Legionella temperature checks under L8 and HSG274, logged continuously
In Great Britain, the HSE Approved Code of Practice L8 and its guidance HSG274 set how dutyholders control Legionella in water systems. Most of the routine evidence is temperature and use at outlets. Aqueduct logs both continuously, so a missed check or a cold calorifier shows up the same day.
Who it applies to
Employers and anyone in control of premises, including landlords, under the Health and Safety at Work Act and the COSHH Regulations. L8 is in its fourth edition (2013). HSG274 comes in three parts: evaporative cooling systems, hot and cold water systems, and other risk systems.
The dutyholder must assess the risk, appoint a responsible person, put a written scheme in place and keep records. With fewer than five employees the assessment need not be written down, though the duty remains. Cooling towers must be notified to the local authority.
Routine checks for hot and cold water systems
Limits and frequencies from HSG274 Part 2. Your responsible person and competent advisers own the written scheme.
| Requirement | What it asks for | Data Aqueduct supplies |
|---|---|---|
| Calorifiers, monthly | Flow as close to 60°C as practicable and not below; return not below 50°C. | Flow and return temperature probes logged every few minutes. |
| Hot water sentinels, monthly | At least 50°C within one minute, 55°C in healthcare premises. | Outlet or pipe temperature at sentinel points, with time to temperature. |
| Cold water sentinels, monthly | Below 20°C within two minutes of running. | Cold supply temperatures at sentinel points and tanks. |
| Little-used outlets, weekly | Outlets unused for seven days or more flushed, or as the risk assessment says. | Flow or temperature change at the outlet, showing whether it was actually used. |
| Records, L8 paras 70 to 72 | Dated records of each check; monitoring records kept at least five years. | Every reading stored with its time and location, exportable by period. |
Numbers that matter
The temperature range in which Legionella grows, which the risk assessment must consider.
Source: HSE L8, fourth editionMinimum retention for monitoring records.
Source: HSE L8, fourth editionSecond edition of HSG274, updating Part 1 on evaporative cooling systems.
Source: HSE HSG274Related standards
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Related
Common questions
They can supply the readings, and many dutyholders use them that way. Whether they replace manual checks is a decision for the risk assessment and written scheme, which the responsible person signs off.
It is accepted evidence, but it cannot show duration or catch outlets that were skipped. A sensor record of each run is harder to dispute in an investigation.
Healthcare premises use a 55°C hot water sentinel limit rather than 50°C, and in England and Wales follow HTM 04-01 alongside HSG274. Aqueduct holds the healthcare limit for those outlets and flags any sentinel slow to reach it. See hospitals.
Yes, where outlets or their branches carry flow or temperature sensors. Each flush leaves a signature in the readings, so Aqueduct lists outlets idle for seven days or more and confirms which ones were run. The written scheme still sets which outlets need flushing.
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