How to Prevent Legionella Growth

Regular water quality monitoring is essential to prevent the growth of legionella. It is important to maintain records for monitoring, inspection and testing and ensure there is a clear audit trail for up to at least five years.

Building Managers and Your Responsibility for Water Quality Monitoring

Building managers are provided with a water system logbook, either a paper or an electronic version, which is used to store the records of Legionella control monitoring tasks carried out, this would include;

  • Weekly flushing of Infrequently used outlets
  • Monthly temperature monitoring from hot water generating sources and outlets (both sentinel and representative)
  • Quarterly descaling of spray producing attachments
  • Annual cold water storage tank inspection (including temperature monitoring)
  • Annual inspection of calorifiers
  • Annual servicing of thermostatic mixer valves

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    Temperature and conditions will be compared with parameters detailed in HSG274 and BS8580-1; 2019. If conditions are identified which could possibly lead to the growth of legionella bacteria then recommendations will be made to minimise the risk. Training can be given to your staff to enable them to carry out certain periodic monitoring tasks.

    What Does Water Quality Monitoring Consist Of?

    Examples of regular monitoring would be checking disinfectant and temperature levels and measuring and monitoring these parameters within the building water system to ensure it is operating the best it can to minimise the conditions that encourage Legionella.

    If findings show the control level is not being met, it is important to take corrective actions and get conditions back to an acceptable range such as ensuring water is at the highest temperature, that disinfectant levels are detectable where water enters the building and the points of use as well as measuring the pH of the water and if the disinfectant is effective.

    When carrying out water quality monitoring, it is important to pay attention to any patterns or trends found in the water parameter measurements and if anything concerning is found, that it is investigated and addressed to find the cause of the problem.

    Sometimes, this can be solved by simply flushing out low use areas or adjusting the thermostat to ensure it is outside of the 20°C to 45°C range.

    We can work with you to develop a water storage monitoring system, where we can provide water monitoring services and advise how to carry out your regular monitoring in-between appointments.

    Remote Water Tank Monitoring

    Many buildings are now installing remote water tank monitoring which is usually installed in newer buildings or can be retrofitted to most buildings. It monitors the water system temperature and can automatically flush hot and cold-water outlets.

    This clever software provides a water pump monitoring system which monitors temperature and provides flushing when required and flushes the units only when it is required – therefore saving water and energy.

    This type of water storage monitoring system measures water level parameters via sensors, allowing it to be measured remotely and automatically. However, there is two-way control if your own regular checks determine flushing is needed.

    Contact us for more information or for your FREE, no obligation quote.


    What is a water monitoring system?

    Water system monitoring consists of using sensors to measure the levels of certain elements in water. These are sent to a microcontroller board and analysed and diagnosed to highlight if these levels are outside of the parameters determined by L8.

    In the case of Legionella, temperature checks are the most commonly used way of aiming to prevent growth and it is important to ensure the hot and cold-water systems are outside of the 20°C to 45°C temperature range which creates ideal conditions for legionella to grow.

    What information can water system monitoring collect?

    The sensors can measure things such as Co2, temperature, pH and turbidity, there are reasons for these specific checks. As we know, temperature plays an important part in providing an environment for Legionella to grow – so monitoring the temperature of the water within your water storage system is vital.

    Co2 can be found in water as a dissolved gas and affects the pH of the water, leading to acidification and contributing to the corrosion of your water system. Likewise, pH needs to be measured as chlorine is often added to combat bacterial growth but if the pH is too low, this chlorine can escape as a gas, decreasing effectiveness and increasing risk of corrosion, while if it is too high then the water will not be disinfected and at risk of Legionella.

    Turbidity measures suspended solids and water clarity, the more solids in the water, the murkier it will look and is therefore a good measure of water quality. The lower the turbidity level the better.

    How often should water temperature be checked?

    If you have an automatic sensor system or remote water tank monitoring, this will likely be constantly monitored but it is recommended to complete a monthly check of the water distribution temperature and the hot water storage cylinder. For the cold-water tank, the temperature should be checked annually during the summer months where heat gain is most prominent.

    To check this, you need to turn on the sentinel outlet or tap located the nearest and furthest from the calorifier/ water heater or source by holding the tip of the thermometer tip under the running water under the water flow.

    For hot water, the thermometer should measure over 50°C within one minute and for the cold water it should record less than 20°C within two minutes. If temperatures are recorded outside of this range, it should be reported as soon as possible, and action should be taken so the growth of legionella can be prevented.

    Swiftclean Commitment:

    • FREE quotation/technical advice – Nationwide – call 0800 243 471
    • Works carried out in accordance with the Legionella Control Association (LCA) code of conduct
    • Risk Assessments and control schemes carried out to L8, BSRIA and CIBSE guidelines
    • All works fully certified and legionella control log books provided
    • Fully trained and directly employed staff
    • Method Statements and Risk Assessments provided site specific as required
    • Training for your own staff following risk assessment

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    Please call us or email for further advice and a free quote.

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