It’s estimated that the equivalent of six Sydney Harbou’s worth of storm water runoff is produced in Australia’s urban areas each year, and there are ways of capturing and utilising rain water before it gets lost in storm water drains, and adds to pollution in water ways.
“A significant amount of precious storm water is lost to us and adds pollution to our waterways as unfiltered rain runs straight into rivers and oceans,” says co-founder and creative director of Landart Landscapes, Matt Leacy.
“Creating a rain garden or storm water-smart garden is something property owners can do to make good use of rainfall,” says Matt.
“Rain gardens are self-watering, low maintenance, and help to reduce use of water in the garden, as well as filtering and purifying water so that it is then safe to be reused.”
“Rain gardens can be created in a variety of ways. Research and consultation with a landscape designer on what will work best for a particular space is always advisable,” says Matt. “Different options for creating a rain garden include downpipe diversion, a green roof, in-ground, planter box, tank diversion, swale and a vegetable rain garden.”
How to create a rain garden, according to Matt
- Choose where you’re going to capture the bulk of your storm water, such as a downpipe, driveway or pathway, or from a rainwater tank
- Choose a planter box that fits your space, or excavate a trench that leads water to a lower lying point in your garden.
- You will need to layer your planter box with gravel, soil and sand, and then a bottom layer of gravel to aid with water filtration, and to allow the water to drain freely at the base into an exit pipe
- Make sure you have a waterproof liner for your planter box to ensure the storm water is captured for reuse.
- If you’re creating an in-ground rain garden, dig the area with a gentle slope away from the house. You will also need to dig a shallow trench that re-directs water to this part of your garden where it can be captured and released, ready to be absorbed and filtered by plants and engineered soil. You will also probably need to plumb in pipes
- Speak to your local nursery to check the best plants to use in your rain garden. Some good options include kangaroo paws, native grasses, native rushes and Dianella. The main thing is to ensure that whatever you choose is both drought-tolerant and able to withstand heavy rain and water. Native plants tend to be lower maintenance and more suitable than introduced species.
- Cover your rain garden with mulch to retain moisture, such as gravel. Avoid bark or straw as these float into storm water drains
Rooftop options
“Working with a landscape designer will allow you to further maximise the land on your property for rain gardens, whether that’s via a rooftop garden or a more complex built-in in-ground system,” says Matt.
“Rooftop gardens require a structural engineer to check the roof is properly intact and suitable for the type of rain garden you’re planning to do, and some in-ground systems require plumbing – all of which a great landscape designer should be able to manage for you.”
“By implementing storm water-smart landscaping solutions in urban areas, we can all help to reduce our water usage, as well as lessening the impact of storm water run-off on our waterways.
Care tips from Matt
- While rain gardens are very low maintenance, you will need to weed until the plants have matured. You will also need to monitor your rain garden in the first heavy downpours to ensure the water is evenly distributed. You may also need to also add plants or some rocks to help control erosion.
- If it doesn’t rain when you’re first setting up your rain garden, you will need to water your plants until they’re established. Be sure to do so in compliance with local water restrictions.
