plumber at work making the consumption metering

Updated Guidance on Legionella Control in Evaporative Cooling Systems: What You Need to Know

   06 June 2024         News

The Health and Safety Executive (HSE) has recently released an updated (second edition – March 2024) version of HSG274 Part 1, focusing on the control of Legionella bacteria in evaporative cooling systems. This update brings crucial enhancements to the existing guidelines, ensuring better management of Legionella risks in these systems.

What’s New in HSG274 Part 1?

The update to HSG274 Part 1 includes significant improvements in several key areas related to managing the risk of Legionella in evaporative cooling systems:

  1. DPD No 1 Testing Methodology: The revised guidance provides more detailed information on the DPD No 1 testing method, a widely used technique for measuring the concentration of free chlorine in water. This method is essential for ensuring that cooling systems are dosed correctly with biocides.
  2. Impact of pH on Biocide Efficacy: The updated guidance highlights the importance of cooling water pH in determining the effectiveness of halogen-based biocides such as chlorine and bromine. Maintaining the correct pH levels is vital to ensure these biocides can effectively prevent the growth of Legionella bacteria.

Many organisations rely on these tests to confirm proper biocide dosing. Correcting the pH of free-halogen test results is a crucial step in verifying that sufficient biocide is present in the system to inhibit Legionella growth. It’s essential to review your latest test results to ensure they are pH-corrected.

Expert Insights

Dan Sutherland, Senior Trainer for Develop’s Legionella/Water Systems division, emphasised the importance of these updates:

Where the HSE identifies areas of concern and ways in which measures can be improved; notification, understanding, implementation, and management are crucial. Our industry is an evolving one. It goes without saying that control of water chemistry is key for evaporative cooling systems for the control of microbial growth, fouling, scale, and corrosion.

On a personal note, I think all of the industry is pleased that the ball has started to roll on rapid sampling for Legionella – through quantitative polymerase chain reaction (PCR). Keep an eye out for changes afoot for Legionella guidance on hot and cold water systems and other risk systems; these changes will all be incorporated into Develop’s training material so you can rest assured the training you receive from us will always be current and up to date with the latest legislation.”

Staying informed and implementing these updated guidelines is critical for ensuring the safety and efficiency of evaporative cooling systems. By doing so, organisations can better protect against the risks associated with Legionella bacteria.

Accessing the Latest Legionella Guidance

The latest editions of the HSG274 guidance documents can be downloaded for free from the HSE website at:

If you have any questions about legionella and water systems please contact our Customer Service team on 0800 876 6708 or email

Alternatively, you can view our full range of Legionella and Water Systems training on our website here:

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Managing Legionella: A Deep Dive with Senior Water Systems & Legionella Trainer, Dan Sutherland

   1 May 2024         Blogs

Legionella, the bacterium responsible for Legionnaires’ Disease has for many, been a concern for those who manage, install and maintain water systems across various industries, particularly with high risk recirculating systems and healthcare settings. Training is a critical part of competence no matter whether it is an initial or a refresher course and it is critical to develop knowledge and skills continually.

In this in-depth exploration, we turn to Dan Sutherland, a Senior Water Systems & Legionella Trainer at Develop Training, a leading accredited provider of Compliance, Technical, and Safety training.

Understanding the threat of legionella

Legionella pneumophila sero-group 1, the species / strain mostly responsible for confirmed cases of Legionnaires’ disease in the UK, thrives in warm and moist environments, particularly in man-made water systems such as evaporative cooling systems, spa pools, old/complex hot water systems such as those that can be found within hospitals / large commercial buildings.

Dan emphasises the importance of recognising the potential risks associated with Legionella: Pneumonia can not only be fatal (more commonly where there is increased susceptibility) but there is increasing evidence that long term systems will be debilitating for many that recover.

Legislation / Industry Standards

Understanding and adhering to specific industry legislation is crucial for effectively managing Legionella. This is to ensure the safety of persons exposed to the systems. In the UK, there are several statutory / non-statutory legal documents and industry bodies / guides that govern the control and prevention of Legionella-related risks:

  1. Health and Safety at Work Act 1974:

The Health and Safety at Work Act 1974 provides the foundational framework for workplace health and safety in the UK. Under this legislation, employers / anyone responsible for the workplace have a duty to ensure the health, safety, and welfare of their employees and non-employees, including protection against risks associated with Legionella.

