Sydney’s city streets have become the unlikely setting for a deadly public health scare. In recent weeks, an outbreak of Legionnaires’ disease in the heart of the CBD has claimed a life and left several others hospitalised, with cooling towers now under intense scrutiny.
NSW Health confirmed on 19 April that one person had died and five others had been diagnosed with Legionnaires’ disease. The outbreak triggered an urgent environmental investigation, with officials identifying cooling towers in the area as the likely source. “NSW Health and the City of Sydney have worked together to inspect and sample 10 cooling towers in the area,” the department stated, confirming that disinfection was swiftly carried out to reduce the risk of further exposure.
Legionnaires’ disease is caused by Legionella bacteria, typically found in water systems such as cooling towers, spas and fountains. When these systems aren’t properly maintained, bacteria multiply in warm water, becoming airborne in tiny droplets that people unknowingly inhale. It’s a severe form of pneumonia with potentially fatal consequences, particularly for older people, smokers and those with weakened immune systems.
“Legionnaires’ disease is a high risk because it becomes so easily airborne and can infect people several kilometres from an affected cooling tower. At least one person has died in Sydney due to the outbreak, so yes, it is a very serious infection,” Integrated Biosciences and Built Environment Consortium, technical and managing director Claire Bird (PhD) says.
NSW Health continues to warn that “people can catch Legionnaires’ disease by breathing in contaminated water particles from the air. It cannot be spread from person to person.” The symptoms closely mimic severe pneumonia, with high fever, chills, muscle aches and shortness of breath. Rapid treatment is essential, yet, as this outbreak shows, prevention should always be the priority.
One of the diagnosed patients, still recovering in hospital, described his experience to 9News: “It hit me like a ton of bricks. Within a day, I was in hospital, unable to breathe properly. It’s terrifying to think it came from something as ordinary as a cooling tower.”
And that’s the chilling part—how ordinary these systems are. Cooling towers hum unnoticed atop office blocks. Misting systems cool outdoor diners in summer. Decorative fountains bubble away in shopping centres. Without rigorous maintenance, any of them can harbour this invisible threat.
“Legionella pneumophila, the bacteria that causes the disease, grows in biofilms – unique microbial communities that protect the organisms living there, allowing them to persist over time,” Bird says. “These biofilms thrive where there’s constant moisture. They can be found throughout HVAC systems, posing different risks, especially to immune compromised individuals.”
She explains that temperature plays a key role in the bacteria’s growth. “Cooling towers and stagnant spots in pipework, so-called ‘dead legs’, fall within the bacteria’s favoured temperature range. It also favours areas that remain wet most of the time, making these systems ideal breeding grounds.”
For the cleaning and hygiene industry, this outbreak is more than a distant headline. It’s a stark warning of what happens when vigilance falters. “This incident highlights the importance of building owners maintaining their cooling towers to prevent the growth of Legionella bacteria,” NSW Health’s Dr Jeremy McAnulty stated.
Bird backs this with a clear message: “Be vigilant in the cleaning and maintenance of your cooling towers and test regularly to ensure L. pneumophila is not present. Run hot water above 50 °C through stagnant areas in the system to reduce risk. Insulate pipes, and mix hot and cold water close to outlets to keep more of the pipework outside the ideal range for bacterial growth.”
Those words should echo through every maintenance room and operations manual. Hygiene isn’t a tick-box exercise—it’s a life-saving duty.
