We protect our assets so they work as intended and have capacity for some stormwater during a flood. We check the structure and operation of our assets regularly, and maintain or renew them.
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Rain's too valuable to go down the drain
Stormwater is a valuable resource that enhances Greater Sydney's liveability, sustainability and resilience. We aim to improve waterway health, provide opportunities to reuse stormwater, and protect people and properties from flooding.
Our stormwater systems
In urban environments, hard surfaces like roofs, roads and footpaths prevent rain from soaking into the ground. This creates stormwater, which often flows from property drains to street gutters operated by local councils. Gutters may connect to large channels, pipes and creeks. These form our stormwater drainage systems.
Our stormwater systems provide services to about 645,000 properties in Greater Sydney. They consist of:
- 73 catchments
- 458 kilometres of channels and pipes
- over 80 stormwater quality improvement devices.
We work with local councils and other agencies to manage Sydney's stormwater. We also investigate opportunities to collect and reuse stormwater through stormwater harvesting.
Stay safe around stormwater
Stormwater systems include open channels, drains, tunnels and maintenance holes. They can be dangerous. Only authorised maintenance crews can enter them safely.
- Water can rise fast and unexpectedly, even if it's not raining.
- Shallow flowing water can be powerful enough to knock you over.
- Stormwater may contain dangerous chemicals, disease-causing bacteria and other pollutants.
How we help prevent flooding
Stormwater in channels, creeks, and coastal rivers can rise quickly during heavy or prolonged rain. Waterways can pose a major flood hazard in minutes. In populated areas, fast-moving floodwaters are a serious risk to life and property. Floods are Australia's most costly and predictable natural disaster.
How quickly floods happen and how long they last depends on soil type, storm length and intensity, topography (landscape), land use and development. Hard surfaces in urban areas make rainwater run-off faster.
We help prevent flooding in many ways.
Proposed developments may be impacted by flooding or make flood risk worse for others. If this is the case, the developer must propose alternative designs and consult with councils and Sydney Water. We assess all development applications near our stormwater assets.
Local councils have primary responsibility for flood planning. They organise Flood Risk Management Committees to follow the process in the NSW Government Flood risk management manual. Committees include agency and community representatives, and oversee preparation of flood risk management studies and plans. We participate where we have stormwater assets.
We also join council and community events to address flooding. We share knowledge, offer advice and discuss proposed modifications to the stormwater system. If a flood risk management plan recommends changes to our stormwater assets, we work with councils to develop ideas and implement works where they’ll make a difference.
How we improve waterway health
Stormwater washes litter, sediment, grease, oil and metals from roads and properties and carries them into our waterways. This affects the health of our creeks, rivers, harbour and beaches.
Keeping pollutants out of major waterways
We've installed over 80 stormwater quality improvement devices (SQIDs) to help clean stormwater before it reaches major waterways. SQIDs include trash racks, gross pollutant traps and floating litter traps, which are also known as litter booms.
We're integrating water sensitive urban design (WSUD) into parks and other areas around Sydney. WSUD includes natural, planted vegetation areas that filter stormwater through physical and biological processes.
Healthier waterways create new habitats for wildlife and revitalised spaces for the community to enjoy. Visit Sydney Water Talk to keep track of our waterway health improvement projects.
Floating litter trap on Cooks River at Boat Harbour, Hurlstone Park.
Naturalising and replacing channels
We work with local councils and state government agencies to manage the stormwater system and improve our large stormwater channels and drains. Sometimes, we naturalise channels if they need to be replaced or rehabilitated by replacing steep concrete channel walls with gentle slopes stabilised by rock and native plants. Naturalisation boosts habitat for native animals, urban greening and cooling, public spaces, and longevity for channels.
Visit Sydney Water Talk to learn about channel naturalisation projects like Muddy Creek, Johnstons Creek and Powells Creek.
Naturalisation transforms degraded channels into living waterways.
Maintaining Caddies Creek catchment
Caddies Creek catchment is flood-affected trunk drainage land that we own around Caddies Creek and Second Ponds Creek (the Rouse Hill Development Area). Trunk drainage land typically includes creeks, bushland, or parks and reserves with stormwater pits or small concrete channels in the middle.
The land isn't developed for housing. It's reserved to help manage stormwater from large storms and help prevent flooding. It also creates habitat for native plants and animals. In this trunk drainage land we:
- plant local native species
- remove weeds and invasive species
- remove rubbish and sediment.
Restoring local creeks and waterways improves the quality of water going into the Hawkesbury-Nepean River.
A view across Caddies Creek catchment in Rouse Hill.
Caring for Botany Wetlands
We own the Botany Wetlands, the largest coastal freshwater wetlands in Sydney. They cover a 4.5-kilometre corridor in Sydney's east, and we lease most of the surrounding area to golf clubs. The wetlands have significant ecological and heritage value. They also provide important recreational, educational and scientific value to the community.
Our Plan of Management for Botany Wetlands 2018–2028 shows how we manage and protect the wetlands' value. To learn more, please email propertyenvironmental@sydneywater.com.au.
Our stormwater programs improve the health of Botany Wetlands.