Sydney Water proposes 70-million-litre daily wastewater discharge into Parramatta River

The proposal involves a new wastewater treatment facility in Sydney's west at Camellia-Rosehill, connected by a 5.3-kilometre largely tunnelled pipeline to an outlet at Meadowbank Park. Project delivery lead Caine Mertens said the water would undergo advanced treatment, including reverse osmosis, making it cleaner than the current river water and improving local water quality.

"The facility will treat wastewater to an advanced standard using reverse osmosis before releasing," Mertens told the ABC. "Water in this project will be treated to a very high level with lots of safeguards, lots of redundancy."

Sydney Water says the existing Northern Suburbs Ocean Outfall Sewer and North Head Water Resource Recovery Facility — which process wastewater for about 1.7 million people across the city's western and northern suburbs — will reach capacity by 2031. The new facility is needed to support the additional 230,000 people forecast to live in the area over the next 30 years.

"This is all about relieving that pressure on our wastewater system," Mertens said.

However, the proposal has drawn criticism from experts. Ian Wright, a former Sydney Water scientist who spent 18 years with the company and is now an associate professor and water science researcher at Western Sydney University, expressed strong concerns.

"To put treated water, treated from sewage, into the Parramatta River is actually unbelievable to me," Professor Wright said. "Pumps break, filters block. All kinds of things can happen, so you may be able to achieve high quality most of the time, probably not all the time."

The project is being assessed as a state significant development application by the Department of Planning, Housing and Infrastructure.

Why This Matters

The discharge site at Meadowbank Park is near recently reopened swimming spots at Putney Beach, raising concerns about recreational water quality and public health.
The proposal highlights the tension between Sydney's rapid population growth and the need for wastewater infrastructure, with the existing system expected to reach capacity by 2031.
The outcome could set a precedent for how Sydney manages wastewater disposal in urban rivers, potentially affecting other waterways in the city.

Background

The Parramatta River has been the focus of a long-term cleanup effort, with the NSW government investing in reopening swimming sites as part of a broader revitalisation. Sydney's wastewater system, primarily designed for ocean outfall disposal, is increasingly strained by population growth in western and northern suburbs. The Camellia-Rosehill proposal involves advanced treatment technology, including reverse osmosis, but critics argue that reliance on mechanical systems carries inherent risks.

Key Perspectives

Sydney Water (Proponent): The project is essential to prevent the existing wastewater system from being overwhelmed by population growth. The treated water will be cleaner than the river's current state and will improve overall water quality. Recreational users and local residents: Those who use the recently reopened swimming areas, such as Putney Beach, are likely concerned about the proximity of treated wastewater discharge and its potential impact on swimming conditions and aesthetics. Critics (including Professor Ian Wright): The reliability of advanced treatment technology is questioned. Mechanical failures such as pump breakdowns or filter blockages could lead to intermittent releases of lower-quality effluent, posing risks to river health and public confidence.

What to Watch

The Department of Planning, Housing and Infrastructure's assessment of the state significant development application and any conditions imposed on the project.
Community consultation responses, particularly from residents and users of Parramatta River swimming sites.
Any further public statements from Sydney Water about additional safeguards or contingency plans for treatment failures.

ZOTPAPER