Water storage reservoirs

​Our 10 major reservoirs store water collected from the catchments. Together, they have a storage capacity of 1,810 billion litres, and vary in size from the smaller O’Shannassy (3 billion litres) to the massive Thomson (1,068 billion litres).

Melbourne’s water storage levels are expressed as a percentage of the combined capacity of all storage reservoirs. This is more accurate than looking at individual reservoirs because of their vast differences in storage capacity. For example, the amount of water needed to completely fill O’Shannassy Reservoir would only fill 0.3% of Thomson Reservoir.

On-stream and off-stream reservoirs

There are two types of storage reservoirs:

  • on-stream reservoirs are fed by a water catchment

  • off-stream reservoirs receive water transferred from on-stream reservoirs  or other sources - for example Sugarloaf Reservoir, which can receive water from the North-South Pipeline

On-stream reservoirs

Reservoir​ Source of water​ Capacity (billion litres)​
Thomson​ ​Thomson catchment, located in Thomson State Forest and a small part of Baw Baw National Park ​1,068
Upper Yarra​ ​Upper Yarra catchment, in the Yarra Ranges National Park ​200
Tarago​ ​Bunyip State Forest 37​
Yan Yean ​Combination of Toorourrong catchment, Silvan Reservoir and Winneke treatment plant ​30
Maroondah ​Watts River catchment and Graceburn Creek ​22
O'Shannassy ​O’Shannassy River and Smith Creek ​3

Off-stream reservoirs​

Reservoir​ Areas supplied​ Capacity (billion litres)​
Cardinia​ ​Most parts of Melbourne, especially the south and south-eastern suburbs ​287
Sugarloaf ​North, west and central Melbourne ​96
Silvan​ ​Most parts of Melbourne ​40
Greenvale​ ​North-west and west Melbourne ​27

The reservoirs are connected so we can move water around the water supply system, based on factors such as rainfall and demand.

Last updated:
20 November 2019