What is A Soakwell?

In Queensland, heavy rainfall is nothing new. A summer storm can unleash a huge downpour in minutes, leaving backyards, driveways, and even house foundations under threat. When rainwater has nowhere to go, stormwater runoff can spread quickly, causing erosion, water pooling, and long-term damage to the surrounding area.

A soakwell system offers a simple yet effective way to tackle this. Installed underground, soakwells capture stormwater and gradually release it into the surrounding soil type, keeping water where it belongs—out of your living spaces and away from your neighbour’s property.

Soakwell installation has become a reliable choice across Queensland, especially in areas without extensive council stormwater infrastructure.

This article explains what a soakwell is, how it works, and why it’s a smart investment for protecting your property.

What Is a Soakwell and What Does It Do? 

A soakwell is an underground structure that collects and disperses stormwater on-site. During heavy rain, water runs through the gutter system and downpipes, then enters the soakwell. Perforations in the unit allow the water to slowly soak into the ground, preventing surface water issues.

1. Structure and Role in Drainage

Soakwells are usually:

• Cylindrical or cube-shaped units
• Built with openings that release water into surrounding soil
• Designed to keep water away from footings and landscaped areas

Their role is to:

• Effectively manage stormwater runoff
• Prevent soil erosion and flooding
• Stop water pooling near buildings, which can damage foundations

2. Difference from Pipes and Drains

• Stormwater pipes and kerb drains carry water off-site into council systems
• Soakwells keep the water within the property and return it to the soil naturally
• This approach is especially effective in sandy or porous soils, which absorb water quickly

3. Importance of Inspection

Regular inspection is important to keep the system working well. Checking gutters, downpipes, and the soakwell ensures it continues to perform during each storm and avoids unnecessary problems.

How Soakwells Work

A soakwell is designed to quietly manage excess water during rainfall. The process is simple yet effective:

• Rainwater flows off the roof into gutters
• Downpipes carry the water into underground stormwater pipes
• These pipes direct the flow into the soakwell

Once inside, the soakwell temporarily holds the water. Instead of rushing across the yard or spilling onto the street, the water stays contained for a short time.

Through small perforations, the soakwell then allows the stored water to:

• Slowly soak into the surrounding soil
• Mimic natural absorption
• Reduce surface runoff that causes flooding and pooling

The benefits go beyond the backyard. Soakwells help recharge groundwater levels and take pressure off council drainage systems.

Because the water is kept within property boundaries, a soakwell also satisfies legal requirements for on-site stormwater management.

Where Soakwells Are Commonly Used in Australia 

Soakwells can be found across the country, but their effectiveness depends heavily on soil type. In Queensland, they are widely used, especially where sandy or free-draining soils allow water to filter back into the ground efficiently.

Council requirements in many parts of QLD mandate on-site systems that manage stormwater runoff within property boundaries.

The primary function of a soakwell is to collect and disperse rainwater safely, which makes them a reliable choice in regions without extensive street drainage. They are particularly helpful in:

• Semi-rural areas with limited infrastructure
• Coastal properties with porous soil
• Off-grid homes where connecting to council drains isn’t possible

While less common in heavily urbanised areas with established stormwater networks, soakwells remain part of Australia’s broader shift toward water-sensitive urban design.

Common Types of Soakwells 

Soakwells come in several forms, each designed to handle rain water in different site conditions. Knowing the different types of soakwells helps in choosing the most effective soakwell for your property.

1. Precast Concrete Soakwells

• Reinforced and heavy-duty
• Trafficable when fitted with suitable lids
• Handle a large volume of water, ideal for driveways or big roof areas
• Often connected with piping to a soakwell from downpipes leading from gutters

2. Polypropylene Soakwells

• Lightweight and modular design
• Usually wrapped in geotextile fabric for protection
• Easy to install soakwells in tight or restricted spaces
• Strong enough to support driveways when installed properly

3. Legacy Options

• Include PVC drums, gravel pits, or brick-lined pits
• Found in older homes but rarely used in new builds
• Commonly replaced when people install a soakwell system that meets today’s standards

Sizing Soakwells Correctly

Choosing the right capacity is essential to avoid water damage and flooding during heavy rainfall. The number and size of soakwells required depend on the roof catchment area and any hard surfaces that direct water into the system.

