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Changing ocean water into drinking water

Sydney's desalination plant is one of the ways we are securing our water supply against the effects of climate change, a growing population and drought.
The desalination plant is powered by 100% renewable energy.  It can supply up to 250 million litres a day which is up to 15% of all our water needs.  Water from the desalination benefits all water users in Sydney directly or indirectly.

Desalination turns seawater into drinking water. Many countries are using desalination as a way of creating a more reliable water supply that doesn’t depend on rain.

For a detailed, interactive guide of the desalination plant and its processes, go on our virtual tour.

How does desalination work?

The wind powered desalination plant uses reverse osmosis to extract fresh water from sea water. The plant contains over 36,000 reverse osmosis membranes, which block particles and salts, so only fresh water can pass through. The remaining sea water is returned to the ocean.

Pre-treating the seawater

Sea water is drawn in from the ocean through a large pipe. It then goes through a screen to remove things like sand or weeds. It sinks down through filter beds to remove smaller particles.


Sea water is desalinated using reverse osmosis. The sea water is forced at high pressure through thousands of reverse osmosis membranes, which are like very fine sieves. They extract fresh water, leaving behind a salty liquid called the sea water concentrate.

Producing drinking water

The fresh water produced by Sydney’s desalination plant is treated to meet the Australian Drinking Water Guidelines. Like all Sydney’s drinking water, fluoride is added to protect teeth.

The drinking water travels through an 18 kilometre pipeline to join Sydney’s water supply system at Erskineville. It can supply to up to 1.5 million people south of Sydney Harbour and as far west as Bankstown. Like drinking water from Sydney’s water filtration plants, the drinking water made by the desalination plant is monitored and tested throughout production.

Seawater concentrate

The left over salty liquid is about twice as salty and two degrees warmer than the ocean when it is returned through a large pipe beneath the seabed.  It is distributed by large diffusers. The sea water concentrate is mixed into the ocean and returns to its normal salt content and temperature within 50-75 metres from the discharge point.

If you would like to know more about the desalination process, you can go on our virtual tour.

Where is the desalination plant?

Map showing the suburbs of Sydney that may recieve desalinated water

 Sydney's desalination plant can supply water to suburbs in Sydney's south, east and west.

The desalination plant is located on the coast at Kurnell in a 45 hectare site which includes a 15 hectare environmental conservation area.

How is desalination powered?

Wind turbines on a hill

Wind turbines at Bungendore offset the plant's energy use.

Sydney’s desalination plant energy use is offset by 100% renewable energy source, wind power. A wind farm with 67 huge turbines is located at Bungendore. This farm increased the supply of wind power in NSW by 700%. This power is put into the electricity grid.

Desalination and your health

Children filling up a jug with water from the kitchen sink

We provide safe, clean drinking water.

Drinking water produced by the desalination plant is monitored and tested in the same way as water from Sydney’s filtration plant.

The desalinated water meets the Australian Drinking Water Guidelines.

Desalination and the environment


The desalination plant was built with a strong focus on the environment. The plant has reduced the transfer of billions of litres of water from the Shoalhaven River system and reduced greenhouse gases generated as a result of pumping this water. It also means no new dams need to be built in the near future.

The wind farm produces more than enough energy to offset the energy used by the desalination plant. The wind farm was a huge boost to green power in NSW and provides an environmentally sustainable way to make up for the power needs of the desalination plant.

Protecting the marine and estuarine environment is also a key priority for Sydney Water. Research has shown that after the seawater concentrate is discharged, the ocean will return to its normal salt content and temperature within 50 –75 metres from the discharge point.

Desalination aerial

Desalination tour

Go behind the scenes at the Sydney Desalination Plant to see how ocean water is turned into drinking water.

Launch virtual tour on context feature