  1. Control of Substances Hazardous to Health (COSHH) Regulations 2002:

The COSHH Regulations place specific emphasis on substances and preparations that can pose a hazard to health in the workplace, and Legionella is one such substance. These regulations require employers to assess and control the risks associated with hazardous substances, including the biological parasite Legionella.

  1. Management of Health and Safety at Work Regulations 1999:

These regulations provide a framework for managing health and safety in the workplace. They require employers/persons in control of premises to conduct suitable and sufficient risk assessments, adequately train their staff, plan for incidents, implement control measures, communicate and co-operate and regularly review and update their safety policies.

  1. The Reporting of Injuries, Diseases and Dangerous Occurrences Regulations 2013 (RIDDOR):

RIDDOR requires employers and others, eg someone who has control of work premises, to report to the HSE, accidents and some diseases that arise out of or in connection with work. Legionellosis is a notifiable disease under certain circumstances.

  1. The Notification of Cooling Towers and Evaporative Condensers Regulations 1992 (NCTEC):

These Regulations require employers to notify the local authority, in writing, if they operate a wet cooling tower or evaporative condenser and include details about where they are located. The Regulations also require notification when such devices are no longer in use.

  1. HSE Approved Code of Practice (ACOP) L8: Legionnaires’ Disease: The Control of Legionella Bacteria in Water Systems and associated technical guidance documents

This book is aimed at dutyholders, including employers, those in control of premises and those with health and safety responsibilities for others, to help them comply with their legal duties in relation to legionella. These include identifying and assessing sources of risk, preparing a scheme to prevent or control risk, implementing, managing and monitoring precautions, keeping records of precautions and appointing a manager to be responsible for others.

  1. Legionella Control Association (LCA) Code of Conduct:

The Legionella Control Association (LCA) is a voluntary organisation whose membership comprises providers of services and products concerned with the control of legionella bacteria in water systems. The primary aim is to keep water systems safe and minimise the risk of cases of Legionnaires’ disease caused by poorly maintained systems. The LCA sets out an industry recognised Code of Conduct for legionella service providers and audit their management systems annually.  Adhering to the LCA Code of Conduct demonstrates a commitment to best practices and higher standards in Legionella management.

  1. The Water Management Society

The Water Management Society (WMSoc) is a not-for-profit membership organisation that has been providing practical and technical training solutions to individuals and companies within the water management industry for over 50 years.

The object of the society is to promote the advancement of water management for the benefit of industry, commerce, the environment and the public. In furtherance of this object, but not otherwise:

  • To promote the interchange of scientific information among persons interested in water management by means of meetings, lectures, demonstrations, discussions and publications as appropriate.
  • To encourage education and training in water management.
  • To co-operate with other bodies interested in water management, welfare and technology.

Dan emphasises,

Compliance with these regulations is not just a legal requirement but a fundamental step in ensuring the health and safety of individuals in workplaces. It provides a structured approach to Legionella management, from risk assessment to the implementation of control measures, contributing to a safer environment for everyone.”

In summary, a combination of statutory / non-statutory legislation and industry-specific standards form the regulatory landscape for Legionella management in the UK, providing a comprehensive framework for professionals in water systems management.

Legionella Risk Assessment:

Legionella risk assessment is a fundamental aspect of Legionella management, mandated by legal requirements such as the Control of Substances Hazardous to Health (COSHH) Regulations 2002 and the Management of Health and Safety at Work Regulations 1999.

The risk assessment process should involve a comprehensive evaluation of water systems and the way they are managed, identifying potential breeding grounds, susceptibility to infection and the culture of management. It should provide a structured understanding of the system, leading to the formulation of targeted control measures including temperature/chemical management, regular and appropriate maintenance and ensuring competency of those that work on systems. The report generated serves as a record of compliance and due diligence.

A proactive and ongoing process, Legionella risk assessment ensures the prevention of Legionnaires’ disease by regularly reviewing and updating control measures in response to evolving water system conditions.

