Preventing Legionnaires' disease

Preventing Legionnaires' disease

Mandatory notification

To control Legionnaires' disease the City of Sydney maintains a register of water-cooling systems in premises (including cooling towers) and warm-water systems in hospitals and nursing homes. Owners and occupiers who install and operate such systems must notify the City under the Public Health Act 2010.

Legionnaires' disease is a potentially fatal type of pneumonia caused by Legionella, a bacteria that may also cause a flu-like condition called Pontiac fever. These conditions can affect everyone but vulnerable groups who can be more susceptible include older people with existing health problems such as respiratory disease or if they're taking immune-suppressant drugs, heavy smokers and heavy drinkers.

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 6 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.
Levels of Legionella detected Action to be taken
Less than 10 colony forming units/millilitre No action required: effective maintenance practices in place
Up to 100 colony forming units/millilitre Maintenance practices may not be satisfactory: follow-up testing required
100 to 1000 colony forming units/millilitre

Potentially hazardous situation: maintenance procedures to be re-evaluated including current disinfection process, follow-up testing required

More than 1000 colony forming units/millilitre

Serious situation: shut down system for decontamination, undertake follow-up testing when returned to service


The City can order a system be maintained or shut down if sampling finds evidence of Legionella. If you no longer use a cooling tower, it must be drained and the City should be notified. Failure to comply with the requirements can result in fixed penalty notices being issued for each system and/or prosecution.

To register a water-cooling or warm-water system or update information on the register, please download the application form below and fax it to our Health and Building Unit on 02 9265 9750.


The City holds free workshops for anyone who operates a water-cooling system in the area. This is a simple way to get cooling tower safety messages across to owners, occupiers and building managers.

The course is an excellent resource on hygiene with practical tips and advice on record keeping and preventing the spread of Legionella.

Making sure that building managers have the right skills and knowledge will help you to meet your legal obligations. Better knowledge and practices will:

  • prevent an outbreak of Legionella
  • improve record keeping
  • help you to avoid heavy fines or even imprisonment.

Upcoming event dates will appear on this site, or you can contact the City at the number below.


Standards and Policy, Health and Building
02 9265 9333


NSW Health: Legionella control

Last updated: Monday, 30 November 2015