Soakaway Crates

Soakaway Crates for Sustainable Drainage Systems (SuDS)

Soakaway Crates, also referred to as water cells, attenuation tanks, or stormwater crates, are now the most commonly used method of building a surface water drainage system, offering you a smarter way to manage your rainwater.

The innovative design of our soakaway crates offers a significant saving in the amount of excavation, soil transport, and installation time needed. They are quick and easy to install without the need for any heavy machinery.

We offer a wide range of stormwater crates to suit any project, from small property developments to large-scale commercial or engineering jobs.

We sell Rainsmart soakaway crate modules. Our crates are available either fully assembled or flat-packed to save valuable space on-site and there is a wide variety of design options to suit all types of different site requirements so whether you need 1 cubic metre soakaway set to install in your back garden or a large commercial soakaway we can certainly help. In addition to the Rainsmart systems, we also stock Rain Bloc and Polypipe Polystorm Soakaway crate systems.

Our Rainsmart standard soakaway crate comes with a 24.2 tonne vertical load or if you are looking for a heavy option, our heavy soakaway crate option comes with vertical loading of up to 65 tonnes. Our Rain Bloc system comes with a 60 tonne vertical load.

Soakaway Crates & Sets

You can purchase our Soakaway Crates individually or in sets of 1 cubic metre - these sets come with sufficient geotextile membrane to wrap all of the outward faces of the soakaway. We stock Rainsmart soakaway crates in a variety of different size and layout options. The modular structure provides flexibility and if desired can allow you to create alternative sizes and shapes to fit in tight spots.

Rainsmart products are strong, easy to install, eco-friendly and very long-lasting and can be used in a variety of applications. With a void ratio of 95% these systems are vastly superior to the old style rubble soakaways and ensures a large contact area for quick infiltration while allowing more water to be stored in less space.

Additionally, our Rainsmart Ellipse soakaway crates come with a 24-tonne vertical crush load and market-leading 18-tonne lateral load offering a heavy loading capacity to allow installation under gardens, driveways or car parks. If you want something a little more heavy-duty our 65 tonne heavy will do just the job offering a vertical load of 65 tonnes. 

Soakaway Applications

Our soakaway crates can be used in a variety of applications including: 

  • Underground stormwater management - to reduce flooding
  • Infiltration - allowing stormwater held in your tank to seep back into the ground slowly over a period of time
  • Attenuation - discharge water from crates slowly to avoid downstream flooding and erosion of waterways
  • Rainwater recycling - pumps the rainwater back out of the crate system for use in irrigation and reuse
  • Grass swales - linear grass-covered gullies which take surface water overland from the drained surface to a storage or discharge system, typically using road verges
  • Road drainage - enhancement in both quality and quantity of road runoff
  • Bioretention basins - using a channel (like a swale) stormwater can be slowed and treated to desired levels by the placement of check dams
  • Sportsfield drainage - assist with flooding and recycling by removing water and storing it underground for future use
  • Channel drainage - create a linear shallow open channel to funnel stormwater
  • Carpark stormwater tanks
  • Septic and leach drains
  • Trench soakaway

Rainsmart Soakaway Systems

Rainsmart Soakaway systems are an innovative, superbly engineered range of products used in the collection and controlled discharge of stormwater. With a team led by professionals from the civil engineering and environmental fields, Rainsmart have developed a range of long-lasting, robust and eco-friendly products that provide ground-breaking solutions to the rainwater management problems presented by urban developments.

With load ratings of up to 85 tonnes vertically and an industry-leading 18 tonnes laterally, Rainsmart systems are suitable for all types of applications including infiltration (soakaways), attenuation (controlled discharge), and retention (rainwater recycling).

You can learn more about each of these different types of stormwater management in our Soakaways Guides & Tips Section.

What Are The Different Types Of Soakaways?

Standard Crates

Our standard water cells offer efficient surface water management with an innovative design that simplifies installation without requiring heavy machinery. Available in both fully assembled and flat-packed options, these crates cater to various project sizes, from residential to commercial. They boast a robust vertical load capacity of up to 24.2 tonnes & lateral load of 18 tonnes, ensuring reliable performance for stormwater management needs.

Shallow Crates

Our shallow dig soakaway crates are designed for areas with high water tables, offering efficient stormwater management with a unique shallow stacking design. Despite their shallow profile, they maintain the same capacity as a standard 1 cubic meter soakaway. These crates are ideal for manual excavation, simplifying the labour-intensive process of installation without machinery.

Shallow crates are available with vertical load capacities of 24.2 or 65 tonnes, catering to various project sizes. Whether you need ready-to-use or flat-pack options, our shallow soakaway crates are crafted for convenience to meet your specific needs.

Deep Crates

Our deeper soakaway crates, manufactured by Rainsmart, offer vertical load capacities of either 24.2 or 65 tonnes. They provide robust solutions for projects with high load demands. These crates are especially useful in areas where a deeper excavation is required due to soil conditions, or to reach a lower water table.

