Legionella On Board Trains: On Track for a Safe Water Supply

Posted by David Heuston on 28-Oct-2016 09:13:27
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David Heuston, environmental field team leader, Environment & Safety services, SOCOTEC, explores the risk of legionella in water systems on board trains, and explains what rail operators need to consider to ensure they offer the safest possible environment for passengers and workers.

More commonly associated with water systems within buildings, legionella bacteria can also grow in the water tanks and plumbing on board trains, making it a health and safety concern for rail operators in the UK. The organism thrives in water temperatures of between 20°C and 45°C, meaning that the storage and distribution of water on warm trains brings an increased risk of bacterial growth.




Legionella is a pathogenic bacterium and, if inhaled via water droplets, can cause the pneumonia-like infection known as Legionnaires’ disease. More than 371 confirmed cases of Legionnaires’ disease were reported in the UK in 2015, making it a significant health issue across the country.


With the health implications of legionella in mind, rail operators have a duty of care to take action to minimise the risk to workers and passengers by managing the potential for bacterial growth across its operations.



Understanding the risk

Due to their nature, train units provide a number of unique challenges to rail operators in terms of minimising legionella risk. As well as toilets, many intercity trains also contain catering facilities, and each of these is fed by separate on-board water tanks. For hygiene reasons, and to protect against contamination, these tanks are designed to be completely sealed except for an inlet valve, any outlets and an overflow on the underside of the carriage.


The sealed nature of the design means that the tanks themselves are difficult to access for cleaning, and as a consequence, limescale and sediment can accumulate over time. Without regular monitoring and, if required, cleaning and disinfection, conditions in the tank can become ideal for legionella bacterial growth.


In addition, the water tanks are often situated immediately under the roof of the carriage, an area that can become very warm. This means that, under direct sunlight, the water can quickly reach the ideal temperature range in which legionella thrives.  As a result, unless steps are taken to minimise the risk of the bacteria being present in the system, it can very quickly become a potential health risk.



Meeting regulations

Due to the potential risk of legionella growth on board trains, operators need to ensure they comply with existing guidance to safeguard the health and wellbeing of workers and passengers.


The key pieces of regulation that operators need to comply with are the Health and Safety Executive’s (HSE) L8 Approved Code of Practice (ACoP) and Guidance on Legionnaires’ disease, and the supporting HSG 274 technical guidance on the management of legionella risk.


Both documents contain guidance and recommendations for those responsible for health and safety to adhere to in order to maintain safe water systems. By following the advice set out in both documents, rail operators can significantly minimise the risks posed by legionella to their employees and passengers on board their trains.



Taking action

The HSE’s L8 ACoP L8 regulation stipulates that all legionella risks must be identified and managed.  For rail operators, this means regular monitoring and maintenance of all water systems on board trains, while cleaning and disinfection may also be required. Keeping the stored water below 20°C and flushing the system frequently will help to reduce biofilm and sediment build-up in the tanks, reducing opportunities for the bacteria and other organisms to grow.


How regularly these tasks need to be carried out will depend on the findings of a legionella risk assessment of the on-board water systems. Once an assessment has been made, operators must then put in place a programme of tasks within their written scheme to ensure water systems remain in an acceptable condition. The frequency of flushing, inspection and cleaning may also vary according to the particular requirements of the rolling stock in question.


Regular sampling of on-board water systems will help to confirm if the control measures in place are effective. As explored in our recent blog, Legionella Control in the Rail Industry: Keeping Risk Management on Track, the water should also be maintained safely in supply tanks, and can be tested at carriage tanking facilities at the railway depot before it is pumped on board the train. Taking these steps will help operators minimise the risk of Legionella entering their trains’ water systems in the first place.



Talking to experts

Putting the right processes in place will ensure operators are able to uphold optimal levels of health and safety for their employees and passengers while they are travelling on their trains.


However, there is considerable variety in terms of the rolling stock in operation on the UK rail network, with a range of train types built at different periods and by different manufacturers. The water systems of each unit will have its own unique design features, which could pose specific challenges for legionella management.


By working with Legionella management experts, operators can ensure they have access to advice and guidance tailored to the unique needs of their rolling stock. With this support, they can make sure they provide the safest possible environment for both their workers and their passengers, not just in their stations and other buildings, but on board their trains as well.


If you would like more advice about managing legionella on board trains, please contact us at [email protected]


Topics: Rail, Legionella