Health authorities are working hard to contain the most fertile legionella season in recent history after the death of a second man in a little over two months.
The continuing outbreaks has led to a stern warning from health authorities for building owners to clean up their act.
The City of Sydney told owners to keep their cooling towers compliant or risk a hefty fine.
City of Sydney issued a directive to building owners last week reminding them that council officers would inspect and sample the towers and charge a fee.
Cooling towers do not generally need to be cleaned more often than every six months in NSW.
But dozens of people have contracted legionnaires' disease this year, with more cases notified between January to April than any year since 2012.
A spokeswoman for NSW Health said additional tests were being performed on four cooling towers.
"NSW Health and the City of Sydney have taken action on all cooling towers that tested positive for legionella in the investigation area," the spokeswoman said.
"This includes issuing a prohibition notice, an improvement notice and warning letters requiring cleaning and disinfection."
NSW Health has appointed a legionella working group which is reviewing the recent outbreaks and considering whether new prevention measures need to be introduced.