Legionnaires disease

Legionnaires' Disease is spread by legionella bacteria and can be fatal. The legionella bacteria can contaminate and grow in air-conditioning units and people working in or living near buildings can contract legionnaires disease (see more information, below) 

There have been a number of outbreaks in Victoria over the past few years, and the government has introduced legislation (see below) to reduce the risk of contamination. Health and safety reps have a role to play to ensure that the requirements are being complied with.

Action Plan for the Health and Safety Representative

As with all workplace hazards, the hazard should be dealt with in this way:

1. Identification of the hazard
2. Assessment of the risk
3. Elimination or reduction of the risk
4. Review and evaluation of any control strategies.

STEP ONE – Identification of the hazard

• Talk to your members about Legionnaires Disease and its symptoms. Ask them whether they are experiencing problems with the air-conditioning. Consider doing a questionnaire (a sample one can be downloaded from this site).
• Check that your employer has a list of all the cooling towers on the site, and proof that they have been registered. Check also that there is an Risk Management Plant (RMP) and check the records (for inspection, biocide dosing and maintenance) 
• Inspect the air-conditioning maintenance records to discover when the system was last inspected and cleaned.
• Ask that the employer measures workplace temperature and humidity.

STEP TWO – Assessment of the risk

The requirements in terms of what must be tested, acceptable levels and so on, are complex. However if the following has not occurred, then it is impossible to assess the risk: 

• the system is maintained and tested unless it is shut down or is otherwise not in use.
• the water in the system is continuously treated with:
  • one or more biocides to effectively control the growth of microorganisms including Legionella
  • chemical or other agents to minimise scale formation, corrosion and fouling
  • a biodispersant
• immediately prior to a cooling tower system being put into operation for the first time, or following any shut down period of more than one month and at intervals not exceeding six (6) months, a responsible person must ensure that:
  • a chlorine-compatible bio-dispersant is added to the recirculating water; and
  • the recirculating water is disinfected; and
  • the interior of each cooling tower in the cooling tower system is cleaned; and
  • the recirculating water is re-disinfected.

• the system must be inspected and serviced at least once a month to ensure it is operating without defects
• a water sample must be taken from the cooling tower system at least once each month and sent to a NATA approved laboratory  to test for heterotrophic colony count (HCC)
• a water sample must be taken from the cooling tower system at least once every three months and sent to a NATA approved laboratory to test for Legionella.
• maintenance and testing records must be kept for 12 months and can be produced to an authorised officer from the Health Department on request.

Warning: If any of your members have flu-like symptoms and you discover the air-conditioning system has not been cleaned for some time, or testing has not been carried out as per the regulations, call your Union and the Department of Health immediately on 1300 650 172 (free call in Victoria except with mobile phones) immediately. Contact details for regional offices on this page.

STEP THREE – Elimination/reduction of the risk

Reducing the risks associated with the air-conditioning system should involve:

1. Providing all information you have gathered under Steps One and Two to the employer representative and your co-workers.
2. In consultation with the union delegate, arranging a meeting with management to discuss the problems you have identified and agree on a control plan.
3. If you cannot agree, then reporting back to the members. The next step may be to serve a PIN or raise the issue at the Health and Safety Committee. You may also contact a WorkSafe inspector for advice.
4. If you have reached agreement, setting a time frame for each action item to occur.

STEP FOUR - Review

The fourth step is to review the success of the actions taken to fix the air-conditioning problems. This may involve discussions with management and members and a follow up questionnaire survey might be helpful. Consider negotiating an Air-conditioning Policy with your employer. Contact your union to see if they have a model policy.

Request that the annual audit be tabled at the OHS Committee for review and discussion. HSRs must be involved in documenting the review. 

If the annual review is not conducted by third parties or the water treatment provider, once a year the health and safety committee meeting should review the data. 

The minutes of the health and safety committee meeting could constitute part of the documentation of the annual review.  

The questions the committee needs to ask, and have answered, in the Review are:

1. Have all the services, inspections, cleans and water testing of HCC* and Legionella counts been carried out in accordance with the operational program spelt out in the Cooling Tower Risk Management plan/s (RMP)?
   
   * Heterotrophic colony count (HCC) is used as an indicator of water quality in cooling tower systems. 
   
   
2. Have the HCC and Legionella results indicated conformance with the relevant benchmarks?    If not then changes need to be made to ensure conformance.   Where HCC or Legionella counts exceeded benchmarks then maybe the frequency of tower cleans needs to be changed and the RMP operational program be upgraded.
   
   
3. Are there going to be any changes to the workplace or environment nutrient material which may affect the towers? If so, then more frequent cleaning may be needed, that is, a change to the RMP.

