Sydney is set to spend $3 billion over the next decade to upgrade its ageing sewerage network following a series of debris ball incidents that forced the closure of iconic beaches.
Thousands of black and grey balls, roughly the size of marbles, washed up on Bondi, Manly, and other major beaches in late 2024 and early 2025, sparking public outrage and environmental concern.
An investigation by the NSW Environment Authority found the balls likely originated from the Malabar deep ocean outfall, a wastewater system servicing nearly two million residents. Analysis revealed the balls were composed of household fats, oils, grease, human hair, and other debris, with oceanographic conditions and weather factors contributing to their formation. Authorities suspect they resulted from 10 or more separate discharge events over the summer.
State Water Minister Rose Jackson said the multi-billion-dollar upgrade program aims to reduce the volume of wastewater needing treatment and discharge while preparing the system for Sydney’s rapidly growing population.
“Sydney is a rapidly growing city and no one wants to see debris balls washing up on our beautiful beaches again – but the truth is our wastewater system needs an upgrade to keep pace with the population,” Jackson said. “For too long, a lack of investment in essential infrastructure in western Sydney has been a handbrake on our housing goals. We can’t undo that overnight, but we’re getting on with the job of clearing this backlog.”
Sydney Water chief executive Darren Cleary said the staged upgrades would ease pressure on the “ageing coastal plant” and prevent sudden spikes in household bills. The first works will target treatment sites at Glenfield and Liverpool in the coming months.
In the short term, Sydney Water is increasing cleaning and inspection of ocean outfall screens, expanding education campaigns on fats, oils, and grease, and tightening controls on high-risk customers.
Cleary stressed that while no single origin point for the debris balls was identified, the upgrades will ensure the system can cope with future population growth and environmental challenges.
With billions earmarked for infrastructure, authorities hope to prevent a repeat of the summer contamination, protecting both Sydney’s coastline and its rapidly expanding communities.
