How do I build a raingarden?

Raingardens are easy to design and build and come in many different shapes and sizes. Here is a simple outline of what's involved in designing and building your own raingarden.

​Choose the right type of raingarden

Identify the location on your property where stormwater can be captured (for example, from a downpipe, near to a driveway, patio or overflow from a rainwater tank).

Then select a suitable raingarden design for the location you've chosen. There are many different raingarden types you can choose from.

Use one of our instruction sheets to help design, plan and build your raingarden.

Instruction sheets

Raingarden design

Start by either constructing your planter box or excavating your trench, depending on the type of raingarden you've decided to build.

A waterproof liner is sometimes used around the outside of raingardens when you need to prevent interaction with soils and groundwater to:

  • protect nearby buildings, foundations or infrastructure

  • avoid creating problems with saline groundwater or reactive clays

  • capture all stormwater for reuse

If you're building an inground style raingarden (including inground and infiltration raingarden or swale), dig the area with a gentle slope away from the house:

  • check the base of the raingarden is above the surrounding groundwater level

  • design your raingarden to treat stormwater runoff from gentle rainfall

  • runoff from heavy storms should bypass the raingarden into the drainage system

A saturated zone or submerged zone below the raingarden is recommended to provide water storage to help plants survive during dry periods and help remove nitrogen.

Note: a storage zone for water below the filter media can support plants during dry periods and improve treatment performance. This is especially useful in northern and western Melbourne where there's low rainfall. 

Raingarden plants

A wide range of plants are suitable for raingardens.

Be creative with your raingarden design using a variety of plants, rather than one species. This will prevent die-off and weeds. Mulch your raingarden with gravel to keep the moisture in. Avoid using bark or straw mulch as it'll float and wash back into the stormwater system.

Your local nursery can guide you on what plants are suitable for your area. When choosing plants for your raingarden make sure they're able to tolerate heavy rainfall as well as long dry periods. Native plants are usually more drought resistant and easier to maintain than introduced species.

Tips for a healthy raingarden

Raingardens are easy to maintain, especially when planted with native Australian plants. They don't need to be watered, mowed or fertilised. Follow these simple tips to make sure your raingarden functions well.

  1. Cover your raingarden with gravel mulch to retain moisture.

  2. Weed your raingarden until the plants have matured.

  3. Evenly distribute water flow into your raingarden to limit erosion from heavy rainfall. Strategically placed rocks may help with this.

  4. Inspect your raingarden - replace plants and repair erosion in your raingarden when necessary.

  5. Don't drive over or squash your raingarden as this will reduce its ability to work effectively.

If it doesn't rain, water your raingarden until your plants have established in compliance with your local water restrictions.

Need help building your raingarden

The easiest and cheapest way to build a raingarden is to do it yourself using our simple instruction sheets on this page.

The materials you need can be purchased from most hardware or garden supply stores. 

You could also contact an expert landscape gardener to help you build your raingarden and provide expert advice. A licensed plumber can help you with any modifications and diversions to your stormwater.

 

Last updated:
20 September 2017