Managed properly, stormwater is a valuable resource that can enhance cities' liveability, sustainability and resilience. We do it by working with local government authorities (LGAs) to improve the health of our waterways, provide opportunities for stormwater reuse and protect people and properties from flooding. So how do we manage stormwater, and how do we redirect it?
Urban environments are packed with hard surfaces such as roofs, roads and footpaths that prevent rain from soaking into the ground. Stormwater is the water that flows on those surfaces after rain. Often it flows from property drains to street gutters operated by local councils, and these may connect to our large channels, pipes and creeks. This is what forms the stormwater drainage system.
Our stormwater network provides services to about 634,530 properties. It consists of:
Only authorised maintenance crews can safely enter our stormwater system, which includes open channels, drains and underground tunnels. These are dangerous because:
Heavy or prolonged rain can cause creeks and coastal rivers to rise quickly. It can take only minutes for waterways to pose a major flood hazard. Fast-moving floodwaters in populated areas are a serious risk to life and property.
Flash floods are the most dangerous type of flood, and result from short, extremely intense bursts of rain. They often occur in heavily populated areas with little or no warning. In contrast, rivers in western NSW generally flood slowly, usually taking weeks and months to fully develop. This can lead to major property damage and isolation of entire communities. Floods are Australia’s most costly and predictable natural disaster.
This difference in speed and duration of flooding is caused by:
We help prevent flooding in many ways.
Our stormwater assets are located across 23 LGAs in Greater Sydney, and we work closely with these LGAs to reduce the impact of flooding on the community. We also offer our expertise in stormwater catchments outside our areas of responsibility.
We protect our stormwater assets so they work as intended. We regularly check the structure and operation of our assets and maintain or renew them. This is a key part of how we manage flooding.
Sydney Water assesses all development applications near our stormwater assets. Sometimes proposed developments can be impacted by flooding or make flood risk worse for others. If this happens, the developer needs to propose alternative designs and consult with LGAs and Sydney Water.
We participate in Floodplain Risk Management Committees with local councils, communities and other agencies, outlined in the NSW Government. These committees oversee the preparation of:
We play an active role in the stormwater industry, and participate in many council and community events to address flooding. We contribute by sharing our knowledge, offering advice and discussing proposed modifications to the stormwater system.
Stormwater can carry pollution like litter, sediment, grease, oil and metals that are picked up from roads and properties. This pollution affects the quality of our local waterways. We've installed over 70 stormwater quality improvement devices (SQIDs) to help clean stormwater. These include trash racks, sediment traps and litter booms.
If you're connecting to our stormwater pipes or developing your property, you must meet our stormwater quality targets.
Stormwater harvesting is the practice of collecting, storing and treating stormwater from urban areas. It's collected from stormwater drains or creeks, rather than roofs, and treated so it’s safe to use as recycled water. Then, it's commonly used to water public parks, gardens, sports fields and golf courses.
Benefits of stormwater harvesting are that it:
We work with local councils and other agencies to manage stormwater and investigate opportunities for stormwater's collection and reuse. It's one of the many ways the NSW Government is securing Sydney’s water supply for a growing population.
There's a lot of advice and assistance available if you want to set up your stormwater harvesting scheme from our stormwater system. Find out more about what you need to do from our fact sheet,. You can also review our .