A common guideline is:

• 1 m² of roof area requires 0.0125 m³ soakwell volume
• Example: a 200 m² roof will need about 2.5 m³ capacity, which can be achieved using soakwells placed around the property

Because soakwells range in size, some sites use one large unit while others rely on smaller soakwells connected. Plastic soakwells are popular where easy handling is important, while concrete units suit larger installations.

Soil type also plays a major role. In clay, overflow systems or alternatives may be necessary.

Always check local council standards when integrating soakwells and make sure you plan for maintaining soakwells in the long term.

How Soakwells Are Installed

Installing soakwells requires careful planning to make sure they work properly and stay safe for the long term.

The process generally follows these steps:

1. Planning: Work out how many soakwells you need, their size, and where to place them. Keep a safe distance from fences and building footings.
2. Excavation: Dig to the correct depth and width, usually about 1.5 times the soakwell’s diameter.
3. Base Preparation: Add a layer of compacted sand or gravel so the unit sits level and stable.
4. Unit Installation: Lower a precast concrete cylinder into the hole or assemble a polypropylene unit, then wrap with geotextile fabric.
5. Pipe Connections: Fit PVC stormwater pipes from downpipes with a steady slope and sealed joints.
6. Backfilling: Refill with compacted sand or gravel to hold the soakwell firmly in place.
7. Surface Restoration: Finish with soil, turf, or paving, making sure water drains toward the unit.

Don’t Example: Don’t install a soakwell too close to your home’s footings. It can destabilise the ground and lead to structural issues.

Local Regulations and Council Requirements

In Queensland, stormwater management is guided by both the National Construction Code and local council rules. The Code requires that stormwater is controlled on-site and must not damage neighbouring properties.

In Brisbane, new builds and major renovations usually need an approved drainage plan before permits are issued. This often includes details on soakwell sizing, setback distances, and overflow design.

Across the eastern states, the preference is to connect downpipes to council stormwater pipes. However, soakwells may still be approved where soil conditions allow for proper infiltration.

Councils may also require:

• Trafficable lids for areas used by vehicles
• Minimum trenching depths for pipes
• Overflow connections for extreme rainfall events

All installations must meet AS/NZS 3500.3 Stormwater Drainage Standards. Following these ensures soakwells are safe, compliant, and effective under local site conditions.

When Soakwells May Not Be Suitable

1. Clay or Poorly Draining Soils

Soakwells struggle in heavy clay or areas with poor soil permeability. Water cannot filter away quickly, leaving the system ineffective.

2. High Water Tables

Properties with a high water table may find soakwells unsuitable, as stored water has nowhere to drain.

3. Limited Space

Sites lacking enough setback from footings or boundaries cannot provide the safe clearance needed for soakage.

4. Alternative Solutions

In these cases, engineered systems such as detention tanks or French drains are often recommended. A soil percolation test or geotechnical assessment should always be carried out before deciding.

Why Soakwells Are a Smart Long-Term Solution

Soakwells contribute to protecting homes and landscapes in more ways than one. When soakwells are mostly connected to the gutters of a building, they manage stormwater directly at the source. Their benefits include:

• Preventing costly flood damage and soil issues
• Supporting sustainable water practices, as soakwells help recharge groundwater
• Reducing reliance on already overloaded council stormwater networks
• Adding property value through compliance and practical design
• Offering flexibility, since soakwells come in a variety of sizes to suit different sites
• Being cost-effective when included during the construction of a new house

Take Control of Stormwater, the Smart Way

From protecting your home’s foundations to supporting eco-conscious drainage design, soakwells are an essential addition to many properties in Queensland.

Building a new home or upgrading an older system both present the perfect opportunity to invest in proper stormwater management.

Making this choice is one of the smartest moves a homeowner can take to safeguard property and prevent future drainage problems.

Need help managing your stormwater safely and legally? All Kind Wastewater offers expert solutions for sewage and stormwater systems. Reach out today to see how our services can keep your property safe and compliant.

FAQs About Soakwells in Australia 

1: Do all homes in Australia need soakwells?

No, but many WA homes require them. In other states, usage depends on council rules and soil conditions.

2: Can soakwells be installed under driveways?

Yes, if fitted with a traffic-rated lid and designed for load-bearing.

3: How deep should a soakwell be buried?

Typically, the top is 300–500 mm below ground level, deeper for vehicle areas.

4: Do soakwells work in clay soil?

Not effectively. Alternative solutions like detention systems or trench drains are better suited for clay-heavy sites.

5: How do I calculate how many soakwells I need?

Multiply the roof area (in m²) by 0.0125 to get the required soakwell volume in m³.