There has been a third outbreak of Legionnaires disease, this time on the northern beaches of Sydney.
Three people have been hospitalised after becoming sick near the Dee Why shopping centre.
The Northern Sydney Local Health District said cooling towers in Dee Why have been checked and cleaned and there "is no need to avoid the area."
This is the third outbreak since early March with authorities immediately looking to cooling towers as the source of the problem.
However, Aqua Technical Services president, Frank Rosa, said cooling towers are not to blame.
"Just as one would not fish for Great Whites in Alice Springs one should focus on the source of Legionella Bacteria (LB), the potable water system," he said.
"Consider that LB are aquatic organisms, they are not ubiquitous in the environment, there must be water.
"Yes, LB has been reportedly able to survive 5-10 km under the right conditions, but the LB must be airborne first.What is common to all the infected cooling towers and closed loop potable water systems? The make-up water, so obviously its the city water mains," Rosa said.
"Unfortunately it is too late for the system mains – the expense would be horrific for Sydneysiders but building owners can, and should, be addressing the issue head-on or face the consequences of adverse litigation with high insurance costs down the road."