Water sources

Water supply

Detailed information on Melbourne's water supply system. Information on Melbourne's water storages is updated daily by around 2pm, seven days a week. Visit Melbourne Water for daily updates.

Water sources

South East Water purchase water from our wholesaler, Melbourne Water, who is responsible for harvesting, storing, and treating water prior to its arrival in our system.

A large proportion of our drinking water comes from protected or uninhabited mountain ash forests high in the Yarra Ranges east of Melbourne, where more than 157,000 hectares has been reserved for the primary purpose of harvesting water.

From the uppermost catchments, water flows into Thomson and Upper Yarra Reservoirs where water may be stored for many years before being used. Holding the water for a long period allows the sediments from the forests, washed in by the rain, to settle, providing natural purification. Water from the upper reservoirs is then transferred to Silvan and Cardinia Reservoirs. Upon leaving the reservoirs, it is disinfected by using chlorine to kill potentially harmful micro-organisms and maintain public health. The water is also fluoridated and corrected for pH.

Water stored in Sugarloaf Reservoir is harvested from the Yarra River at Yering Gorge, the Goulburn River via the North-South Pipeline, and Maroondah Reservoir via the Maroondah Aqueduct. It is then treated by coagulation, flocculation and filtration at the Winneke Water Treatment Plant (WTP) before undergoing the same treatment as water from Silvan and Cardinia Reservoirs.

Towns from Bunyip to Lang Lang, the Mornington Peninsula and Cranbourne receive water from the Tarago Reservoir and WTP. The Tarago WTP is a state-of-the-art Dissolved Air Flotation and Filtration (DAFF) and ultraviolet (UV) disinfection water treatment plant Water from the Tarago WTP is fed directly into South East Water’s supply system via the Tarago Westernport Pipeline.

In March 2020, the Minister for Water announced an order for 125 gigalitres (billion litres) of water from the Victorian Desalination Plant. Since 2016, 194 gigalitres of desalinated water has been delivered and mixed with existing water storages.