Legionnaires disease investigation by local government

Local government authorised officers have a legislated role with powers to investigate cooling tower systems and enforce compliance with the Health (Air-handling and water systems) 1994.

Local government authorised officers play a crucial role in investigating outbreaks of Legionnaires’ Disease.

A Legionnaires’ Disease investigation should be viewed as an immediate priority by a local government. 

Multiple authorised officers may be required to support the investigation of a Legionnaires’ Disease outbreak, depending on the number of cases.

It is often very difficult to pinpoint the source of a Legionnaires’ Disease outbreak with accuracy. The main aim of a public health response is to stop the outbreak by ensuring that cooling towers and other possible sources of infection suspected to be the cause of the outbreak are controlled as quickly as possible. 

Role of local government authorised officers

Authorised officers support Legionnaires Disease outbreak investigation by carrying out environmental investigations, using their powers to investigate cooling towers and water systems, and enforcing compliance with the Regulation.

The environmental investigation aims to locate possible sources of aerosols containing Legionella bacteria (such as cooling towers) in the area where the Legionnaires Disease cases were potentially exposed.

Refer to the Investigating Legionnaires Disease guideline for local government (PDF 100KB) for further information. 

The steps of environmental health investigations may involve:

  • working with the Department of Health and Population Health Unit, to assist with mapping the investigation areas based on reviewing the movements of the cases and defining an area of common outdoor or indoor exposure between these cases
  • where a register of cooling towers and other regulated systems has been maintained by the local district, review system locations within the investigation area(s):
    • undertake physical inspections of building cooling towers as well as unregulated sources within a local district, such as water fountains, misting systems and ice machines within defined areas to identify and sample possible sources of L. pneumophila. Obtain samples and review maintenance records where available. Collect evidence as required.
    • undertake a physical inspection of other regulated systems, such as water systems where exposures occur inside buildings, and there is indication that a single building had been visited by more than one case. Obtain samples and review maintenance records where available. Collect evidence as required.
    • where a system is visibly unclean with sediment or algae, or maintenance records are unavailable or out of date, advise owner to immediately clean and disinfect their systems
    • as the laboratory results became available, advise owners of cooling towers whose systems tested positive to shut down and/or decontaminate systems
  • where a register is not available, work with WA water treatment companies who undertake the regular maintenance and testing of cooling towers within the investigation area and ask to:
    • contact their client list advising of outbreak within the area
    • advise clients to undertake emergency decontamination of systems
    • work with clients to carry out rapid cleaning and disinfection of those cooling towers they were contracted to manage
  • work with the Department of Health to review satellite imagery of the investigation area to attempt to identify potential unregistered cooling towers and other potential sources and inspect as required
  • undertake follow-up inspections of sites with:
    • unregistered cooling towers
    • systems that were visibly unclean
    • systems with poor laboratory results.
Equipment requirements

Equipment that may be necessary to support outbreak investigations include:

  • personal protective equipment (See AS 3666-1990: respirator, disposable overalls)
  • 250mL Sterile Bacteriological Water Sample Bottles - with thiosulphate added
  • thermometer Lovibond Comparator capable of testing for bromine, chlorine and pH
  • torch and spare batteries
  • car refrigerator or polystyrene 6-pack coolers and ice bricks Communication equipment (Portable telephone; charger)
  • 3-4m Ladder and access to larger ladders
  • note book, forms, orders, folders, sample submission cards and other stationary
  • screw drivers (flat and phillips head), pliers and shifting spanners Digital camera

Note: Some of this equipment e.g. ladders for access may be available on site. Ensuring accessibility for inspection of cooling towers is a requirement under the Australian Standards.

Last reviewed: 25-05-2020