The decision to build a desalination plant

In June 2007, Victoria was in the grip of the ‘Millennium Drought’. Melbourne’s water storages were at 29 per cent and reservoirs had fallen by 20 per cent over the preceding 12 months. Stage 3a water restrictions had not stopped the decline in storage levels and the shortfall between supply and demand over the previous 12 months was about 250 GL a year.

Faced with this, the prospect of more prolonged droughts in future years and projected population growth, the Victorian Government decided to build the Victorian Desalination Project (VDP).

The rainfall independent VDP would be capable of supplying up to 150 GL of high quality drinking water a year, or around one third of Melbourne’s annual water consumption.

Despite significant rainfall in late 2016, Melbourne has experienced below long-term average inflows into our storages in 18 out of the past 20 years.Our largest reservoir, the Thomson Dam,has not been full since 1996.

Over the long-term, scientists say there will be even less rainfall, less run-off into our rivers and storages and more severe and prolonged droughts.

We also know that storage levels can drop quickly in a severe drought. In 2006, Melbourne’s water storages dropped from around 60 per cent to 40 per cent in just one year.

Melbourne’s population has risen by 20 per cent since 2007, placing further pressures on our rainfall-dependent storages.

The VDP can deliver up to one-third of Melbourne’s annual demand. The remaining two-thirds still needs to come from water held in our storages. The VDP helps to take pressure off our dams during droughts and helps build a buffer for future droughts in our storages in wetter years.

The plant was not built to be turned on just when our water supply reaches critical levels. Instead its aim is to help make sure that our water supply doesn’t fall to those levels in the first place.

The VDP is connected to the water grid.  The VDP pipeline has six connection points for the three water corporations adjacent to the pipeline – South East Water, Westernport Water and South Gippsland Water. This will enable Cowes, Wonthaggi, Inverloch and Cape Patterson to be supplied water from the Melbourne system or the plant. In the future, Korumburra, Poowong, Loch and Nyora will also be connected to the Melbourne water system via this pipeline.

Geelong has already taken water from the Melbourne system and, subject to trades between water corporations, can just as easily be supplied with desalinated water in the future.

The rapidly growing populations of Sunbury and Melton, already connected to the Melbourne system, can also be supplied with desalinated water.

The project's key environmental elements are:

  • Innovative design that integrates the plant into the coastal landscape through low-profile buildings, dune creation and coastal habitat restoration.
  • Limited carbon footprint by offsetting operational power with renewable energy certificates.
  • Protecting the marine, coastal and estuarine environment by tunnelling under the coast and seabed.
  • Designing the intake and outlet structure to minimise environmental impact.
  • Protecting ecological values near the desalination plant and pipeline and power supply.
  • Boosting Melbourne’s water supply by moving away from fully relying on streams, has complemented work to improve the health of our rivers.

Many of the VDP’s key components have a 50 to 100-year life, which extend beyond the remaining life of the contract with AquaSure (contract ends 2039). The VDP includes the plant, pipeline to Cardinia Reservoir and purpose-built electricity cable, which will be an invaluable resource for the greater Melbourne region and for the period of the AquaSure contract and beyond.

The plant, located on the Bass Coast near Wonthaggi, uses the energy efficient desalination method known as reverse osmosis. It includes energy recovery devices to reduce power usage and long intake and outlet tunnels, which not only draw in seawater but also protect the coast and marine environment by exiting beyond sensitive marine areas. The plant's world–class design includes Australia's largest green roof and it is surrounded by a 225 hectare ecological reserve open for public use.

On 16 May 2017, the Minister for Water announced that the water order from the Victorian Desalination Project for 2017/18 would be 15 GL. The Minister also announced that Melbourne households would not face additional charges on their water bills for the 15 GL order or the 50GL order made for 2016/17. The media release for this announcement can be found here.

On 19 March 2017, the Minister for Water announced that the Victorian Desalination Project had begun delivering the 2016/17 50 billion litre water order. The media release for this announcement can be found here.

On 6 March 2016, the Minister for Environment, Climate Change and Water announced an order of 50 billion litres of water from the Victorian Desalination Project, to be delivered over the 2016/17 Supply Period (1 July 2016 to 30 June 2017). The media release for this announcement can be found here.

Flexible water orders can be made from 0 to 150 billion litres (in set increments) to suit different needs each year.

The Victorian Government has made a minimum water order of 15 GL in 2017/18 and intends to order at least minimum amounts in 2018/19 and 2019/20. This will be at no added cost to water customers with the orders  to be funded from the sale of surplus Renewable Energy Certificates.

A minimum water order per annum provides a range of benefits, including guaranteeing continued water security, better plant and pipeline management and steadier prices for water customers.

The government also has the option of making orders greater than the  minimum if it is appropriate to do so.

The plant, located on the Bass Coast near Wonthaggi, uses the most energy efficient desalination method - reverse osmosis. It includes energy recovery devices to reduce power consumption and long intake and outlet tunnels, which not only draw in seawater but also protect the coast and marine environment by exiting beyond sensitive marine areas. The plant's world–class design includes Australia's largest green roof and is surrounded by a 225 hectare ecological reserve open for public use. More information on the plant can be found here.

The project includes a two-way underground transfer pipeline which connects the plant to Melbourne's water network through a delivery point at Berwick and transfer main to Cardinia Reservoir. Offtakes are included along the pipeline so that areas in South Gippsland and Western Port can access the water from the plant or Cardinia Reservoir if required. More information on the pipeline can be found here.

The project's 87 km dedicated underground power line is predominantly located within the pipeline easement. All operational energy is drawn through this power line and is 100% offset by renewable energy certificates. Fibre optic cables have been installed with the power supply for plant, power and pipeline operations. More information on the power line can be found here.

The project is a Public-Private Partnership with a capital cost of $3.5 billion. The project is a public-private partnership between the State Government and AquaSure, the company contracted to finance, design, build, operate, and maintain the project for 30 years. The plant will be handed back to the State in working order at the end of AquaSure's contract in 2039. More information on project costs can be found here.

The Department of Environment, Land, Water and Planning's Capital Projects Group manages the contract with AquaSure on behalf of the State. Many of the plant's key components have a 50 to 100 year life, and the plant will be handed back to the state in working order at the end of AquaSure's contract (in 2039).