South East Water’s major upgrade at the Mount Martha Water Recycling Plant has reached a significant milestone, with construction of the wastewater treatment plant now past the halfway mark on works designed to improve capacity, resilience and long-term service reliability.
The project is addressing constraints in the plant’s secondary treatment system, a critical component as population growth and climate pressures place increasing demands on wastewater infrastructure across the Mornington Peninsula.
Why the Mount Martha upgrade is needed
Communities serviced by the Mount Martha facility, including Mount Martha, Mount Eliza, Mornington, Somerville, Baxter and Pearcedale, are forecast to grow by around 49 per cent by 2050.
Without upgrades, this level of growth would place sustained pressure on treatment capacity, particularly during wet weather events when inflows can rise sharply.
Clarifier performance plays a central role in managing these peak conditions by removing solids efficiently and maintaining stable downstream treatment processes.
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What the works involve
South East Water’s industry delivery partners, Beca, Fulton Hogan and Interflow, have completed the base slabs for two new clarifier tanks.
Clarifiers are large settling basins that allow solids to separate from wastewater, improving treatment efficiency and reducing the risk of system overload.
Once complete, the additional clarifier capacity will help the plant manage higher flows during heavy rainfall, improving resilience and reducing the likelihood of spills that could impact local waterways.
Reducing risk and protecting waterways
South East Water General Manager Liveable Water Solutions Charlie Littlefair said increasing capacity is essential to maintaining safe and reliable operations as demand grows.
“By increasing the plant’s capacity, we can reduce the risk of spills and protect local waterways,” Littlefair said.
“We’re investing in infrastructure that supports one of Victoria’s fastest-growing communities while meeting the challenges of a growing population.”
The upgrade forms part of a broader strategy to ensure wastewater systems remain robust under both population growth and more intense rainfall events linked to climate variability.
Part of a broader capital program
The Mount Martha works are one of South East Water’s ten major projects outlined in its Price Submission for 2023–28, reflecting the scale of investment required to meet future service expectations.
Across its service area, South East Water is investing $2.1 billion between 2023 and 2028 in capital projects to support growth, climate adaptation, regulatory compliance and rising customer expectations.
In 2024–25 alone, this program included more than 14,700 kilometres of water pipes, 1,500 kilometres of recycled water pipes and 11,600 kilometres of sewer pipes across the network.
What comes next
Construction on the Mount Martha clarifier upgrades is progressing toward completion by the end of 2026.
Once finished, the upgraded facility will provide greater operational flexibility, improved wet weather performance and a stronger platform for servicing the Mornington Peninsula’s future population.