HSG274 2024: What Changed and What You Need to Do

The Health and Safety Executive published the updated edition of HSG274 in 2024, marking the most significant revision to the UK's legionella technical guidance in a decade. If you carry out legionella risk assessments, this update directly affects your work.

Here is a practical summary of what changed and what you need to do about it.

The headline changes

The 2024 edition is not a wholesale rewrite -- the fundamentals of legionella control remain the same. But there are several areas where the guidance has been expanded, clarified, or tightened.

Scalding risk is now part of the assessment

This is arguably the biggest shift. The 2024 edition explicitly links legionella risk and scalding risk, requiring assessors to consider both within a single assessment. Previously, many assessors treated scalding as a separate matter (or did not address it at all).

What this means in practice: you now need to assess TMV locations, check that they are appropriate for the population using them, consider the legionella risk in downstream pipework, and recommend a TMV maintenance programme.

Solar thermal and heat pump guidance

For the first time, HSG274 includes meaningful guidance on solar thermal heating systems and air-source heat pumps. These systems can produce variable water temperatures that may fall within the legionella danger zone. The new guidance requires assessors to check that stored water consistently reaches 60 degrees C, regardless of the heat source.

Incident planning is now expected

The 2024 edition makes incident planning an explicit expectation rather than a suggestion. Assessors should check whether the duty holder has a documented response plan for suspected legionella cases, including notification procedures, system shutdown protocols, and access to specialist cleaning services.

Record-keeping is more prescriptive

The new edition specifies a five-year minimum retention period for monitoring records and makes electronic records explicitly acceptable. It also emphasises that records should show not just what was monitored but what was done with the results -- evidence that someone reviewed the data and took action where needed.

Little-used outlets and building closures

The experience of COVID-19 building closures clearly influenced the 2024 edition. There is now more detailed guidance on:

• Defining "infrequently used" outlets (any outlet not used at least weekly)
• Managing buildings during periods of closure
• Recommissioning procedures when buildings return to use
• Re-assessing risk after significant changes in occupancy patterns

What you need to do

If you are an experienced assessor, the 2024 changes have practical implications:

Update your assessment template. If you use a paper-based or spreadsheet template, you need to add the new conditions: scalding risk, solar thermal systems, incident planning, and enhanced record-keeping checks.

Brief your clients. Many duty holders will not be aware of the changes. A brief summary of the key updates -- particularly around scalding risk and incident planning -- demonstrates your value and helps your clients stay ahead of enforcement.

Review your standard recommendations. Some of your standard recommendations may need updating to reference the 2024 edition rather than the superseded 2014 version. Check that your recommended monitoring frequencies align with the updated Table 2.1.

Check your own CPD. If your last training was before the 2024 publication, consider refresher training that covers the new requirements.

What has not changed

It is worth noting what remains the same:

• The fundamental temperature requirements (cold below 20 degrees C, stored hot at 60 degrees C, distributed hot at 50 degrees C)
• The requirement for competent person assessment under ACOP L8
• The duty holder's overall responsibility for managing legionella risk
• The need for a written scheme of control
• The basic structure of Table 2.1 monitoring frequencies

The 2024 edition builds on the existing framework rather than replacing it. If your assessments were already thorough and well-structured, the changes are manageable. If they were not, the new edition raises the bar.

L8Pro includes all 67 risk conditions from the 2024 edition, including the new requirements for scalding risk, solar thermal systems, and incident planning. Every assessment you complete with L8Pro is automatically aligned with the current guidance.