The water supplied by City West Water comes from Melbourne's well established water supply catchment and reservoir system that has provided the city with reliable, high quality drinking water for many years.
This extensive system, managed by Melbourne Water Corporation, lies mainly to the east of Melbourne and includes Thomson Reservoir some 120 km from City West Water's supply area.
City West Water obtains its water supply directly from three major storages within the system. Two of the storage reservoirs - Silvan Reservoir (near Mount Dandenong) and Sugarloaf Reservoir (near Yarra Glen) - are east of Melbourne, with the third - Greenvale reservoir - located to the north (near Somerton).
The supply from Silvan and Greenvale Reservoirs originates from protected, natural catchments (including Thomson and Upper Yarra catchments) where activities such as industry, farming, urbanisation and tourism, which could lead to pollution or contamination of the water supply, are highly restricted. Long storage periods (ranging between months and years) in these pristine reservoirs allow natural sediments to settle to the bottom, ensuring high water quality.
The supply from Sugarloaf Reservoir originates from the upper Yarra River and its unprotected catchment. Water from the Yarra River is pumped into the reservoir, where it is stored for many months before being comprehensively treated at the nearby Winneke Water Treatment Plant, resulting in very high quality drinking water.