Dan stresses the need for a systematic approach:

The law requires suitable and sufficient risk assessment. The assessor’s competence / their employer’s management systems / how well the risk assessment was prepared for before the day are each critical components. It should involve an assessment of records, a survey of the system and attempts made to verify the necessary competency is in place. Risk assessment is the first step for many and so poor risk assessment will lead to poor understanding and control going forward for some.  Conducting a thorough risk assessment is not only a legal requirement but also a proactive measure to identify potential hazards.”

Training for Legionella Management:

Ensuring employees are suitably qualified in the management of Legionella / implementation of controls, helps to safeguard public health as well as ensure compliance with stringent regulations. Specialised training is essential for effective Legionella management.

Dan explains,

Develop Training offer a range of Legionella / Water System courses from Awareness to Role of the Responsible Person, Risk Assessment and Water Regulations/Byelaws amongst others. Our aim is to empower learners with the knowledge and understanding they need for their role, to take the proactive measures needed to control Legionella”.

With so much to know and understand in this sector (where we touch on aspects including plumbing, legal requirements, water systems, water treatment and risk assessments etc)., Legionella training goes beyond theoretical knowledge. It equips learners with practical skills to manage risks / implement controls effectively. We all take new knowledge away from training no matter how experienced you are.

The full list of Water Systems & Legionella courses offered by Develop can be found here:

Ongoing Legionella Monitoring and Control Measures:

Effective management of Legionella doesn’t end with a one-time risk assessment. Regular water testing, temperature checks, and maintenance of water systems are essential for preventing Legionella growth. Professionals must implement control measures and, importantly, revisit and update these measures regularly.

Information from Industry Bodies:

Industry Bodies such as the HSE, LCA and WMSoc are integral to organisations who want to stay updated on the latest developments in Legionella management and grow their knowledge base. Professionals are able to access valuable resources, stay informed about emerging trends and network with peers facing similar challenges.

The Future of Legionella Management:

As technology evolves, so do the tools available for Legionella management. Dan envisions a future where smart monitoring systems play a crucial role:

Automation and real-time monitoring could revolutionise Legionella management in the future and it is already is for some. Real time results, analysis and notification can only be a beneficial tool to aid control. Imagine a system that detects temperature variations or water quality issues instantly, allowing for swift intervention and prevention.”


Managing Legionella is a complex and ongoing process that demands the expertise of trained professionals. Through specialised training, compliance with regulations, and a proactive approach to risk assessment and controls, individuals working in water systems can contribute to a safer environment.

As technology continues to advance, the future of Legionella management holds promising innovations, ensuring the ongoing battle against this persistent bacterium remains at the forefront of water system safety.


Contact us

If you have any questions, or require more information about the training offered by Develop, please contact our Customer Service team on 0800 876 6708 or email

The full list of Water Systems & Legionella courses offered by Develop can be found here:

About the Author

Dan Sutherland, Senior Water Systems & Legionella Trainer

Dan has experience of working at various water hygiene and treatment companies and training for over 17 years. In risk assessment, his experience led him to work in progressingly more complex and high risk environments involving commercial hot and cold water systems, spa pools systems, vehicle wash systems and other manufacturing systems. Notably, Dan completed the legionella risk assessment of the Wimbledon Tennis Championships complex and Gleneagles golf resort.

Plumber fixing an apartment shower

Managing Legionella – how much do you know?

   01 April 2024         Blogs

Waterborne diseases pose a significant threat to public health, and among them, Legionnaires’ Disease is a serious and potentially fatal illness. Legionella, the bacteria responsible for causing a potentially severe form of respiratory infection can thrive in various water systems. Therefore, all organisations need to be sure that they meet the relevant HSE guidelines to effectively manage the risks.

Legionella bacteria are found in warm water environments such as cooling towers, hot tubs, and plumbing systems and will multiply when temperatures are between 25° and 45°C. When contaminated water droplets are inhaled, individuals can contract Legionnaires’ disease, leading to pneumonia-like symptoms. To effectively manage Legionella, it’s crucial to first understand its habits and potential breeding grounds.

