Overview of HSG274 Part 2: Legionella bacteria in hot & cold water systems

hsg274-part2Important changes to the way the UK’s Health & Safety Executive deal with the control of legionella bacteria and Legionnaires' disease in HOT & COLD WATER SYSTEMS have now been published... find out how they affect you with our detailed review and forthcoming breakfast briefings.

The formal system of legionella control in the UK now comprises the HSE's ACOP L8 (4th edition) and HSG274 which is split into three parts:

  • Part 1 - cooling water systems.
  • Part 2 - hot and cold water systems – recently published April 2014.
  • Part 3 - other risk systems.

Are Hot & Cold Water Systems Important?

Hot and cold water systems, covered by the recently published HSG274 Part 2, are by far the most common form of water system that can potentially create a legionella risk and so these changes are likely to affect you, your staff and your organisation. It is therefore very important that you understand the changes and adjust your legionella risk management systems to remain fully compliant with the law.

10 Key Points – What You Need to Know & More...

Our legionella experts have now conducted a detailed review of the new HSG274 Part 2 (Hot & Cold Water) and we have summarised 10 key points:

1. HSG274 Part 2, the guidance covering hot and cold water systems has now increased significantly from 15 to 58 pages... a big increase by any standards. Our teams are now advising clients on what they need to do to remain compliant, and expediting the implementation of any changes required.

2. All risk assessments should now consider both the relative risks associated with legionella bacteria and scalding from hot water. A good understanding of the process of thermal disinfection is now also essential to complete a competent risk assessment.

3. There is now significantly more information covering water system engineering design, including:

  • Calorifiers attached to solar heating systems.
  • Expansion vessels.
  • Point of use water heaters and combination water heaters.
  • Clarification on what is a “sentinel” outlet on large multi-loop systems.
  • There is also a simple definition of a low risk system.

4. New Section: “Residential accommodation: Landlords and shared premises”. This new section gives guidance on how to risk assess and control both domestic and commercial tenanted properties. It is essential that property owners, landlords and tenants understand this new section.

5. New Section: “Special considerations for healthcare and care homes”. The guidance gives new information on those special considerations where there are susceptible individuals, including revised guidance on acceptable levels of legionella bacteria in water systems. Our experts are already advising senior health and safety teams and facilities operators in the healthcare sector on the new rules to help them to maintain their compliance status.

5. Commissioning of new buildings has in the past resulted in significant legionella growth. There is now a significant section devoted to this topic which includes guidance when “mothballing” water systems for times of non-use. This is an important area for builders, developers and other owners of property and one that needs careful consideration.

7. Potential problems are highlighted for hot water systems with secondary and tertiary loops; systems that are prevalent in hospitals and healthcare facilities. The guidance also introduces new recommended requirements for routine monitoring.

8. New routine monitoring recommendations are now included, including point of use heaters, combination heaters, TMV’s and others. Additional routine monitoring tasks and KPI's will be required as a result.

9. Significantly increased section on the use and control of chemical water treatments and biocide systems. Our teams are able to advise in detail on this increased guidance.

10. Appendices included in the new guidance define much broader requirements for the risk assessment and written control scheme including the need for incident planning. Several of our legionella experts are incident planning specialists and advise on the development, implementation and management of such plans.

These issues and more will be covered in greater detail at our breakfast briefings.

Additionally, if you are interested in some further reading a copy of the full HSG274 Part 2 is available to download at the bottom of this page.

Breakfast Briefings – Get Up To Speed Quickly

To help duty holders, health and safety managers, business owners and those responsible for the management of risk systems understand these changes and ensure their legionella risk management systems and procedures remain compliant with the law we will be presenting a second series of concise breakfast briefings at a number of central locations... breakfast briefings.

More on our breakfast briefings

More Information

More information can be obtained from my colleagues Jamie Tranter or Ian Griffiths at Legionella Control International on 0161 877 0586 or email This email address is being protected from spambots. You need JavaScript enabled to view it..

Free Downloads

To download your complimentary copy (full version) of the HSE’s new HSG274 Part 2 please use the following web link:

Other downloads

If you are unable to download the documents here please feel free to call us on 0161 877 0586 or email This email address is being protected from spambots. You need JavaScript enabled to view it..


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Manchester: +44 (0) 161 877 05 86
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Email: info@legionellacontrol.com

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