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How to identify Legionella Sampling Points

How to Find Legionella Sampling Points

The need to test water systems for the presence of legionella is well understood. However, as you plan for a Legionella Risk Assessment, it’s not enough to run a faucet and jump into testing. Finding the appropriate legionella sampling points is the difference between dangerous legionella going undetected and achieving compliance.

But how do you know where to test? Where is legionella most likely to exist in your hot and cold water systems? And how can an experienced team help you get accurate results from your tests?

Test for poorly controlled temperatures

Bacteria only grows in specific circumstances. Temperatures that are extremely cold or hot are an ongoing deterrent for legionella – but the middle ground is where you could find yourself exposed.

Legionella bacteria thrives in temperatures between approximately 20°c and 50°c. As a result, it’s crucial to test those areas where water temperatures are hard to control. This could include long stretches of pipework where heated water can cool.

In addition, there may be instances where water is intentionally heated to within this range. Sampling at these points is essential.

Finally, it’s important to be aware of changing conditions throughout the year. The hot summer weather can have a significant impact on temperature control, creating a subtle increase that allows bacteria to proliferate. At these times, more regular testing may be necessary.

Test for pollutants and sediment build-up

As water flows around your hot or cold system, there are numerous variables that can affect the condition and temperature of your water. Any build-up starts a dangerous cycle that can promote the growth of legionella bacteria.

First, sediment can lead to the growth of seemingly-unrelated microorganisms like algae and flavobacteria. In turn, these will provide nutrients to legionella, helping the bacteria colonise your entire system.

Meanwhile, build-ups may impair the performance of existing disinfectants and other water hygiene processes. Sampling where build-ups are likely will highlight potential issues and risk levels effectively.

Test where water may become stagnant

Fast-moving water being continuously circulated around your system is a difficult place for legionella to take hold. Bacteria breeds in those places where water sits stagnant for weeks, months, or even years on end.

Typically, we see significant risk in storage tanks, calorifiers, low usage outlets and little or infrequent used showers, these are the places where legionella can really take hold – and another key location to sample as part of your legionella risk assessment.

Sample water consistently and continually and monitoring trends.

As you search for the signs of legionella growth, there are numerous places you should sample water to achieve accurate results. However, this is just the start.

Beyond the initial sampling, the HSE advises that testing should be carried out in a UKAS-accredited lab in accordance with the latest standards. Then, it’s vital that you regularly revisit and re-test your water, sampling from the same points to preserve the integrity of your results and check trends. You will also need to increase the frequency of your sampling when your risk is highest, for example when hot weather increases water temperature.

Of course, this makes effective legionella control an ongoing, hard-to-manage task. That’s why we provide all-encompassing Legionella Risk Assessments designed to help you meet your legal obligations long-term.

As trusted partners, we’ll work with you to:

  • Conduct a precise risk assessment with accurate sampling from the most appropriate points
  • Document your risk levels for compliance
  • Recommend next actions and provide building hygiene log books
  • Regularly revisit your testing every two years as a minimum

With clear guidance from the Health & Safety Executive as well as numerous well-publicised outbreaks, the need for accurate legionella sampling is clear.

Keep your water systems compliant while drawing on our proven experience, specialist expertise, and accredited lab. 

Visit our website to learn more about our Legionella Risk Assessments.

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