If you are an employer, self-employed or someone in control of premises, it is important that you understand and mitigate the risks associated with Legionella. You are principally responsible for the health and safety of anyone affected (unless otherwise agreed through a contractual arrangement for legionella) and should take the necessary precautions to reduce the chances of exposure to the disease.

Here are some ways that you can do that:

Identify Environments At-Risk of Legionella

Legionella thrives in stagnant or warm water, making cooling towers, spa pools and hot water systems common breeding grounds. Additionally, places like hospitals and long-term care facilities, where individuals may have compromised immune systems, are at higher risk. Identifying and regularly monitoring these environments is crucial in preventing Legionella outbreaks.

Temperature Control

The primary method used to manage Legionella is to operate water services at temperatures inhospitable for the bacteria. Hot water cylinders should therefore store water at 60°C minimum, and distribute at no less than 50°C within one minute. Cold water should be stored at less than 20°C and distributed at less than 20°C within two minutes.

However, a recent update to Part L of Building Regulations (Conservation & Power) now emphasises that for newly installed or refurbed heating systems, heating system flow temperatures should not exceed 55°C, and ideally, they should be kept below this threshold.

While this change brings about several advantages in terms of energy efficiency and environmental impact, it also introduces a new consideration for those that manage secondary hot water systems heated by them — the increased risk of Legionella bacteria formation in hot water systems due to decreased hot water flow, return and distribution temperatures.

You can find out more about these changes here.

Routine Checks

A routine inspection and clean is an obvious, but important part of preventing Legionella. If necessary, periodic water samples should be analysed. How often depends on the system and the outcome of any risk assessment. Further guidance can be found here on the HSE’s website.

Flush the Pipes

Legionella can multiply in hot and cold water systems. Stagnant water attracts Legionella growth, so ensuring all dead ends are removed and all outlets are flushed out at least weekly, will help to reduce the risk.

System Design

When designing hot and cold water systems, pre-empt the risks of Legionella by keeping pipe-work as short as possible, include adequate insulation and minimise heat gain/thermal transfer from pipes. Contamination should also be prevented i.e. tanks to be fit with lids, insect screens where pipes are open to the environment and control the risks of backflow
For a more in-depth overview, please visit the HSE website:

In conclusion

As a business, the best way to ensure you are fulfilling your duties and managing the risk effectively is to ensure people responsible for managing systems and implementing controls are appropriately trained and receive regular refresher training.

Develop Training offer a number of Legionella courses including,

Legionella & ACOP L8 Awareness

Legionella: Role of the Responsible Person / Duty Holder / Landlord

Management of Legionella Bacteria in Hot & Cold Water Systems

Legionella Risk Assessment of Hot & Cold Water Systems

To view the full list of available Water Systems & Legionella training offered by Develop, click here:


Contact us

If you have any questions or are unsure which training course is right for you, please contact our Customer Service team on 0800 876 6708 or email

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Why legionella awareness is key to tackling outbreaks

   01 March 2024         Blogs

Legionella continues to dominate the news and every year hundreds of cases of Legionnaires’ Disease are reported in the UK alone. The World Health Organization reports that “the death rate may be as high as 40–80% in untreated immuno-suppressed patients [but] can be reduced to 5–30% through appropriate case management and depending on the severity of the clinical signs and symptoms. Overall the death rate is usually within the range of 5–10%.”

A recent outbreak at a plastics manufacturing company in West Bromwich resulted in five members of the public becoming infected with Legionnaire’s Disease after Legionella bacteria grew in their water cooling towers and pipes. One of the five people infected was taken to intensive care and put on a ventilator after being infected – highlighting just how serious the disease can be. The company were subsequently investigated by the HSE and fined £50,000 and ordered to pay £11,000 in costs. Further information on the news story can be found here.

What is the fine for legionella in the UK?

Due to outbreaks such as these, The Health & Safety Executive (HSE) is extremely active, and regularly goes ahead with criminal prosecutions against those failing to adhere to the law. Sanctions and prosecutions vary but will occur if the law isn’t adhered to, and in extreme cases can even result in imprisonment.

