What is a Soakaway? Complete Guide to How It Works and When You Need One
If you have ever wondered “what is a soakaway?”, you are not alone. Many homeowners and property developers encounter the term during building projects or when dealing with drainage issues. In simple terms, a soakaway is an underground system that collects rainwater and slowly releases it into the surrounding soil. Instead of sending surface water into public drains, it allows water to soak naturally back into the ground.
This method reduces flooding risks, prevents damage to buildings, and supports the environment. At Drainage and Plumbing LTD, we install, maintain, and repair soakaways for properties across South East England, including Croydon, Sutton, Banstead, Bromley, Epsom, Reigate, Crawley, and many more towns.
Because urban areas have more hard surfaces than ever before, the role of soakaways has become more important. They are one of the most practical and eco-friendly ways to handle excess rainwater, especially when public drains cannot cope with heavy rainfall.
Understanding the Purpose of a Soakaway
A soakaway’s main purpose is to manage surface water effectively. Cities and towns have driveways, pavements, and roofs that do not absorb water. As a result, rainwater quickly builds up and can cause standing water or local flooding.
By storing and gradually releasing water into the soil, a soakaway mimics the natural drainage cycle. It takes the pressure off public drainage systems, which are often at risk of overflowing during storms. In addition, it helps maintain a healthy water balance in the environment.
How Does a Soakaway Work?
Although the idea is simple, the way a soakaway works involves several key steps that make it efficient.
1. Collection of Water
Rainwater from roofs, patios, driveways, and other hard surfaces flows into gutters and downpipes. From there, underground pipes direct the water to the soakaway location.
2. Removal of Debris
In many designs, a silt trap or small catchment chamber is installed before the soakaway. This prevents leaves, soil, and other debris from entering and clogging the system. As a result, the soakaway stays functional for many years.
3. Storage in the Chamber
The water then enters a specially designed chamber, and from this point, the process becomes highly efficient. In traditional soakaways, this chamber is often filled with clean, angular gravel or rubble, which allows water to pass through easily. However, in modern systems, engineers frequently use high void plastic soakaway crates instead, because they can store a much larger volume of water within a smaller space, and therefore improve both performance and durability.
4. Filtration Through a Geotextile Membrane
The chamber is wrapped in a geotextile membrane, which allows water to pass through while keeping soil particles out. This protects the structure and ensures water can always flow freely.
5. Gradual Percolation into the Soil
Water seeps out through the sides and base of the soakaway into the surrounding soil. The speed of this process, called percolation, depends on soil type. Sandy soil drains quickly, while clay soil slows the process.
6. Step-by-Step Guide to Installing a Soakaway Drainage System
Finally, the stored water disperses fully into the ground, leaving the soakaway ready for the next rainfall.
When Might You Need a Soakaway?
There are several situations where a soakaway is the most suitable drainage solution.
New Property Developments
Building regulations in many areas of South East England require new properties to manage rainwater on-site. A soakaway is often the preferred choice because it is cost-effective and environmentally friendly.
Property Extensions
Adding a large extension, garage, or driveway increases the amount of rainwater runoff. In such cases, a soakaway helps manage the extra water without overloading drains.
Persistent Garden Flooding
If water remains in your garden for several days after rain, your property likely needs better drainage. A soakaway can absorb excess water and prevent waterlogging.
Replacing Inefficient Drainage Systems
Older drainage systems may no longer work effectively. Installing a modern soakaway can restore proper water management and reduce maintenance issues.
Rural and Remote Properties
Homes far from public surface water drains often rely on soakaways as the only practical way to manage rainwater.
Benefits of Installing a Soakaway
A soakaway offers multiple long-term benefits for both your property and the environment.
Reduces Flooding Risk
By handling rainwater on-site, soakaways reduce the amount of water entering public drains. This lowers the chance of local flooding during storms.
Environmentally Responsible
Soakaways recharge groundwater levels and support the natural water cycle. They are a key element of sustainable drainage systems (SuDS).
