Protecting waterways from pollutants

Small, green gardens are popping up all around Sydney and play a vital role in keeping waterways free from harmful pollutants.

These are Sydney’s raingardens and 118 of them have now been installed to treat stormwater, protect local waterways and green inner-city streets. The City of Sydney is committed to maintaining high water quality and reducing stormwater pollution discharging into Sydney Harbour and Botany Bay.

Every year nearly 3,000 tonnes of stormwater pollutants make their way into our waterways, damaging our environment.

These beautiful green gardens play a very important role. The City now has over 2,300 square metres of raingardens that filter out pollution and contribute towards our targets to reduce sediment reaching our waterways by 50% by 2030.

The raingardens are one of many water related projects being delivered by the City in streets, parks, ovals and community centres. These initiatives replace mains water use with alternative sources and reduce discharge to the ocean.

The self-watering gardens are installed often when new traffic public works improvements are made to the City’s streets. They are typically at street corners in the space where cars cannot park, and they replace what was once asphalt road pavement.  By positioning them at such locations, the City also improves pedestrian safety by reducing the road crossing distance.

The raingardens include water-tolerant plants such as:

  • Knotted club rush (Isolepis nodosa)
  • Basket grass (Lomandra longifolia)
  • Tropic belle (Lomandra hystrix)
  • Blady grass (Imperata cylindrical)
  • Longhair plumegrass (Dichelachne micrantha)
  • Swamp banksia (Banksia robur)
  • Gymea lily (Doryanthes excels)
  • Thyme honey-myrtle (Melaleuca thymifolia)
  • Lilly pilly (Acmena smithii)
  • White correa (Correa alba)
  • Bottlebrush (Callistemon)
  • Blue flax-lily (Dianella caerulea ‘King Alfred’)
  • Native rosemary (Westringia fruiticosa).

The plants are chosen for their ability to flourish in wet growing conditions and for their filtering qualities to clean stormwater before it runs into waterways, removing damaging elements such as chemicals, rubbish and oils.

Stormwater runs into the gardens from hard surfaces such as streets and nearby roofs whenever it rains. Layers of select materials such as sandy soil and recycled crushed glass filter the water and allow the plants to grow and absorb the nutrients in the water. Raingardens are a way to maintain, help green the City’s streets and bring a welcome splash of nature into our streets.

How a raingarden works

A diagram that illustrates how pollutants absorbed by rainwater on roads and footpaths are filtered out by adjacent raingardens before flowing into Sydney Harbour and Cooks River.
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Raingardens: Natural water filters PDF 2.5 MB Download

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Last updated: Friday, 8 April 2016