One of the largest fines of £1.8m was given to G4S Cash Solutions (UK) after they failed to maintain their water systems in compliance with the Health and Safety at Work Act, Management of Health and Safety at Work Regulations 1999, Control of Substances Hazardous to Health Regulations 2002, and ACOP L8, the Health and Safety Executive’s approved code on the control of Legionella in water systems.

What are the symptoms of Legionnaire’s Disease?

The early symptoms of Legionnaires’ disease are similar to those of the common flu and include muscle aches, tiredness, headaches, dry cough and fever. Some make a full recovery but there is increasing evidence that long term symptoms for many will include breathlessness, fatigue and impact on the neurological and neuromuscular system.

Does my business need to be concerned about legionella?

Legionella can be found in any premises/water system. Along with potentially fatal consequences, a Legionella outbreak can have serious legal and financial implications for an organisation/individual. It is recommended that anyone responsible for a facility or maintaining a water system has an awareness of legionella at the very least.

Some industries/water systems may be more at risk, such as:

  • Healthcare settings i.e. Hospitals, nursing and care homes
  • Evaporative cooling systems
  • Spa pool systems
  • Older, larger and complex hot and cold water systems
  • Industrial and manufacturing water systems

Building and business owners and managers are responsible for their work premises under;

  • Health and Safety at Work Act 1974 (sections 2, 3, 4)
  • Control of Substances Hazardous to Health (COSHH) Regulations 2002 (Regulations 6,7,8,9 &12)
  • Management of Health and Safety at Work Regulations 1999

It is their principal legal responsibility to uphold a duty of care, ensuring the safety of your business, properties, and water systems by guarding against potential legionella growth and disseminating/inhalation of water aerosols.

The Health and Safety Executive’s Approved Code of Practice (ACoP) L8 serves as a crucial guideline for preventing and controlling legionellosis in water systems. This document holds a unique legal status, making employers susceptible to prosecution, fines, or even imprisonment if it is demonstrated that the relevant provisions of the Code were not adhered to.

Legionella Awareness training in-line with ACoP L8

Develop Training provides a range of Legionella awareness and more advanced training courses to reduce the risks associated with Legionella bacteria and support compliance with the L8 Approved Code of Practice (ACoP).

Our Legionella and ACoP L8 Awareness course covers a background on legionella and the risks it offers, introduces water systems, legal requirements and controls including risk assessment, management pathways, ACOP L8/HSG274 and monitoring / maintenance duties for hot and cold water systems.

An awareness of Legionella (as a minimum) is needed for those who implement and monitor precautions such as little used outlet flushing and temperature monitoring. The more informed your workforce is on the dangers associated with legionella bacteria and the conditions under which they thrive, the more competent individuals will be in taking preventative action and recognising warning signs.

To view the full list of available Water Systems & Legionella training offered by Develop, click here:

Contact us

If you have any questions or are unsure which training course is right for you, please contact our Customer Service team on 0800 876 6708 or email


10 things to know about Legionnaire’s Disease

   12 February 2024         Blogs

As an employer, a self-employed person, or person in control of a premises (in connection with water systems), prioritising the health and safety of your employees, non-employees and tenants is of paramount importance. One potential threat that demands your attention is Legionnaire’s Disease. Understanding and mitigating the risks associated with this bacterial infection is crucial to ensuring a safe environment for everyone.

1. A brief history of Legionnaire’s Disease

Legionnaire’s Disease, named after an outbreak in Philadelphia in 1976 that affected members of the American Legion, is a relatively recent discovery. The bacteria responsible for the disease, Legionella, was transmitted through an air conditioning unit, resulting in 221 reported cases and the death of 34 people.

2. Where can legionella bacteria be found?

Legionella bacteria naturally exists in water and moist soil, with warm and stagnant water providing an ideal breeding ground. Identifying and addressing these conditions is essential to minimising the risks associated with Legionnaire’s Disease.

3. Legionnaire’s Disease:

Legionnaires’ Disease, caused by Legionella bacteria, can be fatal in 5-10% of cases, especially if not diagnosed early. In 2020 (January to October) the UK saw 295 cases (but this number was around 500 cases for the two proceeding years) making awareness and preventative measures crucial.

