Legionella; compliance and mitigating risk

Lack of use of school buildings and facilities during the summer months can significantly increase the Legionella risk once the buildings become occupied again. Duty holders and responsible persons must be aware of the heightened – and hidden – risk of Legionella in water sources and systems. SOCOTEC provides some useful information on compliance and advice on how to mitigate against the risk of Legionella

To be able to flourish, Legionella needs a temperature range from 20 to 45°C – so, the warmer weather experienced over the summer period will have been an ideal environment for the bacteria to grow and multiply; with temperatures in the UK exceeding the 30°C mark this year Legionella bacteria has been provided with warmer water systems to grow in.

Empty facilities often mean a build-up of stored and stagnant water, which can become a breeding ground for the bacteria. So, showers, laundry rooms, swimming pools and other such facilities will require risk assessing and adequate servicing to ensure any risk of Legionella is managed and mitigated.

The risk of Legionella extends to hot and cold-water systems and cooling towers, as well as irrigation systems and interactive water features in public spaces. Guidance on the legislation around interactive water features can be found here. Like any other water accessory, dispenser or system, hose pipes can store stagnant water and, therefore, Legionella bacteria has the potential to grow. When next used, these hose pipes have the potential to release the airborne bacteria in tiny water droplets for inhalation, posing a risk to the user and anyone nearby.

Compliance all year round

Taking steps to keep your water systems safe should be done in line with a Legionella risk assessment. It’s not just advisory; if you are an employer, or in control of premises, you are responsible for understanding the health risks of Legionella. Failure to risk assess water systems for Legionella is punishable by fine and a prison sentence. When outbreaks occur there is a serious risk to human health, often resulting in fatalities.

Under the HSE’s Legionnaires’ disease: The control of legionella bacteria in water systems Approved Code of Practice (ACoP) L8, those responsible for health and safety must adhere to the guidance and recommendations to identify and manage the risk of Legionella in all artificial water systems.

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Control measures for safer water systems

There are several precautions to take to ensure that you minimise the risk of cases of Legionnaires’ disease, ensuring that you are compliant with HSE’s ACoP L8.

Temperature control

For hot and cold-water systems, controlling the temperatures to ensure the water is outside the Legionella growth band is vital. Keep all hot water systems at above 60°C, with water outlets maintained at a minimum of 50°C; in healthcare environments, this should be 55°C. Likewise, cold water should be kept below 20°C, wherever possible. This is not to say that Legionella is not a risk in the winter months, but water below 20oC will mean the Legionella bacteria are dormant.

Flush your systems

Water outlets that are infrequently used should be flushed regularly to avoid stagnation. Evaluating the usage of the water systems – in the Legionella risk assessment and ongoing following the risk assessment – will determine how regularly the outlet should be flushed. As a guide, any outlet that has not been used for a week or longer should be flushed for at least three minutes.

Reduce water storage

Reducing the amount of water stored will limit the stagnation of the water and reduce the potential for the growth of Legionella bacteria. If this is not possible, flushing or draining all systems will reduce the risk – and should be outlined as a control measure in the risk assessment.

Robust control measures

Where temperatures are scorching, air conditioning units are frequently used. Having appropriate control measures in place can prevent potential outbreaks from Legionella; chemical dosing, water treatment, sampling and regular maintenance can ensure water systems are safe to operate and use.

Adequate training

Ensuring staff are appropriately trained in Legionella awareness, risk assessment and their responsibilities can support effective Legionella management and control; in addition, suitable and sufficient training of all staff involved in Legionella risk management is a key requirement of the regulations.

SOCOTEC specialises in Legionella risk management and can support organisations with compliance.

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