When it rains in urban areas, water runs off hard surfaces like roofs, roads, car parks, paths and driveways into stormwater drains. 

This stormwater then flows into:

  • creeks
  • the harbour
  • the ocean.

Watch our video to find out more about Sydney's stormwater network.

Stormwater flows into small drains which lead to larger stormwater drains and eventually join large (trunk) drains or pipes that carry the water to creeks, rivers and the ocean. Find out more about our stormwater network.

Every year, about 500 billion litres of stormwater flow to the ocean. That’s about as much water as in Sydney Harbour!

Stormwater Quality Improvement Devices

Stormwater Quality Improvement Devices (SQIDs) collect rubbish and some other pollutants from waterways.

Stormwater often carries nutrients (fertilisers), oil, grease, sediment, litter and animal droppings.

Unlike wastewater, stormwater isn't treated before entering directly into creeks, rivers and oceans.

We (and many councils) manage stormwater using Stormwater Quality Improvement Devices (SQIDS). 
Litter traps are one of the types of devices we use along with constructed wetlands and sedimentation basins. This helps improve the quality of stormwater and reduces pollutants entering the waterway. 

In the past 20 years, we've installed 70 SQIDs. These devices have helped remove over 35,000 cubic metres of litter and organic waste as well as 39,000 tonnes of sediment from stormwater before it reaches Sydney’s natural waterways.

You can help us keep our waterways clean by:

  • putting rubbish in the bin
  • washing cars on the grass instead of hard surfaces so detergents wash into the soil rather than stormwater drains
  • sweeping leaves, dirt and rubbish away from gutters
  • making sure your gardens have good borders so soil doesn’t wash away
  • putting grass clippings in the compost bin or on the garden
  • picking up your pet’s droppings and putting them in a bin
  • asking your local council how to safely dispose of chemicals, pesticides, paints and oils, as these should never go down the drain.
Stormwater wetlands

Wetlands are built to collect and clean stormwater.

Collecting, cleaning and re-using stormwater is called stormwater harvesting.

Stormwater harvesting can help reduce litter and pollutants in natural waterways and may reduce demands on drinking water.

There are two main ways that stormwater is being managed in Sydney:

Water sensitive urban design (WSUD) uses urban design principles and processes to sustainably manage the total water cycle at a local level.

Many councils are implementing water sensitive urban design projects to manage increased volume and poor quality stormwater that goes into local waterways.

Stormwater harvesting is usually a key element of WSUD to:

  • overcome water shortages
  • reduce urban temperatures
  • improve the health of waterways and the landscape of cities.

Stormwater harvesting
projects collect and clean stormwater and use this water for non-drinking purposes.

WSUD using stormwater harvesting can help reduce demand on drinking water supplies by providing another water source for activities like:

  • watering sports fields and gardens
  • flushing toilets
  • hosing down outdoor public spaces. These activities don't really require water treated to a drinking water standard.

Finding practical and cost effective stormwater harvesting options is a challenge. Some of the problems are:

  • finding suitable space to build large storage and treatment facilities
  • treating the stormwater so it's good quality and doesn't harm the environment
  • finding efficient ways to re-use the water, including transporting the treated stormwater to where it's needed
  • making sure stormwater harvesting doesn't damage waterways by reducing natural flows.
Stormwater culvert

Stormwater drains are dangerous.

Stormwater drains can be very dangerous places.
It's important that you don't go into drains - even during fine weather. This is why stormwater drains are often fenced and have warning signs telling people to stay out. It's also a good idea to keep pets away from drains.

Stormwater drains can be open channels or underground tunnels. They are dangerous because:

  • water in drains can rise quickly and unexpectedly, even when it's not raining in the local area
  • when it rains, huge amounts of water can suddenly wash into the drain
  • if you're swept away by water in a stormwater drain, you may not be able to get out and could even drown. Even shallow water can be very powerful and could knock you over
  • drains can contain pollution like broken glass, dangerous chemicals and disease causing bacteria.

Don’t try to lift stormwater grates near footpaths and roads, even if something has accidentally dropped down. These grates can be very heavy.

If you're in a flooded area, stay away from roads, footpaths and areas where you can’t clearly see where you're walking.

Many schools have large areas of hard surfaces like car parks, basketball courts, assembly areas or concrete quadrangles.

These hard surfaces increase the amount of run-off after rain. This run-off, called stormwater, can carry dirt and rubbish with it to the nearest school stormwater drain. These drains form part of a local stormwater network, which lead to the nearest waterway.

By doing a stormwater audit, you can:

  • find your school’s stormwater drains
  • see how polluted they are
  • work out why they might be polluted
  • create a Stormwater Management Plan to reduce pollution in the drains.

By taking the actions identified in your stormwater audit, you can help reduce pollution in local waterways.

Download our Stormwater Audit fact sheet to find out how to audit your school's stormwater drains.