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How Do You Test For Legionella?

The Legionella bacteria is commonly found in water systems and can cause Legionnaire’s Disease – a severe form of pneumonia. This can have potentially fatal complications within the human lungs. The disease is not contagious, but it is quite easily contracted when contaminated airborne droplets are inhaled into the lungs.

Therefore industrial and commercial water systems need to be subject to a legionella risk assessment with testing carried out by a competent professional. Together, these two actions combine to identify areas where a proliferation of legionella bacteria exists and what controls can be put in place to make the systems safe to use. Ongoing testing and monitoring is then essential to comply with ACoP L8 standards.

Harmless levels of legionella bacteria can be found in mains water-supplied drinking water, so it is important that high risk areas are identified and attention is focussed on them. These tend to be low temperature water in hot water systems, which are conditions known to be a good breeding environment for the bacteria.

Where should I test for legionella?

In general, however, the legionella bacteria should be tested for where:

  • A water system is being treated with biocides
  • Hot water is stored or distributed at lower temperatures
  • You can’t consistently achieve a certain temperature or disinfectant concentration in a water system
  • In healthcare premises or care homes, or any place where there is a higher risk or susceptibility
  • Any water system where there is a suspected or identified outbreak of legionella.

Under COSHH regulations any organisation where there is a risk of the legionella bacteria developing must:

  • Carry out a legionella risk assessment
  • Prepare a scheme for preventing or controlling the spread or risk of legionella
  • Appoint a person to have managerial responsibility
  • Implement control measures identified in the risk assessment
  • Keep ongoing records

What controls help prevent legionella build-up?

The controls to be implemented in managing the outbreak of legionella include the following:

  • Controlling water temperatures (typically hot water systems should be 50°C or higher and cold water systems should be 20°C or lower)
  • Remove dead ends from pipework and systems to prevent the build-up of stagnant water
  • Flush out and clean systems periodically (recommended to be quarterly)
  • Monitor for signs of corrosion in pipework
  • Test water samples regularly

How to test for legionella

Testing should be in accordance with BS7592 and taking samples from previously-identified high risk areas. You should collect water samples and surface swabs and take the samples to a UKAS-approved laboratory for reliable results. It can take a period of time (sometimes up to two weeks) to get a full result as the lab has to allow the organism to grow on an inoculated plate).

Robinsons Facilities Services can carry out your full legionella control for you, as we work with accredited and experienced professionals who can carry out your risk assessment and ongoing monitoring. This includes carrying out on-site testing and ensuring your ongoing compliance, via regular cleaning of your systems and the dosing of biocide disinfectants which help to prevent the growth of the bacteria.

Contact us today and we can carry out a site visit and agree a schedule and a price for your ongoing legionella controls.


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