Water storage reservoirs

Get to know Melbourne’s 10 major reservoirs, which store water collected from the catchments and supplied by the Victorian Desalination Plant.

A reservoir is a large natural or artificial water storage, often formed by building a dam across a river. Together, our 10 major reservoirs can store up to 1,812 billion litres of water, and vary in size from the smaller O’Shannassy (3 billion litres) to the massive Thomson (1,068 billion litres).

We also manage 38 smaller service reservoirs dotted around Melbourne, which store water for 1-2 days so there’s always some available to meet demand.

How full are our reservoirs?

For daily data on the current state of our storages – individually and overall – check out our water storage levels web app.

Map of Melbourne's major water reservoirs, mains and aqueducts.
Map of Melbourne’s major water storage reservoirs: click to enlarge.

Reservoir types

Our major reservoirs fall into two categories: on-stream and off-stream.

On-stream reservoirs

On-stream reservoirs are filled by rivers or rainfall that runs off the nearby forested water catchments.

Reservoir​ Water source Supplies

Capacity (GL)​

Thomson​ Thomson State Forest and a small part of Baw Baw National Park Upper Yarra Reservoir ​1,068
Upper Yarra​ ​Yarra Ranges National Park, Thomson Reservoir Silvan Reservoir ​200
Tarago​ ​Bunyip State Forest Melbourne’s southeast 37​
Yan Yean ​Toorourrong catchment, Silvan Reservoir, Winneke treatment plant Melbourne’s north ​30
Maroondah ​Watts River catchment and Graceburn Creek Sugarloaf Reservoir ​22
O’Shannassy ​O’Shannassy River and Smith Creek Silvan Reservoir ​3

Note: GL = gigalitres (billion litres)

Off-stream reservoirs

Off-stream reservoirs receive water from on-stream reservoirs or other sources, like the North-South Pipeline and Victorian Desalination Plant.

Reservoir​ Water source Supplies Capacity (GL)​
Cardinia​ Silvan Reservoir, Victorian Desalination Plant ​Melbourne’s southeast, Silvan Reservoir ​287
Sugarloaf Maroondah Reservoir, North-South Pipeline ​Melbourne’s north, east and centre ​96
Silvan​ Upper Yarra, O’Shannassy and Thomson reservoirs ​Most of Melbourne ​40
Greenvale​ Silvan Reservoir Melbourne’s northwest and west ​27

Note: GL = gigalitres (billion litres)

Managing our storages

Some of our reservoirs are connected to each other, so we can move water between them when we need to. This requires us to navigate a dynamic situation: meeting demand for water in different areas, which can change hourly, while dealing with yearly and seasonal variations in availability – from long, dry periods to wetter years. In practice, this could mean moving water out of a reservoir so it can fill up during heavy rain, or keeping its water levels low while its dam is being maintained.

Watch the following video to see how it’s done:

We know drought can creep up on us quickly, so its important we keep our water storages topped upThat’s why desalinated water is critical role to securing our water supply: building a buffer in our storages each year, which can take the pressure off during drier periods and droughts.

Last updated:
24 February 2022