Guide
ACOP L8 explained: the legionella code of practice in plain terms
Updated
L8 is the document every legionella quote leans on, so it is worth knowing what it is: not a statute, but a code with special legal status that defines what competent compliance looks like.
What an approved code of practice is
ACOP L8, Legionnaires' disease: the control of legionella bacteria in water systems (fourth edition, 2013), is approved by the Health and Safety Executive. An ACOP has special status: following it is proof of compliance with the underlying law on the points it covers, and if you depart from it, a court can find you in breach unless you show you complied in some other equally effective way (HSE legionella pages). The underlying duties come from the Health and Safety at Work etc. Act 1974 and COSHH 2002.
Who L8 applies to
- Employers and those in control of premises, including landlords of residential accommodation.
- It applies where water is stored or used in a way that can expose people to droplets, hot and cold water systems, cooling towers, evaporative condensers, spa pools and similar.
- Cooling towers and evaporative condensers carry an additional duty: notification to the local authority under the Notification of Cooling Towers and Evaporative Condensers Regulations 1992.
What L8 requires
- Risk assessment
- Identify and assess sources of risk. This is the foundation duty and the product this site prices: typically £60–£150 for simple premises, £200–£600+ for complex ones (typical 2026 quotes).
- Responsible person
- Appoint someone competent to take day-to-day responsibility for controlling any identified risk.
- Written scheme of control
- Where risk is identified, prepare and implement a written scheme for preventing or controlling it: temperature regimes, flushing, cleaning and disinfection, monitoring.
- Records and review
- Keep records of the assessment, the scheme and the monitoring, and review the assessment when circumstances change.
The technical detail lives in HSG274
L8 sets the legal framework; the operational detail sits in HSE's technical guidance HSG274, published in three parts: evaporative cooling systems, hot and cold water systems, and other risk systems. The temperature regime most assessments check against, hot water stored at 60°C and distributed at 50°C or above, cold water below 20°C, comes from HSG274 Part 2; verify the exact figures for your system type against the current guidance before writing them into a control scheme.
If a quote cites L8 at you as a reason to buy extras, ask which paragraph. The code requires assessment, competence, a control scheme where risk exists, and records, it does not mandate annual testing of simple domestic systems or any certificate. See testing vs risk assessment.