Water systems

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Where does my water come from?

Legend

 Catchments

A "catchment" is an area of land where, when it rains, water can run in from a creek or stream leading to one of the major water supply dams. There are over 16,500 square kilometres of "catchment area" in Sydney's water system. We sample many of the rivers and streams (inflows) that carry water into the storages from the catchments.

 Dams

There are seven major dams storing Sydney's water. There are also secondary storage dams which hold water, which is available for transfer to the major dams. Water storage dams hold large amounts of water for use over time, particularly in dry conditions. The dams also allow time for many of the "contaminants" which are held in the water as it runs through the catchments, to settle out.

 Water filtration plants

On leaving the dams, the water passes to one of the 9 Water Filtration Plants around the Sydney Water network. The filtration plants are designed to further boost the quality by removing identified contaminants which are set down in each plant's performance targets. These are to ensure the water meets quality and health guidelines.

 Customer supply systems

From the Filtration Plant water enters a complex series of pipes and reservoirs for delivery to homes and businesses. Each Filtration Plant may supply one or more customer supply systems. The Prospect Water Filtration Plant, the largest and most complex, supplies water to around 80 per cent of Sydney.

 Desalination plant

The desalination plant uses reverse osmosis technology to extract fresh water from seawater. After screening and pre-treatment to remove any solids and sediment the water is then pushed through membranes under high pressure. Fresh water passes through the membranes and the remaining seawater concentrate is returned to the ocean. The water is then treated to meet Australian Drinking Water Guidelines and transferred to a tank ready for supply to customers.

Water from the plant is distributed to up to 1.5 million people as part or all of their water supply. This includes the CBD, inner west, eastern suburbs, southern Sydney, parts of the Sutherland Shire and at times as far west as Auburn. Water from the plant was slowly ramped up to a maximum capacity of 250 million litres a day.