Imagine a monstrous blob of fat, oil, and grease—the size of four buses—lurking deep beneath Sydney's iconic beaches. This isn't a sci-fi nightmare; it's a very real problem. This 'fatberg' is the likely culprit behind the mysterious 'poo balls' that closed Sydney beaches last year, and it's a problem that can't be easily fixed.
A recent report obtained by Guardian Australia reveals a giant fatberg lurking within Sydney Water's Malabar deepwater ocean sewer. This behemoth, potentially as large as four Sydney buses, is suspected of birthing the debris balls that washed ashore in late 2024 and early 2025, forcing beach closures. The problem? Sydney Water can't easily access this underwater monster, making its size and exact location a mystery.
Here's where it gets even more complicated: Removing the fatberg would require shutting down the outfall, which stretches 2.3 kilometers offshore, for maintenance. This would mean diverting sewage to a 'cliff face discharge,' effectively closing Sydney's beloved beaches for months. The report admits this solution, while drastic, has never been attempted and is no longer considered a viable option.
Sydney Water's deepwater ocean outfall (DOOF) assessment report, dated August 30, 2025, points to a buildup of fats, oils, and grease (FOG) in an inaccessible 'dead zone' as the source of the problem. This accumulation, the report suggests, has led to 'sloughing events,' releasing the infamous debris balls.
And this is the part most people miss: The report traces the first poo ball sightings on Coogee beach in October 2024 to a power outage at the treatment plant, which temporarily halted sewage pumping. The subsequent surge in flow likely dislodged a chunk of the fatberg, sending it on its journey to the shore. A similar event in January 2025, triggered by heavy rain, is believed to have caused another wave of debris ball landings.
Initially, Sydney Water denied responsibility, claiming its system was operating normally. However, after Guardian Australia exposed a secret oceanographic modeling study, the EPA admitted the debris likely originated within the Malabar system, which has been operational since 1990.
The latest report paints a concerning picture. FOG levels in the Malabar system have skyrocketed by 39% in the past decade, while volatile organic compounds (VOCs) from cleaning products, cosmetics, and other sources have increased by a staggering 125%. This toxic cocktail is escaping into the ocean, particularly during heavy rain events.
Is Sydney's sewage treatment system simply outdated? Unlike many cities that employ secondary treatment methods, Sydney relies on primary treatment, which only removes solids. This leaves behind FOG and other pollutants, contributing to the fatberg problem. Cities like Singapore, in contrast, treat their sewage to such a high standard that it can be reused for drinking water.
Sydney Water is taking steps to address the issue, including regular cleaning of accessible areas and public awareness campaigns discouraging the disposal of FOG down drains. They're also planning a trade waste program for food businesses, many of which may be contributing to the problem without proper waste approvals.
While a $3 billion investment program announced by the state water minister aims to reduce wastewater discharge, some argue for a more fundamental shift. Jeff Angel of the Total Environment Centre advocates for modernizing the entire system, emphasizing higher treatment levels and increased recycling to minimize ocean dumping and conserve water resources.
The question remains: is Sydney doing enough to tackle this growing problem? Will the proposed solutions be sufficient, or does the city need a complete overhaul of its sewage treatment infrastructure? What do you think? Let us know in the comments below.
