The city has one of the oldest sewerage and stormwater drainage infrastructures in Australia. Traditionally, large pipes and channels remove excess stormwater from the city to minimise flooding risk and damage. But there’s a new kid on the block, working to slow down and filter pollution so it doesn’t harm our waterways.
Down the drain
Every year, nearly 3,000 tonnes of stormwater pollutants make their way into our waterways. That includes chemicals from car washing and oil from cars, leaves and garden clippings and plastic litter. It also captures cigarette butts, excess grease trap oil from restaurants, dog poo and overflows from the sewerage system.
This can lead to bacteria and viruses in our water, make waterways cloudy and suffocate fish, affect the health of birds and other animals and photosynthesis in plants.
But raingardens are a natural oasis protecting Sydney Harbour and Botany Bay from harmful pollutants.
A beautiful green garden with a big job
Raingardens are garden beds that slow and clean stormwater before it drains to our waterways. They’re usually found in street corners where cars can’t park. Raingardens have more grass-like shrubbery than usual roadside plantings. They’re set in lowered beds and over drain grills.
Raingardens use water-tolerant plants such as knotted club rush (Isolepis nodosa), basket grass (Lomandra longifolia), tropic belle (Lomandra hystrix) and native rosemary (Westringia fruiticosa). These plants have special filtering qualities.
The gardens are also planted with layers of materials including sandy soil and recycled crushed glass to filter rubbish and grab nutrients. Because the gardens are lowered and layered, they reduce the risk of flooding by slowing stormwater from entering the underground drainage system when there is a heavy rain. This also makes raingardens self-watering.
Where to spot them
If you’re walking around Camperdown, Chippendale, Darlinghurst, Erskineville, Glebe, or other areas in the inner city, keep an eye out. We have 154 raingardens so far and counting. We aim to reduce 50% of sediments and suspended solids and 15% of nutrients that flow into our waterways via stormwater runoff by 2030.