Commercial Legionella Risk Assessments: ACOP L8 Compliance Guide

Commercial legionella risk assessments are a legal requirement for all premises with a water system that could create a risk of legionella exposure. The Approved Code of Practice L8 (ACOP L8) and its associated technical guidance (HSG274 Parts 1, 2, and 3) set out the framework for identifying, assessing, and controlling legionella risks in commercial water systems.

Under ACOP L8, employers and those in control of premises must identify and assess sources of legionella risk, prepare a written scheme for preventing or controlling the risk, implement, manage, and monitor precautions, keep records, and appoint a competent responsible person. The risk assessment must be carried out by a competent person and reviewed at least every two years or when there’s reason to believe it may no longer be valid.

Commercial water systems present specific legionella risks that may not apply in residential settings. These include cooling towers and evaporative condensers, hot and cold water systems serving large buildings, spa pools and whirlpool baths, humidifiers and air washers, and water features. Each system type has specific control measures detailed in HSG274.

Key control measures for commercial legionella risk management include maintaining hot water temperatures above 60°C at the calorifier and above 50°C at outlets, keeping cold water below 20°C, regular flushing of low-use outlets, cleaning and disinfection of water storage tanks, monitoring and treatment programmes for cooling towers, and maintaining detailed records of all monitoring and maintenance activities.

Temperature monitoring is a critical ongoing control. Monthly temperature checks at sentinel outlets (the nearest and furthest from the heat source) should verify that hot water reaches at least 50°C within one minute of running. Cold water should be below 20°C within two minutes. Any deviations require investigation and corrective action.

Custodia’s legionella compliance module supports commercial legionella risk assessment tracking, temperature monitoring records, flushing regime management, and integration with water treatment contractors to provide a complete legionella risk management solution.