Sydney Water says up to 12,000 food businesses in Sydney's southwest might be dumping fats, oils, and grease (FOGs) illegally into the sewage system. This pollution feeds a huge fatberg at the Malabar sewage plant, which could be as large as four buses. The problem links to more food businesses opening and changes Sydney Water made in 2017 to its Wastesafe program. The program shifted to digital reporting with fewer inspectors, allowing some businesses to "fly under the radar", critics say. A secret August 2025 Sydney Water report, seen by Guardian Australia, revealed a major build-up of FOGs in a part of the Malabar plant that handles sewage to the ocean. When pumping pressure changed, the fatberg broke up, releasing balls of fat and waste that closed Sydney’s beaches in late 2024 and early 2025. The report found FOGs had risen by 39% over 10 years and volatile organic compounds by 125%. It also noted that up to 12,000 retail food businesses might operate in the Malabar area without Sydney Water’s approval, contributing to the pollution. Sydney Water started the Wastesafe scheme in 1991, requiring food businesses to have approved grease traps and regular cleaning. In 2017, the system moved to a digital model where transport companies report grease collections by scanning barcodes. Sydney Water now has 12 inspectors working with food businesses, but fewer than before. Brett Lemin, head of the Waste Contractors and Recyclers Association of NSW, said, "It’s very hard to police people who aren’t even registering for the Wastesafe system." He added, "There are great people in the food industry who are doing the right thing, but it’s very easy to fly under the radar." Sydney Water said the program’s key rules stayed the same despite system changes. Restaurant and Catering Australia president John Hart said he was surprised by the 12,000 figure and pointed out food businesses need council approval and grease traps. University of Sydney water expert Prof Stuart Khan said 12,000 unregistered food businesses in Malabar’s large catchment was "not outrageous." A study in Bondi also found over 300 unapproved food businesses polluting sewers, suggesting the bigger Sydney area has a large problem. Sydney Water said this Bondi figure underestimates issues in other areas like Malabar. The growing number of unregistered food businesses is adding to Sydney’s sewage fat problem, making efforts to control pollution tougher and risking public health and beach closures.