Desalination

Part of our resilient water supply

Desalinated water from the Sydney Desalination Plant is an important part of how we’ll continue to provide secure, reliable drinking water when drought, bushfires and floods impact our dams.

The Sydney Desalination Plant is operating
It's helping to reduce pressure on our water filtration plants and network, enabling us to respond to Greater Sydney's water demand.

Reliable water, whatever the weather

Desalinated water and you

From seawater to drinking water

Environmental impact

Reliable water, whatever the weather

The privately owned Sydney Desalination Plant at Kurnell is part of the NSW Government's plan to ensure a secure and affordable water supply system for Greater Sydney. Most states have at least one large desalination plant.

Desalinated water is a rainfall-independent water supply that helps us respond to increasing demand for high-quality drinking water. While the Plant is operating, we can adjust the capacity based on our system's needs.

The Sydney Desalination Plant at Kurnell.

Desalinated water and you

The Sydney Desalination Plant feeds into the Potts Hill delivery system, which supplies water to about 1.5 million people across Sydney. Locations include the Sydney CBD, the Inner West and Eastern Suburbs, southern Sydney, parts of the Sutherland Shire and, at times, as far west as Auburn. If you live or work in an area supplied with water from the Plant, you may receive water from dams, the Sydney Desalination Plant, or a combination of both.

All drinking water the Plant produces meets the Australian Drinking Water Guidelines. Find out about the quality of the water we supply to your property in our daily drinking water quality report.

Council areas that receive water from Sydney Desalination Plant as part of their water supply.

The cost of running the Plant

Running the Sydney Desalination Plant for the 12 months up to March 2025 cost the average household $22.04 a year. This was reflected in our 2024–25 water service charges. Prices are regulated by the Independent Pricing and Regulatory Tribunal (IPART).

From seawater to drinking water

The Sydney Desalination Plant has the capacity to provide up to 15% of Greater Sydney's drinking water, and can produce an average of 250 million litres of drinking water each day.

Seawater is turned into clean and safe drinking water using a 6-step desalination process:

  1. Seawater intake and screening
    Seawater is drawn from the Tasman Sea through intake pipes. It comes from about 300 metres offshore and 25 metres below the surface.
  2. Pretreatment filtration
    Once the water arrives at the Plant, it's filtered to remove any solid material, such as algae and small dirt particles.
  3. Reverse osmosis
    The filtered seawater is then pumped at a very high pressure through the reverse osmosis membrane system, which removes salt and other minerals.
  4. Post treatment
    The water produced by the reverse osmosis process requires minerals to be added before it's fluoridated and chlorinated, in line with Australian Drinking Water Guidelines and NSW Health requirements.
  5. Drinking water delivered to our supply network
    After treatment, desalinated water is pumped directly to the existing water distribution network. It flows through an 18-kilometre pipeline passing under Botany Bay to our supply network at Erskineville.
  6. Seawater concentrate outlet
    Seawater concentrate (left over from the desalination process) is sent back to the ocean via an outlet tunnel and specially designed dispersion nozzles. These nozzles make sure the water mixes rapidly and returns to normal seawater salinity and temperature so it doesn't have any adverse effect on the local marine environment.

Environmental impact

  • The Sydney Desalination Plant is powered by 100% renewable energy.
  • One third of the site at Kurnell is a conservation area where native species of flora and fauna are regularly monitored.
  • The conservation area is protected and closely monitored, with programs to survey the number of grey-headed flying foxes, and green and golden bell frogs. Bush regeneration and removal of invasive flora from the conservation area is carried out on an ongoing basis to ensure the animals have a safe place to feed, breed and roost.
  • Marine life can swim out of the seawater intake tunnel and not get drawn into the Plant.
  • The Plant is proud to be part of a program that provides eucalyptus leaves to feed a colony of orphaned and rescued koalas at Symbio Wildlife Park in nearby Helensburgh. As part of the program, about 800 eucalyptus trees were planted in an unused area of the site.

Find out more about the Sydney Desalination Plant's strong commitment to minimising its environmental footprint.

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