Legionella testing, initially weekly, to ensure system control. Once under control, review the testing frequency. Review the effectiveness of control measures that have been implemented in the past. This includes temperature control, biocide use, and regular flushing of the system.
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Legionella Management Solutions
We provide comprehensive Legionella control services that fit your needs. Don’t wait until it’s too late—contact Legionella Management Solutions today to keep your water systems safe and compliant. Whether you need routine testing, emergency response, or ongoing maintenance, our team is ready to help.
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