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Monday November 2, 2026 
2 November 2026
Sydney Water is currently in the process of planning a critical overhaul of the Willoughby Submain, a vital subterranean wastewater pipeline servicing households and businesses across Artarmon, Cammeray, Crows Nest, St Leonards, Naremburn, North Sydney, and Willoughby.
Driven by population growth, the infrastructure upgrade aims to boost capacity, improve environmental protections, and ensure long-term service reliability for the lower North Shore.
The project will include the installation of roughly three kilometres of new wastewater piping buried at an average depth of 40 metres. To minimise above-ground disruption, engineers will construct the majority of the new route using underground microtunnelling technology, with shallower connection points linking directly into the existing Sydney Water grid. Temporary surface work sites will be established along the corridor to construct shafts, manage tunnelling operations, and facilitate crucial system connections.
At its deepest point, roughly 60 metres beneath ANZAC Park, the new submain will merge into the Northern Suburbs Ocean Outfall Sewer (NSOOS). Serving as an arterial trunk line running from Blacktown to the Manly treatment facility, NSOOS transports approximately 25 per cent of Sydney’s daily wastewater, covering roughly 1.7 million residents across the northern and western suburbs.
Preliminary site investigations commenced in June 2026, with the project currently in the environmental assessment phase and community consultation phase. Sydney Water expects to award the primary construction contract by late 2026, with major works scheduled to begin in early 2027 and target completion in late 2028.