WoSUP Wonthaggi!

Planning for Growth  – Wonthaggi Sewerage Upgrade Project

Wonthaggi’s wastewater treatment plant has been serving the community well for over 50 years. Located about 2.5km west of the town centre, the lagoon system treats wastewater from Wonthaggi, Kilcunda, and Dalyston to strict standards set by the Environment Protection Authority (EPA).

Wonthaggi and the surrounding areas are growing rapidly, with population forecasts predicting an approximate 30% increase by 2036. The treatment plant will reach capacity in the next 5-10 years. To ensure the region has the infrastructure needed to support future growth, South Gippsland Water is planning a significant upgrade to the Wonthaggi treatment plant.

A new mechanical treatment plant will be able to process greater volumes of wastewater and achieve a better quality of discharge.

The Wonthaggi Sewerage Upgrade Project (WoSUP) is a major infrastructure initiative that will be delivered in stages over several years. Planning and design are underway with a range of technical investigations being conducted to explore how the project can deliver the best environmental, social, cultural and economic outcomes.  

South Gippsland Water has partnered with consulting firms GHD and RM Consulting Group (RMCG) for technical studies and stakeholder engagement.  

A key project goal is to increase resource recovery, particularly through water reuse options. This could reduce reliance on the ocean outfall and make better use of our valuable resources. Due to the area’s high rainfall, re-use options have been challenging to implement in the past, and all possibilities are currently on the table.   

Project Timeline:

2025–2026: Planning, technical studies, stakeholder consultation, and initial design.

By 2031: Upgrade of the treatment plant from a lagoon-based system to a modern mechanical treatment facility.

By 2036: Upgrade of the transfer pipeline, which carries treated water from Wonthaggi, Cape Paterson and Inverloch treatment systems to the ocean outfall.

At this stage, the current ocean outfall will not be changed. The outfall operates and is monitored in accordance with EPA licence conditions.      

Community members, local groups and stakeholders are encouraged to get involved and help us refine our plans and design. South Gippsland Water and consultants RMCG are visiting communities and meeting with interest groups and stakeholders throughout the region until October 2025.  

For more information, to organise a project briefing for your group, or to share your view, get in touch with our project engagement team. 

Email us at wosup@rmcg.com.au or call 0456 774 170.