Due to the growth of our community and industry, the sewage and trade waste flows to our Warrnambool Sewage Treatment Plant have been steadily increasing.

Since the facility was commissioned, the population has grown by about 33 per cent. Based on current forecast growth rates, it could grow by a further 35 per cent over the next 50 years. The plant also treats a large and increasing volume of commercial and non-domestic waste from industry.

Once the sewage and trade waste goes through the treatment process, the resulting liquid is known as treated effluent. At Warrnambool, the majority of this effluent is disposed of via an ocean outfall with around 60 million litres recycled for use within the plant e.g. in the washing of screening processes and for equipment cleaning.

Managing Warrnambool’s residential, commercial and industry sewage and trade waste is a complex and constantly evolving task. It's a balancing act to minimise harm to the environment and ocean users while keeping water and sewer service bills affordable. Additionally, community expectations are changing about our role in improving the environment in which we operate.

The Warrnambool Sewage Treatment Plant has evolved since it was commissioned in 1996, including the addition of new screening and treatment systems. The plant was designed to treat sewage and industry waste, but it needs to respond to everything that is put into the sewerage system, including rubbish and pollutants. Solid materials that need to be managed include items such as cotton buds, rags, dental floss, wipes, sanitary products, and small plastics.

When deciding on options for managing sewage and industry waste in the future, we need to think about a range of factors including:

We're currently upgrading the Warrnambool Sewage Treatment Plant. When the project is finished, sewage and industry waste will go through the following processes:

• Inlet screening facility (five-millimetres).
• Odour control.
• Treatment tanks (aeration, settling and decanting).
• Final effluent (outlet) and screening facilities (one-millimetre).
• Ultra Violet (UV) disinfection.
• Treated effluent is discharged into the ocean mixing zone with minor on-site recycling.

From 2024 to 2026, we'll be developing our Warrnambool Sewage Treatment Plant Effluent Management Strategy which will investigate alternative methods for further treating the sewage and trade waste, and for the disposal of treated effluent. This will be done in a way that balances what's technically possible, what meets community expectations, and what keeps water and sewerage service bills affordable.

We'll use community and stakeholder priorities to determine a short list of options to consider. These will be shared with the community and stakeholders prior to developing a preferred approach and the next steps.