Cooling Towers and Legionella Control

Council is required by law to keep a register of water cooling and warm water systems.

Cooling towers are defined as a ‘regulated system’ under the Public Health Act 2010. During their operation they create a warm environment which is favourable to the growth and proliferation of legionella and other bacteria. For this reason, the Public Health Act 2010 and Public Health Regulation 2022 specify requirements for cooling towers and other regulated systems to minimise the risk of legionella outbreaks.

The Legionella bacteria can cause a type of pneumonia (an infection of the lung), which can be fatal, known as Legionnaires disease and/or Pontiac fever (a mild flu-like illness). The disease has an incubation period from 2 to 10 days for the symptoms to develop after inhaling the bacteria. The legionella bacteria are transmitted through aerosols.

Outbreaks of Legionnaires disease occur from time to time but are preventable. Legionella bacteria can grow in poorly operated and maintained water-cooling systems and warm-water systems, particularly those systems which are not maintained in a clean condition and continuously treated with a biocide to control Legionella bacteria, algae and biofilms. For more information, download the Legionnaires Disease Fact Sheet or visit the NSW Health website.


The Public Health Regulation 2022 requires a performance based or risk management approach to managing cooling water systems.

The Public Health Regulation 2022 has recently been amended to require a performance based approach to managing water cooling systems. This allows each system to be managed according to its risk of Legionella contamination.

Building occupiers are required to ensure that the following six safeguards are in place for their cooling water systems:

  • Risk assessment of Legionella contamination, documented in a Risk Management Plan (RMP) – every five years (or more frequently if required)
  • Independent auditing of compliance with the RMP and Regulation – every year
  • Provide certificates of RMP completion and audit completion to Council
  • Sampling and testing for Legionella and heterotrophic colony count – every month
  • Notifying reportable laboratory test results (Legionella count ≥1000cfu/mL or heterotrophic colony count ≥5,000,000 cfu/mL) to Council
  • Displaying unique identification numbers on all cooling towers.

The NSW Guidelines for Legionella Control in Cooling Water Systems provides guidance on the safe and effective management of water cooling systems for all stakeholders. It provides guidance on the above requirements.

Approved forms for cooling water systems 

 The Public Health Regulation 2022 requires six approved forms to be used to document certain aspects of managing cooling water systems:


NSW Health has developed a training course on Legionella Control in Cooling Water Systems with TAFE NSW. The course provides an overview of the science relating to Legionnaires’ disease outbreaks, cooling water management, and the roles, responsibilities, and requirements under the Public Health Regulation 2022.

Completion of this course is a requirement for approval to conduct audits of cooling water systems. Occupiers and building managers would also benefit from completing this course.