Cooling Towers and Legionnaires Disease

Legionnaires' disease occurs when someone inhales the organism that penetrates deep into the lungs, possibly through a contaminated aerosol from a cooling tower. Legionella can be controlled by proper water treatment procedures and regular cleaning. To safely maintain water cooling systems, business owners must arrange for a competent person to:

  • demonstrate the disinfection process used adequately controls microbial growth
  • inspect the system every month and clean it every six months
  • undertake regular microbiological water testing
  • ensure operation and maintenance manuals are on-hand
  • ensure a log book details all work carried out
  • certify the system each year


Council’s Environmental Health Officer can inspect premises that operate cooling towers and request to see documentation confirming the above requirements. All cooling towers must be maintained in accordance with Australian Standard AS/NZS 3666 "Air Handling and Water Systems of Buildings - Microbial Control." It is available from Standards Australia on 1300 65 46 46.

AS/NZS 3666 is adopted formally in NSW under the Public Health Act and the Public Health (Microbial Control) Regulation. This legislation also adds some further technical requirements. Please see the NSW Government Health website for further information.