HSG274 Part 2 was revised in 2024 - what it means for your written scheme

HSG274 Part 2 is the HSE's technical guidance for the control of Legionella in hot and cold water systems. It sits underneath ACoP L8 and is the document most written schemes of control are built on. The HSE issued a revised edition in 2024, and we are still meeting sites whose control scheme quotes the old text.

What actually changed

The revision did not rewrite the approach. Temperatures, flushing, inspection frequencies and the responsibilities of the duty holder and responsible person are all recognisable from the previous edition. What the HSE did was clarify areas where sites were interpreting the guidance loosely:

• Little-used outlets. The wording around identifying and flushing infrequently used outlets is firmer, and the expectation that flushing is recorded, not just done, is clearer.
• Thermostatic mixing valves. The guidance on where TMVs are justified, and on servicing and fail-safe testing, is more explicit.
• Monitoring and records. The revision leans harder on records being reviewed, with out-of-range results triggering a documented corrective action rather than simply being filed.
• Competence. The expectation that people carrying out monitoring tasks are trained and their competence is recorded is spelled out more plainly.

Do you need a new risk assessment?

Usually not on the strength of the revision alone. ACoP L8 requires the risk assessment to be reviewed regularly and whenever there is reason to suspect it is no longer valid. A change in guidance is a reasonable prompt to review, but if your systems, usage and control measures have not changed, a documented review noting that the assessment remains valid is normally sufficient.

What you probably do need

The written scheme of control is where the revision bites. If your scheme references specific paragraphs, tables or wording from the previous edition, it should be updated so the people following it are working to current guidance. In practice that means:

1. Checking every reference to HSG274 Part 2 in the scheme and the monitoring records.
2. Confirming the flushing regime covers all little-used outlets and that the records show who flushed what and when.
3. Making sure TMV servicing and fail-safe testing are scheduled and evidenced.
4. Confirming the training records for the staff doing the monitoring are current.

Republic of Ireland sites

HSG274 is UK guidance. In the Republic of Ireland the reference document remains the HPSC National Guidelines for the Control of Legionellosis in Ireland (2009), alongside the Health and Safety Authority's requirements. Cross-border operators often adopt HSG274 as a practical standard on Irish sites as well, which is sensible, but the written scheme should say so explicitly and name the Irish guidance it is also meeting.

If you would like a second pair of eyes on a written scheme, we review schemes independently and tell you plainly what needs to change and what does not.