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Legionella Water Testing & Risk Prevention
Legionella bacteria can thrive in water systems if left unchecked. Our testing service identifies potential risks and helps you prevent outbreaks in various settings, including workplaces, healthcare facilities, hotels, and more.
Legionnaires’ disease control and prevention
Legionnaires’ disease is a severe pneumonia caused by the Legionella bacterium.
People may become infected when they inhale aerosols from a contaminated source.
People can contract the disease from places like hotels, hospitals or offices where the bacteria have colonised the water supply.
You can also be exposed to the bacteria that cause Legionnaires’ disease from things like:
- air conditioning systems and cooling towers
- processes using water sprays or mists
- humidifiers
- spa pools and hot tubs
- taps and showers that are infrequently used
Early symptoms of legionnaires’ disease
Clinically it is a serious condition and has a mortality rate of around 12% of cases so prevention is certainly recommended.
Whilst treatment is available for those who are infected, there are direct duty of care and legal implications for all managers and persons holding responsibility for the health and safety of their employees or the public. Consequently prevention of Legionella should be regarded as an essential task.
Legionella legislation your statutory obligations as a duty holder
As a duty holder, you have a legal duty to carry out a risk assessment to identify and assess whether there is a risk posed by exposure to Legionella from the hot and cold water system or any work associated with it. The following briefly describes the obligations of a building operator or owner.
A Health and Safety Executive (HSE) leaflet briefly defining your Legionella obligations is downloadable from the HSE website. It provides basic common sense advice.
The Health and Safety at Work etc. Act 1974
- Sections 2, 3, 4 and 6 are defined within ACoP L8 as applicable to legionella control. The first 2 sections cover the primary requirements for most operations.
The Management of Health and Safety at Work Regulations 1999 (MHSWR)
- These regulations provide a broad framework for controlling health and safety at work. As well as requiring risk assessments, they also require employers to have access to competent help in applying the provisions of health and safety law; to establish procedures to be followed by any worker if situations presenting serious and imminent danger were to arise; and for co-operation and co-ordination where two or more employers or self-employed persons share a workplace.
The Control of Substances Hazardous to Health Regulations 2002
- Regulations 6, 7, 8, 9 and 12 are particularly relevant to Legionella control.
- Regulation 6, Assessment of the risk to health created by work involving substances hazardous to health, is perhaps the most relevant.
- Legionella bacteria are classified as substances hazardous to health and therefore a Legionella risk assessment can be considered a mandatory requirement in all workplace buildings with water systems.
The Notification of Cooling Towers and Evaporative Condensers Regulations 1992.
- This regulation requires the registration of evaporative cooling devices.
Specific guidance with regard to the control of Legionella bacteria is supplied in the following HSE documents:
- Approved Code of Practice and guidance L8 - Legionnaires’ disease - The control of Legionella bacteria in water systems.
- Legionnaires’ disease - Part 2: The control of Legionella bacteria in hot and cold water systems (HSG274).
These documents can be used as guidance on the tasks and responsibilities that are applicable to the water systems on your site.
Further guidance is available on:
- Control and maintenance of water system affecting Legionnaire’s disease from Health and Safety Executive (HSE)
- Legionella and the prevention of legionellosis from WHO, 2007
- Legionella and other infectious agents in spa-pool systems from Health and Safety Executive (HSE)
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Effective Treatment Strategies for Safer Systems
We tailor water treatment methods to fit your facility’s specific needs. From chemical dosing to filtration and softening, each strategy targets safety, efficiency, and regulatory compliance.
For buildings hot and cold water systems
Water services should be operated at temperatures that prevent Legionella growth:
- Hot water storage cylinders (calorifiers) should store water at 60°C or higher
- Hot water should be distributed at 50°C or higher (thermostatic mixer valves need to be fitted as close as possible to outlets, where a scald risk is identified)
- Cold water should be stored and distributed below 20°C
A competent person should routinely check, inspect and clean the system, in accordance with the risk assessment.
Stagnant water favours Legionella growth. To reduce the risk you should remove dead legs/dead ends in pipe-work, flush out infrequently used outlets (including showerheads and taps) at least weekly and clean and de-scale shower heads and hoses at least quarterly. Cold-water storage tanks should be cleaned periodically and water should be drained from hot water cylinders to check for debris or signs of corrosion.
Design systems to minimise Legionella growth by:
- keeping pipe work as short and direct as possible;
- adequately insulating pipes and tanks;
- using materials that do not encourage the growth of Legionella;
- preventing contamination, e.g. by fitting tanks with lids and insect screens.
Additional controls
Water samples should be analysed for Legionella periodically to demonstrate that bacteria counts are acceptable. The frequency should be determined by level of risk, in accordance with the risk assessment.
Other control systems
Other methods to control Legionella include biocide treatments. AWT favour our proven Chlorolox technology which can safely treat water and reduce Legionella risk.
For any system to remain effective their application will need suitable assessment as part of the overall water treatment programme including proper installation, maintenance and monitoring. AWT offers full service and support for all our dosing and control systems.
AWT design build and install treatment systems for a wide variety of systems including cooling towers and industrial plant using water.
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