NSW Health issues Legionella warning as state reopens

NSW Health is reminding building owners, occupiers, and the water treatment industry of their responsibility to ensure that cooling water systems are maintained effectively in accordance with the Public Health Regulation 2012.

“Businesses reopening their premises during the easing of COVID-19 restrictions should pay particular attention to ensuring their cooling water system servicing regimen is up to date and the disinfection procedure is operating correctly,” says NSW Health.

Occupiers and industry (as the duly qualified person or competent person) are expected to work in partnership to ensure that:

  • Risk Management Plans are prepared for each cooling water system they manage
  • Independent auditing is carried out annually
  • Sampling and testing for Legionella and heterotrophic colony count is carried out monthly
  • Reportable test results of Legionella count ≥1,000 cfu/mL, or heterotrophic colony count (HCC) ≥5,000,000 cfu/mL, are notified to the local government authority within 24 hours of receiving the result from the laboratory.

“Spring is a period of higher risk for the transmission of Legionella bacteria due to intermittent use of cooling water systems during cooler winter months,” says NSW Health. “System start-up after an idle period can cause bacteria to detach from internal surfaces, and aerosolise out of the cooling tower.

“We remind building owners and occupiers and the water treatment industry to remain vigilant and ensure their cooling water systems are maintained to the highest of standards.”

NSW Health has produced extensive guidance on managing risk factors associated with the seasonal operation of cooling water systems, and managing shut-down periods. This is available in section 5.1.2 of the NSW Guidelines for Legionella Control in Cooling Water Systems at

AIRAH also has a suite of cooling tower and Legionella resources at

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