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Sunbury Recycled Water Plant Upgrade (Completed)

We upgraded the recycled water plant that services Sunbury and Diggers Rest.

Project snapshot

Town(s): Diggers Rest, Sunbury

Status: Complete

Cost: $53 million project over 10 years for upgrade, operation and other costs

Expected Completion Date: June 2019

Work is now complete on the upgrade to the Sunbury Recycled Water Plant.

The plant’s treatment capacity has been upgraded from 5.9 million litres per day to 9.2 million litres per day, an increase of over 50 percent. The upgrade is necessary to cater for the growth in Sunbury and Diggers Rest, which are expected to grow significantly in the coming years.

The $53 million upgrade is also the most significant capital works project in Western Water’s history. Over 250,000 personnel hours were spent upgrading the plant, which included contractors, subcontractors and operations staff.

Who undertook the upgrade?

The upgrade was undertaken by Downer Pty Ltd, who were awarded the design, build, operate and maintain contract.

The project was announced by the Minister for Water, the Hon. Lisa Neville in February 2016, with construction commencing in October 2016.

The first stage of works was completed in March 2018 and included construction of the membrane bioreactor tank, inlet works, centrifuge and odour control facility.

Stage Two works featured refurbishment of old parts of the plant, rehabilitation of some existing in-ground tanks, construction of an outfall pipeline to Jacksons Creek, site landscaping and other minor works. These works were completed December 2018.

The plant then went through a 90-day ‘proof of performance’ test’, where engineers thoroughly tested the plant to ensure it operated as required.

In April 2019, the plant received a certificate of commercial acceptance, confirming works had been assessed as being complete.


Despite significantly increasing its treatment capacity, the upgraded plant will operate within the same footprint, thanks to an innovative design.

The new plant is more energy efficient, with improved environmental performance, including:

  • a new disinfection process that means chlorine will no longer be discharged into nearby Jacksons Creek
  • reduction of nitrogen and phosphorous levels discharged to Jacksons Creek, which will help mitigate against unwanted plant growth, including algal bloom in waterways
  • better odour control with the construction of new odour control facilities
  • improved stormwater treatment, with site runoff captured and treated separately
  • better management of wet weather flows to site.

How has was the community informed?

The local community was engaged throughout the project, including prior to and during construction.

Residents near the plant received letters and project update newsletters, and information was published on our website, Facebook and Instagram.

The Sunbury Recycled Water Plant Project Reference Group also contributed significantly. Formed in 2014, and consisting of residents and community group members, they provided valuable feedback over the course of the project.

Project updates