Pathogenic bacteria in urban stormwater drains from inner-city precincts

Stormwater is being harvested for potable and non-potable reuse applications across Australia. Whilst the range of pathogens present in wastewater are well characterised, significantly less is known of the range of pathogens present in stormwater. Pathogen data for stormwater are limited both within Australia and overseas. This, in turn, limits the effective application of the health risk assessment framework to stormwater as this is underpinned by the assessment of hazards and exposure to them. The overall aim of this study is to identify pathogenic bacteria (not indicator organisms) present in stormwater drains from two inner city precincts in a metropolitan city. Eighteen grab samples were collected twice a week from three central Melbourne stormwater drains. Cell culture techniques and microscopy were utilised to identify and enumerate Campylobacter sp., Legionella sp. and Staphylococcus aureus. Results of this study strengthen our understanding of the pathogenic bacteria individuals may be exposed to via different routes of exposure including ingestion, inhalation and dermal contact. This knowledge will inform the assessment of microbial human health risks associated with stormwater reuse and will assist policy makers and regulatory authorities in developing and applying risk management strategies that are protective of human health.