A colossal mass of congealed fat, oils, and grease, potentially as large as four Sydney buses, has been identified as the likely source of the pollution incidents that forced the closure of iconic Sydney beaches last year.
The Inaccessible 'Dead Zone' and a Multi-Million Dollar Dilemma
According to a confidential report obtained by Guardian Australia, the giant 'fatberg' is lodged within an inaccessible dead zone at Sydney Water's Malabar deepwater ocean sewer outfall. The document, dated 30 August 2025, was prepared for the New South Wales Environment Protection Authority (EPA).
The report states that addressing the problem directly would necessitate shutting down the 2.3-kilometre offshore outfall for maintenance. This would mean diverting sewage to a 'cliff face discharge' point, an action that would force the closure of Sydney's beaches for several months. The report acknowledges this approach has "never been done" and is "no longer considered acceptable".
How the 'Poo Balls' Washed Ashore
The working hypothesis detailed in the report suggests that fats, oils, and grease (FOG) have accumulated in a 300-cubic-metre chamber behind a bulkhead door. This area is not designed for routine maintenance and is usually submerged.
The report links two specific incidents to the dislodgement of this material:
- 15 October 2024: A four-minute power failure at the plant stopped raw sewage pumping. The subsequent rapid restart of high-flow pumps is believed to have sheared off part of the fatberg, leading to debris washing up on Coogee beach.
- 11 January 2025: A similar pressure change due to wet weather likely caused another sloughing event, resulting in further pollution.
Despite initially denying responsibility in November 2024, Sydney Water later acknowledged evidence narrowed the origin of the debris to within the Malabar system. The report reveals that FOG levels in the Malabar wastewater have surged by 39% over the past decade, with volatile organic compounds skyrocketing by 125%.
Limited Options and a Future $3bn Fix
With full removal deemed impractical, Sydney Water's current strategy involves extremely risky cleanouts of the accessible section. In April 2025 alone, 53 tonnes of accumulated FOG and debris balls were removed.
The water corporation plans public education campaigns and a trade waste program targeting an estimated 12,000 food businesses potentially operating without proper waste approvals in the Malabar catchment area.
Following inquiries about the secret report, NSW Water Minister Rose Jackson announced a $3 billion investment program over the next ten years aimed at the Malabar system. The plan is designed to reduce the volume of wastewater discharged via the ageing ocean outfall.
Environmental advocates, like Jeff Angel from the Total Environment Centre, argue this incident highlights the need for a fundamental overhaul. "The outfalls are old school technology," Angel stated, advocating for higher treatment levels and significantly increased water recycling to conserve resources and protect coastal waters.
The EPA confirmed it is working with Sydney Water on a removal program for the bulkhead build-up and is considering licence variations, expected by mid-February.