Protects Property Foundations
By directing water away from your home, a soakaway reduces the risk of dampness and structural damage.
Cost-Effective Maintenance
Once installed, a soakaway needs very little upkeep. In the long term, it can save you money on repairs and prevent costly flood damage.
Improves Landscaping
In addition, preventing waterlogging keeps lawns and plants healthy, and as a result, it makes your garden look more attractive and vibrant throughout the entire year.
Types of Soakaways
Not all soakaways are the same. Choosing the right type depends on your property’s needs.
Traditional Gravel-Filled Soakaway
This is a pit filled with clean, angular gravel. It is simple to build but takes up more space for the same water capacity.
Modular Plastic Soakaway Crates
These are lightweight, interlocking units that create a large void for water storage. They are easy to install, take up less space, and store more water than gravel designs.
Key Considerations Before Installation
Before you install a soakaway, several important checks are necessary.
Soil Permeability Test
A percolation test measures how quickly water drains through the soil. Without this test, you risk installing a soakaway in unsuitable ground.
Water Table Levels
The soakaway should be above the highest seasonal water table to ensure proper drainage.
Location and Distances
Regulations require soakaways to be at least five metres from building foundations and two and a half metres from boundaries.
Correct Sizing
The soakaway size should match the roof or surface area it serves, as well as local rainfall patterns. Oversizing is safer than underestimating capacity.
Common Mistakes to Avoid
Even a well-built soakaway can fail if installed incorrectly. Avoid these errors:
- Installing in clay-heavy soil without testing drainage speed.
- Positioning too close to buildings or boundaries.
- Forgetting to include a silt trap.
- Using poor-quality materials that degrade over time.
Step-by-Step Guide to Soakaway Installation
Although professional installation is recommended, understanding the process can help you plan.
- Site Assessment – Measure the surface area to be drained and perform a percolation test.
- Excavation – Dig the pit to the correct size and depth.
- Lining – Place the geotextile membrane to wrap the chamber.
- Chamber Placement – Install soakaway crates or fill with clean gravel.
- Connection – Attach the inlet pipe from the downpipes or drains.
- Wrapping – Fold the membrane over the top to seal it.
- Backfilling – Replace soil and compact the surface.
Maintaining Your Soakaway
While soakaways need little maintenance, a few simple steps keep them efficient.
- Clear gutters regularly to prevent blockages.
- Keep the area above the soakaway free from heavy vehicles.
- Watch for slow drainage or pooling water and act quickly if problems arise.
Soakaways and Sustainable Drainage Systems (SuDS)
In modern construction, soakaways are often part of a larger sustainable drainage system. SuDS combine methods like permeable paving, rain gardens, and green roofs to manage water more naturally. Including a soakaway in a SuDS plan improves water quality and reduces flooding.
Frequently Asked Questions
How long does a soakaway last?
A well-installed soakaway can last over 20 years with minimal maintenance.
Can I install a soakaway myself?
While possible, professional installation ensures compliance with regulations and optimal performance.
Will a soakaway work in clay soil?
Clay soil drains poorly, so soakaways are usually not recommended without significant modification.
Why Choose Drainage and Plumbing LTD?
Our team has extensive experience with this system installation and maintenance in South East England, and as a result, we fully understand local ground conditions, as well as the weather patterns and building regulations that can affect your drainage system.
We provide:
- Fast response times with 24/7 availability.
- Skilled, fully equipped engineers.
- Transparent pricing with no hidden costs.
- Complete drainage services, including CCTV surveys and blocked drain solutions.
Contact Us for Expert Soakaway Solutions
If you need advice, installation, or repairs, call Drainage and Plumbing LTD today. We offer reliable, professional, and friendly service across South East England.
📞 Phone: 07771 200075
📧 Email: support@drainage-plumbing.co.uk
🌐 Website: drainage-plumbing.co.uk
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