​Cooling water systems must be managed safely in order to prevent the growth and transmission of Legionella bacteria.

Last updated: 01 September 2022

​What is a cooling water system?

Cooling water systems contain one or more cooling towers. These devices are used to circulate cooling water which, in turn, cools the air in refrigeration, air conditioning systems and industrial processes.

A cooling tower reduces the temperature of water through evaporation (evaporative cooling). Cooled water is then piped to an interface with an air-handling system, allowing the water to cool the air. Air ventilation pipes then deliver the cooled air into the building.

Why is the management of cooling water systems important?

Effective management of cooling water systems is essential for protecting public health.

Poorly managed cooling water systems can provide ideal conditions for the growth and transmission of Legionella bacteria.

People can become infected by inhaling fine airborne aerosols generated by cooling towers. Infection may cause Legionnaires’ disease, a serious and potentially life-threatening condition.

What is the Public Health Regulation about?

The Public Health Regulation 2022 (the Regulation) requires all cooling water systems to be managed according to AS/NZS 3666:3:2011 Air-handling and water systems of buildings - Microbial control - Performance-based maintenance of cooling water systems.

This risk management approach requires the individual characteristics and unique risks of each cooling water system to be assessed and controlled.

What does the Regulation require?

The Regulation sets out six key requirements or “safeguards” as part of the risk management approach:

  1. assessing risk of Legionella contamination and preparing a Risk Management Plan (RMP) – every 5 years (or more frequently if required)
  2. independent auditing of compliance with the RMP and Regulation – every year
  3. providing certificates of RMP completion and audit completion to the local government authority
  4. sampling and testing for Legionella and heterotrophic colony count – every month
  5. notifying reportable laboratory test results (Legionella count ≥1,000 cfu/mL or heterotrophic colony count ≥5,000,000 cfu/mL) to the local government authority
  6. displaying unique identification numbers on all cooling towers.

Who are the key stakeholders?

There are several important roles in managing a cooling water system:

  • occupiers must ensure that their cooling water system is managed in accordance with the Act and Regulation. 
  • duly qualified persons manage the cooling water system on a routine basis.
  • competent persons undertake a risk assessment and prepare an RMP.
  • independent auditors conduct audits of compliance with the RMP and Regulation.
  • laboratories that are accredited by the National Association of Testing Authorities test microbial samples.
  • authorised officers have powers to ensure that the above stakeholders comply with the Act and Regulation.
  • local government authorities regulate cooling water systems in their area.
  • NSW Health sets legislation and policy, supports local government authorities, monitors disease, and investigates outbreaks.

What guidance and training is available?

The NSW Guidelines for Legionella Control in Cooling Water Systems explain the new requirements in detail.

This series of factsheets summarises the key information for each stakeholder. The full set of factsheets can be found on the NSW Health website.

NSW Health has developed the Legionella Control in Cooling Water Systems training program together with TAFE NSW. All stakeholders are encouraged to complete this training. The course is compulsory for auditors.

For more information

  • Learn more about the Legionella control requirements.
  • Contact your local council or call your local public health unit on 1300 066 055.
  • Non-English speaker? Call the Translating and Interpreting Service on 13 14 50.​​
Current as at: Thursday 1 September 2022
Contact page owner: Environmental Health