4. Effects and symptoms of Legionnaire’s Disease

The disease is characterised as acute bacterial pneumonia, with symptoms such as coughing, shortness of breath, fever, and aches. Diagnosing Legionnaire’s Disease can be challenging due to its similarity to other forms of pneumonia.

5. How is it contracted?

Inhalation of water droplets in the air (an aerosol) contaminated with Legionella bacteria is the primary mode of transmission. Certain individuals, including those over 50, smokers, and those with respiratory diseases, are at a higher risk.

6. Transmission:

While the disease cannot be transmitted between people, cases generally peak in the summer and autumn months, due to the increased temperatures at those times of year.

7. Legionnaire’s outbreaks:

Though fairly uncommon, outbreaks in large buildings or estates with complex water systems, such as hotels and hospitals, can be dangerous. In mid-2023 two Scottish hospitals were reported to have traces of Legionella bacteria during routine checks in the radiotherapy unit and water supply. These cases highlight the importance of regular Legionella testing, especially in places such as hospitals and care homes where people may be more susceptible to infection and serious illness.

Outbreaks in large buildings are also particularly dangerous because the symptoms are often delayed and commonly misdiagnosed, which can lead to a larger number of fatalities.

8. Treatment of Legionnaire’s:

Early diagnosis allows for prompt treatment with antibiotics, resulting in successful recovery for most individuals. However, some may experience long-term effects such as breathlessness and fatigue.

9. Why should businesses be careful?

Any water system has the potential to harbour the bacteria. Cooling towers, spa pools and showers are most commonly linked to outbreaks, because of the high volumes of breathable droplets they produce. Higher risk systems commonly include:

  • Evaporative cooling systems
  • Spa pools
  • Large, older and complex hot and cold water systems
  • Recirculating vehicle wash systems
  • Manufacturing water systems such as wet paint spray booths

Some outbreaks have even been attributed to public fountains, air conditioning systems and even the misters found in supermarkets.

Mitigating the risk of a possible outbreak of Legionnaire’s is your responsibility as a business owner/person with high level authority/manager. Vigilance is required to prevent dangerous outbreaks, otherwise the penalty for not doing so can stretch from fines to imprisonment.

An employer’s duties to control legionella in the workplace are set out in:

  • The Health and Safety at Work Act 1974 (HSWA)
  • The Management of Health and Safety at Work Regulations (MHSWR)
  • The Control of Substances Hazardous to Health Regulations 2002 (COSHH)
  • Reporting of Injuries, Diseases and Dangerous Occurrences Regulations 2013 (RIDDOR)
  • The Notification of Cooling Towers and Evaporative Condenser and Evaporative Condenser Regulations 1992 (NCTEC)

According to the duties listed under the HSWA, the key obligations of an employer to reduce the risk of exposure to Legionella on their premises include having to:

  • Monitor their water temperature at regular intervals
  • Flush little used outlets to remove biofilm from the system
  • Record results of Legionella testing and retain them for at least five years

10. Prevention:

Businesses must take proactive steps to prevent Legionnaire’s Disease, including regular water system maintenance, temperature control, chemical treatment, and minimising the escape of water droplets. Employing contractors for water treatment and ensuring staff are well-trained are essential components of an effective prevention strategy.

Whilst all involved in working on and managing water systems have responsibilities (and this includes contractors and sub-contractors), the principal responsibility is the Duty Holder’s. More information on responsibilities is available through the HSE.

Ultimately, the best way to ensure your business is fulfilling its duties and managing the risk effectively is to start the journey (or refresh your knowledge) with training/refresher training.

Develop Training offer a number of Legionella courses including,

To view the full list of available Water Systems & Legionella training offered by Develop, click here:

Legionnaire’s Disease poses a real threat, but with awareness, responsible management, and proactive prevention measures, you can create a safer environment for your tenants, employees, non-employees and customers. Stay informed, take action, and prioritise the well-being of those under your care.

Contact us

If you have any questions or are unsure which training course is right for you, please contact our Customer Service team on 0800 876 6708 or email

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