Legal Standards

The employer has a duty under the Victorian Occupational Health and Safety Act (2004) to provide and maintain for employees, as far as practicable, a working environment that is safe and without risks to health. This includes providing safe plane, a safe system of work, information, training, supervision, and where appropriate personal protective equipment. The employer also has the duty to monitor conditions at the workplace, and to monitor the health and safety of employees.

There are a range of Victorian regulations that specifically seeks to limit the occurrence of Legionnaire's Disease. This follows the occurrence of a large number of cases of legionnaires disease due to contaminated air-conditioning units. The regulation of cooling towers is under the Public Health and Wellbeing Regulations 2019 (under the Public Health and Wellbeing Act 2008 - PHWA).

The regulations cover a range of measures to prevent and respond to the spread of infectious diseases and minimise public health risks associated with certain businesses, such as aquatic facilities, tattooists and businesses that perform skin penetration procedures. Included in these regulations are important changes concerning the regulation of cooling towers and warm water systems for the control of Legionella. 

The Department of Health has information on different sections of the regulations relevant to the control of legionella:

• Aquatic facilities
• Cooling tower systems
• Legionella risks in certain premises (water delivery systems)

In addition to the PHWA, there are the Plumbing Regulations 2018 [these can be downloaded here]. 

All land owners to register all cooling tower systems with the Department of Health, and renew these registrations annually. In addition to registering a cooling tower system, the owner is also required (under the Public Health and Wellbeing Act 2008) to ensure that a risk management plan (RMP) is prepared and exists in respect of the cooling tower system anytime it is in operation. 

The Department of Health has powers of prosecution under the Public Health and Wellbeing Act 2008 concerning all offences that relate to Legionella controls, including the failure to register a cooling tower system, not having an RMP prepared reviewed or audited. Officers of the Department of Health are authorised to take enforcement action and have powers of entry to investigate potential contraventions.

RMPs must specify how five critical risk factors, including stagnant water and nutrient growth, will be managed. The RMP must be audited annually by a person accredited by the Department of Human Services. (Department of Health Guide to developing cooling tower Risk Management Plans) 

People who own, manage or control cooling tower systems ('business owners') have maintenance and cleaning and record-keeping requirements. They must also carry out monthly water tests for hetertrophic colony counts (HCC) - levels of 100,000 or more are unacceptable.

More Information

What is Legionnaires Disease?

Legionnaires is a type of pneumonia (an acute infection of the lungs). The early signs are like having the flu: headaches, fever, chills, muscle aches and a dry cough. This is usually followed by shortness of breath. Sometimes sufferers may have diarrhoea, mental confusion and kidney failure. It can be fatal.

How is Legionnaires Disease caught?

Legionella bacteria are widespread in the environment and commonly found in natural water courses and soils and so can contaminate and grow in other water systems such as: air conditioning cooling towers, evaporative condensers, and hot and cold water services. Other potential sources include: potting mix, humidifiers, spa and whirlpool baths, showers and ornamental fountains.

People can catch the disease by breathing in very fine droplets (aerosols) of contaminated water that contain the bacteria. Workers in the building with the contaminated airconditioning system are at risk, as well as the people who live in the area. The disease cannot be passed from one person to another, nor caught by drinking Legionella contaminated water.

Who is at risk and how much of a risk is it?

Large numbers of workers are at risk:

• workers in air-conditioned buildings, including office staff, cleaning staff and security staff
• staff in air-conditioned venues such as hotels, museums, aquariums, gaming venues
• building maintenance workers (such as mechanics, electricians, etc)
• air-conditioning company workers

Codes of Practice and other information:

• Victorian Government Department of Health has information on Legionella, including this page.  
• AS 1668 series: on air-conditioning and ventilation; and AS3666 series: on Air-handling and water systems of buildings - Microbial control. Covers the Design, installation, commissioning, operation and maintenance of these systems.
• Code of Practice from Western Australia - Prevention and Control of Legionnaires Disease (2014)
• NSW Guidelines for Legionella Control in Cooling Water Systems
• Office health and safety, and also available free of charge from WorkSafe Victoria.
• From the UK's occupational health and safety regulator, the HSE has lots nof resources on the topic:
  
  • a webpage on Legionella and Legionnaire's Disease,
  • FAQs
  • resources such as: Management of the risks from legionella in cooling towers and evaporative condensers
  • Technical guidance
  • The HSE also has an Approved Code of Practice L8: Legionnaires' Disease - The control of legionella bacteria in water systems, which sets out an effective approach to control. 
    The information is revised and updated regularly. 
• FAQ: Temperature and Humidity in Offices

Last amended January 2025