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Water sources
Our main water sources
Greater Sydney’s water supply comes from dams, rivers and oceans. These sources are part of the broader natural water cycle, where water moves through the environment before being managed to ensure a safe and reliable supply. This process is known as the urban water cycle, helps deliver clean water to homes and businesses.
Dams and rivers
Rain falling in river catchments is Sydney’s main source of drinking water and contributes 85% of our drinking water supply. Dams are built across rivers to capture and store this water. The stored water, often called a storage reservoir, is managed by WaterNSW, who oversees five catchments supplying 11 major dams for Greater Sydney.
Warragamba Dam
Sydney’s dam water is filtered at one of our 9 water filtration plants to ensure it is clean, safe and high quality. Warragamba Dam, Sydney’s largest, supplies about 80% of Greater Sydney’s water. It collects water from the Wollondilly and Coxs river systems, forming Lake Burragorang behind its dam wall. Additional water comes from smaller dams to the south of Sydney and in the Blue Mountains, including Cataract, Cordeaux, Avon and Nepean dams.
Visit WaterNSW to check dam levels or check on rainfall and dam levels in the Greater Sydney Catchment.
When Warragamba is full, it holds four times more water than Sydney Harbour.
Oceans - desalination
Oceans can be used as a drinking water source, offering a reliable supply unaffected by changing rainfall. Desalination removes salt from seawater to produce fresh water, helping meet demand in areas with limited river access, drought conditions or growing populations.
Sydney Desalination Plant at Kurnell, between Botany Bay and the Tasman Sea, can produce up to 250 million litres of drinking water a day—around 15% of Greater Sydney’s supply. Its capacity can be adjusted based on demand, providing a rainfall-independent water source.
The Sydney Desalination Plant requires roughly 38 megawatts at full production and is 100 per cent powered by renewable energy.
Diversifying our water supply
Expanding and diversifying our water sources is essential to support a growing population and adapt to climate change. By 2050, we aim for 65% of Sydney’s drinking water to be independent of rainfall.
A key part of this strategy is purified recycled water (PRW)—water from homes and industries that is treated to meet the strict Australian Drinking Water Guidelines. Incorporating PRW into the water supply will help build a more resilient system, ensuring a sustainable and drought-proof water source for future generations.
People have been safely drinking purified recycled water for over 50 years in more than 35 cities, including parts of California, Singapore and Perth.
Catchments
A catchment is an area of land where rainfall collects and flows to a common point, such as a river, lake or ocean. Rainwater moves downhill by gravity as surface water or seeps into the ground to become groundwater, which feeds into waterways and water bodies.
The Hawkesbury-Nepean River system, covering over 22,000 square kilometres, is Sydney’s largest drinking water source. Land use in a catchment affects water quality and availability, making careful management essential. WaterNSW protects these catchments to ensure a reliable supply of fresh water for Sydney, the Illawarra and the Blue Mountains.
Other sources
To secure Sydney’s water future, we are expanding alternative water sources, including recycled water, groundwater and rainwater tanks.
Recycled Water
Recycled water is treated wastewater or stormwater that can be safely returned to homes and businesses. In Greater Sydney, it is used for irrigation, toilet flushing, firefighting, manufacturing, cooling urban spaces and many more things.
We expect to use more recycled water in the future. Learn more about water recycling in Greater Sydney.
Recycled water is high quality.
Groundwater
Groundwater is water stored beneath the Earth’s surface in aquifers. It naturally replenishes rivers, streams and wetlands and can be accessed through wells and bores. When managed sustainably, groundwater is a valuable water source, especially in drier areas.
Learn more about groundwater use from NSW Health.
Rainwater tanks
Rainwater tanks capture water for household use, such as watering gardens, flushing toilets and washing clothes. However, in urban areas, rainwater is generally not safe for drinking due to potential pollution. NSW Health recommends using the public water supply for drinking and cooking.
Learn more about rainwater tanks from NSW Health.
Rainwater tanks collect water that you can use in your garden.
