In 2023-24 the Western Treatment Plant at Werribee received 210,110 ML of sewage and the Eastern Treatment Plant 155,757 ML. That puts about 57% of Melbourne's treated sewage through a single site, against about 43% at Bangholme.
Two trunk sewers, two renewal projects
Two trunk sewers feed the western plant. The Hobsons Bay Main Sewer, built in the 1960s, carries about 30% of Melbourne's wastewater; its A$206 million duplication and rehabilitation is expected to finish in late 2026. The Western Trunk Sewer carries 57% of Melbourne's sewage, and its A$204 million relining of 4.4 km of tunnel is planned for mid-2027 to late 2029.
Strong service results, stretched capacity
Melbourne Water reported 100.0% E. coli compliance and no spills due to sewerage system failure in 2024-25. Discharge licence compliance was 100.0% at the Eastern plant and 97.1% at the Western plant. Total sewage treated was 320 billion liters in 2017-18 and 366,976 ML in 2024-25, with a peak of 384 billion liters in 2022-23.
Almost 50% more capacity
The A$711 million Resource Recovery and Re-Use Complex, delivered with John Holland and planned to be fully operational in 2029, is intended to raise the western plant's treatment capacity by almost 50%. The project describes the plant's anaerobic lagoons and aerated ponds as overloaded. Separately, the 2026–2031 price determination lists a Western Treatment Plant expansion at A$337 million and an Eastern Treatment Plant augmentation at A$304 million.
How the water supply side compares, who regulates and pays for the system, and where the next opportunities lie are set out in the full report. The full report, Water Systems Overview: Melbourne Water, is available for USD 499 at https://ourfuturewaterintelligence.com/reports/water-systems-overview-melbourne-water. For a free overview, read the Melbourne Water Utility Snapshot at https://ourfuturewaterintelligence.com/utilities/melbourne-water.