Testing For Legionella: What’s Involved?

Legionella is a common and potentially deadly bacteria found in many industrial water systems, such as evaporative cooling systems and hot and cold water systems. Nominated people and facilities managers have a duty to manage their water systems and their associated risks, with a view to monitoring and preventing the build-up of legionella bacteria.

There are essentially three parts to the legionella testing that an organisation has to carry out, and the first part of this, a legionella risk assessment, essentially dictates the frequency of the remaining two stages. Spring 2014 saw the release of a new approved code of practice detailing the requirement for ‘regular’ legionella risk assessments. This frequency had previously been every two years, but a legionella risk assessment remains a legal requirement, and this assessment effectively dictates the regularity of the further testing you need to carry out.

Legionella Risk Assessment

A legionella risk assessment looks at your system design, its component parts, pipework and biocides used and evaluates the risk of each element. This needs to be carried out by a responsible person, who is trained, competent and has the responsibility to suitably carry out the exercise and provide informed analysis and outcomes. In some cases this will be done by a third party contractor, where internal resources aren’t available or competent.

While the new guidance states risk assessments should be carried out ‘regularly’, there should be a set frequency of less than every two years, in organisations deemed as high risk. These include premises where:

  • Elderly people or people with relevant health issues are present
  • There are changes made to the system design
  • New information is published or updated
  • The current process is no longer deemed as being effective
  • A legionella outbreak is suspected or out of norm samples have been recorded.

Testing Requirements

Once the risk assessment has established a testing frequency, this regime shall then be immediately implemented. This frequency depends on the type of water system in place and the risks involved, plus what other monitoring and control measures are in place, but essentially, the testing is split into two parts:

  1. Routine testing carried out by the responsible person (internal if resources allow) to monitor and test the water in the system for evidence of the conditions in which legionella bacteria is likely to grow. This could be a weekly test, and should monitor the temperature of the water. Legionella bacteria typically thrives in temperatures between 20-45?C, with optimum growth averaging at around 37? This should therefore be checked regularly, as specified by the risk assessment, to identify conditions where the risk increases.
  2. Testing for the presence of the legionella bacteria requires the technical expertise of a third party water hygiene company, who will test water samples to BS7592, neutralise the biocide used and utilise a UKAS accredited lab for the analysis. This can be done on-site or off-site but results are required swiftly to allow remedial action where required. Again, the frequency of this testing is dependent on the risk assessment outcome, but is usually less frequent than the water temperature testing.

All tests, whether carried out internally or externally should be recorded as a historical reference point. This data can then be used when updating the risk assessment, to add weight to changing or maintaining the current testing frequency. Of course, Water Hygiene Services have qualified engineers capable of acting as your responsible person, and carrying out all risk assessments and subsequent monitoring, testing and analysis regimes. So call us today or fill in our enquiry form and we can discuss your system design and your testing requirements going forward.