The Eastern Treatment Plant in Bangholme on the eastern side of Port Phillip Bay is one of Melbourne's two major sewage treatment plants. It receives around half of Melbourne's domestic sewage and industrial wastewater. Currently this wastewater is treated to Environment Protection Authority standards before being either reused or discharged to the ocean near Gunnamatta Beach on the Mornington Peninsula.

An upgrade of the plant will begin in 2009 and be completed by 2012. All water will be treated to tertiary standard, producing about 100-130 billion litres of Class A recycled water for non-drinking purposes annually.

Potential uses for the recycled water include industrial, agricultural, environmental and residential for car washing and toilet flushing. Existing recycled projects, such as the Eastern Irrigation Scheme, already use about 15 billion litres of recycled water from the plant and will continue this after the upgrade.

A Business Case investigated two large-scale options for using more of the recycled water after the plant upgrade and found both were too expensive. Localised, cost-effective projects are now the focus for using more of this water.

The options investigated by the business case were:

• substituting recycled water for environmental flows for the Yarra River, by piping the water to the river below Yering Gorge, allowing more fresh water to be retained in Melbourne’s storages
  
• using recycled water for industrial purposes in the Latrobe Valley, particularly power generation, by piping the recycled water to the valley and freeing up the river water currently being used for cooling power plants.

The Business Case Executive Summary is available below:

Recycled Water Business Case (PDF~450kB)

More information on the Eastern Treatment Plant Upgrade is available from the Melbourne Water website.