Temperature monitoring under HSE ACOP L8 tells you whether conditions for Legionella growth are being controlled. Microbiological water sampling taking actual water samples and testing them for Legionella bacteria is a separate, additional layer of assurance. It is required in high-risk premises and following certain trigger events.
Why this matters
A care home where temperatures are being monitored but where Legionella has colonised the system can generate positive sample results even with apparently compliant temperatures. Sampling is the only way to confirm the absence of colonisation. A Legionella outbreak in a care home is a notifiable incident with serious consequences for residents and the provider.
What to do
- 1Review your L8 written scheme to confirm whether microbiological sampling is specified if not, discuss with your L8 consultant whether it should be.
- 2For high-risk sites (immunocompromised residents, complex water systems, recent L8 failures), quarterly sampling at sentinel outlets is standard practice.
- 3Sampling must be carried out by an accredited laboratory using the correct method (ISO 11731 for Legionella).
- 4Following any positive Legionella result, a documented emergency response procedure must be enacted immediately do not wait for confirmation or repeat testing before acting.
- 5Retain all sample results and laboratory certificates with your L8 monitoring records.
Primary source
HSE HSG274 Part 2 The control of Legionella bacteria in hot and cold water systems
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