Legionella risk assessment and control checklist

Responsibility and assessment

• A responsible person is appointed in writing with the authority and training to manage Legionella risk, with a deputy for absence (SANS 893-1).
• Legionella is addressed in the hazardous biological agent risk assessment required under the Hazardous Biological Agents Regulations, 2022, made under the Occupational Health and Safety Act.
• A written Legionella risk assessment covers every water system that can create aerosols or hold water between 20 °C and 45 °C: hot and cold water services, showers, cooling towers and evaporative condensers, spa pools, humidifiers, misting systems, vehicle washes, fire sprinklers and dead legs.
• The assessment is reviewed at least every two years (SANS 893-1; Hazardous Biological Agents Regulations regulation 6(6)), after a change to the system or its use, after a positive result, and after a case of Legionnaires' disease linked to the site.
• A schematic of each water system is current, showing tanks, calorifiers, outlets, little-used outlets, dead legs, thermostatic mixing valves and the points where temperature is monitored.

Controls

• Cold water is stored and distributed below 20 °C, and hot water is stored at 60 °C or above and reaches outlets at 50 °C or above within a minute of running.
• Temperatures are checked and recorded at the frequency the control scheme sets.
• Little-used outlets are flushed weekly, or removed, and the flushing is recorded.
• Storage tanks are inspected, lidded, insulated and cleaned on a schedule, and sediment and biofilm are not present.
• Showers and spray outlets are dismantled, cleaned and descaled on a schedule.
• Cooling towers and evaporative condensers have a written control scheme: water treatment with a biocide programme, drift eliminators, cleaning and disinfection at least twice a year, and monitoring of the treatment chemistry.
• Thermostatic mixing valves are positioned as close as possible to the outlet and are serviced.
• New systems or long-shutdown systems are flushed, disinfected and sampled before they return to use.

Monitoring and records

• Legionella sampling is done where the risk assessment requires it, by a laboratory accredited for the method, and the action levels and responses are written down before results arrive.
• A positive result triggers the written response: investigation, disinfection, resampling and, where a case is linked to the site, cooperation with the Department of Health (Legionellosis is a Category 2 notifiable medical condition) and reporting of an occupational disease under the OHS Act.
• Records are kept as the Hazardous Biological Agents Regulations require (the risk assessment for 40 years, inspection and test records for five years, training records for as long as the employee is employed) and are available to an inspector.
• Staff whose work exposes them to aerosols (maintenance, housekeeping, cooling tower work) have Legionella awareness training, and the responsible person has completed the responsible person course.