The presence of Legionella in water systems – whether that’s in buildings or on board trains - is a serious issue, as it has the potential to cause Legionnaires’ disease.
To be able to flourish, Legionella needs a temperature range from 20-45°C – so warmer weather tends to create an ideal environment for the bacteria to grow and multiply. That is not to say, however, that Legionella is not a risk in the winter months. Although dormant at temperatures below 20°C, Legionella bacteria are still present, ready to multiply when optimum conditions are restored. As the winter approaches, SOCOTEC has some advice on what steps should be taken all year round to protect against the bacteria flourishing in your water systems.
Any number of water systems within a rail depot, outbuildings and lineside facilities can be affected by Legionella. All water facilities require risk assessing and adequate servicing to ensure any risk of Legionella is managed and mitigated.
In the depot, emergency showers, old sinks in disused outbuildings, redundant hose pipes as well as train wash systems can be considered risk areas - especially if there are any water outlets that have reduced usage in winter, as Legionella thrives in stagnant water. Upon use, those systems have the potential to release the airborne bacteria as tiny water droplets, posing a risk to the user and anyone nearby that may inhale them.
Water storage tanks and hot / cold water systems can also become a breeding ground for the bacteria - both on board rolling stock and in the depot.
Adhering to guidance
Even beyond seasonality, the risk of Legionella extends to any hot and cold water system including cooling towers and heating systems.
Taking steps in keeping 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. Failures to risk assess water systems for Legionella is punishable by fine and a possible prison sentence. Legionnaires’ disease is a serious infection that can result in death so identifying and managing the risk is essential.
The HSE’s Legionnaires’ disease: The control of legionella bacteria in water systems Approved Code of Practice (ACoP) L8, outlines what rail operators responsible for health and safety must do to manage the risk. They must adhere to the guidance and recommendations to identify and manage the risk of Legionella in all artificial water systems.
Control measures for safer water systems
To minimise the risk to workers and passengers, there are a number of precautions to take to help minimise the potential risk of bacterial growth. These precautions will also ensure you are compliant with HSE’s ACoP L8.
Control the temperature
For hot and cold water systems, controlling the temperatures to ensure the water is outside of the Legionella growth band is vital. Keep all hot water systems storing at or above 60°C, with water outlets maintained at a minimum of 50°C. Likewise, cold water should be kept below 20°C, wherever possible.
Flush systems regularly
Water outlets that are infrequently used should be flushed to avoid stagnation. If there is any doubt over the use of an outlet, flush it. Emergency showers and tanking points are good examples of possible infrequently used outlets. By evaluating the usage of the water systems (in the Legionella risk assessment and ongoing following the risk assessment), you can determine whether an outlet requires flushing or not. As a guide, any outlet that has not been used for a week should be flushed for at least three minutes.
Reduce the amount of water stored
Even more effective, reducing the amount of water stored will limit the potential for stagnation and reduce the potential for the growth of Legionella bacteria. If this is not possible, flushing or draining all systems will reduce the risk by reducing the build-up of sediment and biofilm. Any system taken off line for longer than a month must be cleaned and disinfected before going back into use.
Appropriate control measures
Having appropriate control measures and monitoring in place can prevent potential outbreaks from Legionella. In addition to temperature and flushing, chemical dosing, water treatment, sampling and regular maintenance can ensure water systems are safe to operate and use.
Water tanks on board trains should be completely sealed, with the exception of an inlet valve, any outlets and an overflow. Restricted access makes for difficult cleaning, meaning that – without regular monitoring - the uncleaned water can become an ideal environment for legionella bacteria to thrive. Regular sampling of on-board water systems will help to confirm if the control measures in place are effective.
Provide staff with adequate training
Ensuring staff are appropriately trained in Legionella awareness, risk assessment and their responsibilities can support in effective Legionella management and control. Understanding the importance of completing certain tasks can ensure staff are mindful of their duties in making the safest possible environment for workers and passengers.
Not only that, suitable and sufficient training of all staff involved in Legionella risk management is a key requirement of L8.
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