When heavy rain hits, stormwater can quickly overwhelm drainage systems—especially in built-up areas with lots of hard surfaces like concrete driveways, patios, and roofs. A soakaway is a simple and environmentally friendly way to manage stormwater on your own property. It collects runoff from roofs and paved areas and allows it to slowly soak into the ground instead of flowing into the street or stormwater drains. Here’s a detailed guide to what a soakaway is, how it works, and how to make sure it performs effectively on your property.

What Is a Soakaway?

A soakaway is essentially an underground pit or chamber designed to temporarily store rainwater and let it gradually infiltrate into the surrounding soil. It acts as a buffer, reducing the amount of water entering the stormwater system and helping to prevent local flooding.

Traditionally, soakaways were filled with rubble or gravel, but modern systems often use modular plastic crates with a high void ratio. These are lightweight, easy to install, and can be configured to suit different site conditions and roof sizes.

The soakaway is usually installed in the garden or yard, connected to downpipes or surface drains via underground pipes. When it rains, water flows into the soakaway, where it’s held temporarily before seeping into the soil.

Why Install a Soakaway?

There are several benefits to having a soakaway on your property:

• Reduce pressure on stormwater systems – by managing runoff locally, you help prevent street flooding and erosion.
• Environmentally sustainable – water returns to the natural groundwater system instead of being lost through storm drains.
• Protect your home – a well-placed soakaway helps divert water away from your house foundations, reducing the risk of dampness and structural damage.
• Comply with local regulations – in many Australian councils, property owners are encouraged or required to manage stormwater on-site, especially in new developments or renovations.

How Soakaways Work

When rainwater enters the soakaway, it fills the voids within the structure. From there, it seeps out through the sides and base into the surrounding soil. The rate of infiltration depends on the soil type—sandy soils drain quickly, while clay soils drain slowly and may require a larger soakaway or additional drainage solutions.

To keep the system working efficiently, it’s essential to install a silt trap or leaf filter before the soakaway. This prevents debris, leaves, and sediment from clogging the system.

A properly sized soakaway can handle even heavy downpours, but it must be designed according to the roof area, local rainfall intensity, and soil permeability.

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How to Install a Soakaway

You can hire a licensed plumber or drainage contractor to install a soakaway, but smaller systems can sometimes be installed by experienced homeowners. Here are the key steps:

1. Test the soil’s infiltration rate. Dig a small test pit, fill it with water, and measure how long it takes to drain. This helps determine the required soakaway size.
2. Choose the right location. The soakaway should be at least 3–5 metres from your house and 1–2 metres from property boundaries. Avoid areas with high groundwater or poor drainage.
3. Excavate the pit. The size depends on your roof area and soil type.
4. Line the pit with geotextile fabric. This prevents soil from entering the soakaway while allowing water to pass through.
5. Install the soakaway crates or gravel. Connect them to your downpipe or stormwater drain using PVC pipes.
6. Backfill and cover. Wrap the top with geotextile, then backfill with soil and finish with turf or paving.

Before starting, check with your local council or water authority—some areas require approval or have specific design standards for on-site stormwater management.

Maintenance and Lifespan

A soakaway requires minimal maintenance, but it’s important to clean the silt trap or leaf filter regularly—usually once or twice a year. If these become blocked, water can back up and reduce the soakaway’s effectiveness.

Modern soakaway crates can last 30–50 years if properly installed and protected from sediment build-up. After heavy rain, check that water drains away as expected. Standing water or slow drainage may indicate clogging or poor soil infiltration.

A Smart Investment for a Changing Climate

With more frequent intense rainfall events across Australia, managing stormwater on-site is becoming increasingly important. A soakaway is a practical, low-impact way to protect your property, reduce strain on public drainage systems, and support a more sustainable water cycle.

It’s an investment that pays off over time—less risk of flooding, better protection for your home, and a contribution to a more resilient environment.