Available in flat-pack form, they are designed for easy self-assembly, ensuring convenience without compromising on strength and durability. Whether tackling residential drainage or large-scale engineering projects, our deeper soakaway crates are a reliable choice.

Heavy Crates

Heavy soakaway crates with a 65-tonne vertical load capacity offer exceptional strength and durability, making them ideal for projects with substantial load requirements. These crates are most often used in areas where there is heavy traffic, or where the soil conditions demand a robust stormwater management solution.

Heavy crates provide ample stormwater storage capacity, ensuring effective water management even in areas prone to heavy rainfall or flooding. Typically used in commercial and industrial settings, as well as in civil engineering projects, these heavy-duty crates are designed to withstand high load demands and offer reliable performance in challenging environments.

Flat-Packed Soakaways

The one problem that soakaway crates traditionally present both to merchants and installers is on-site storage and distribution. Crates are bulky items that take up a lot of space, so often installers will order them just prior to installation in order to save valuable space on site. Rainsmart’s innovative soakaway systems are available in a flat pack option for easy assembly on site.

Installing Your Soakaway Crates

Assembly is a simple process – the only tool required is a rubber mallet which we include with each cubic metre set. One person should be able to assemble a one cubic metre set in 12 to 15 minutes. Check out our video guide on how to build soakaway crates for more information. We also have a guide on the best practices for installing soakaway crates, from excavating your hole, preparing the base and installing your crates.

Polypipe Soakaway Systems

In addition to Rainsmart crates we also stock Polystorm systems, which are also available in pedestrian or vehicle loading options should you wish to position your soakaway under a driveway or road.

Soakaway Crate Sizes

We have a number of different sizes of soakaway crate - we offer shallow crates as an option if a shallow dig soakaway is needed. So if your property is in an area where the water table is higher than normal this could be perfect. 

The clever design of Rainsmart soakaway crates allows you to stack them all on a shallow, single layer whilst still holding the same amount of stormwater as a standard layout 1 cubic metre soakaway. 

This type of soakaway is also popular for those excavating by hand – this is a laborious and potentially dangerous scenario when installing a standard shape soakaway without mechanical means.

Soakaway crates for heavier soils are also available if there has been an issue with soil permeability. In normal permeable soils, rainwater held in the soakaway infiltrates back into the surrounding soil, recharging underground aquifers and providing moisture for the surrounding vegetation. In heavier (less permeable) soils the rate of infiltration is much slower – the clay-based soil particles form a barrier that holds the stormwater for longer within the upper reaches of the ground.

Rainsmart Heavy Soil Soakaways are designed to give a much greater soil contact area – up to four times that of a normal one cubic metre soakaway. This is achieved by creating a table shaped structure, utilising a flat 30mm water storage cell above a standard soakaway cube. This increased surface area allows rainwater to permeate the soil over a larger expanse, reducing the chance of saturation in the area immediately surrounding the base soakaway crate structure.

For any soakaway installation, we always recommend seeking advice from your local authority planning officer. If you have any doubt as to whether your soil is suitable for a soakaway a simple soil percolation test would be advisable.

What Size Should My Soakaway Be?

The design of a soakaway depends on a number of factors, such as catchment area, consequences of flooding, permeability and foundation design which are different at each site. That said, the most common and popular size for a domestic installation is 1 cubic metre. This is what the majority of local authorities have accepted during specifications when draining roof areas of approximately 50 square metres (when under normal conditions).

If in doubt, we would recommend that you should get them designed by a civil engineering consultant and seek approval from your local planning authority as often soakaways will need to be designed with a specific storm intensity and duration. If you have this information then we can help create an exact design for your need - just drop us a message or give us a call. 

Once you know the size that the system needs to be, either width, length and depth or in cubic metres then we can calculate the number of crates that are needed to make this volume. We have a variety of crates and with a modular system we can be very flexible in sizing up a system which will work for you and your project. 

Some of our most popular combinations can be seen below:

Size of Soakaway Required   (Cubic Metres) Number of Rainsmart Ellipse Shallow Crates Required Number of Rainsmart Ellipse Double Crates Required Number of Rainsmart Ellipse Triple Crates Required Number of Rainsmart 65 Tonne Heavy Shallow Crates Required Number of Rainsmart 65 Tonne Heavy Double Crates Required
0.5m³ (500 litres) 4 2 2 4 2
1.0m³ (1000 litres) 8 4 3 8 4
1.5m³ (1500 litres) 12 5 4 12 6
2.0m³ (2000 litres) 16 8 6 16 8
3.0m³ (3000 litres) 24 12 9 24 12
4.0m³ (4000 litres) 32 16 11 32 16
5.0m³ (5000 litres) 40 20 14 40 20

Soakaway Inspection & Cleaning


Installing a pre-filter before a soakaway is always a precaution that we would advise you to consider. Whilst geotextile membrane prevents soil from the surrounding area being washed into the soakaway, there is always the possibility that the stormwater pipe itself will carry silt and other debris washed in from the roof and gutters. A good silt filter trap or catchpit chamber is easy to maintain and will certainly prolong the life of the soakaway.

Linear Inspection Channels

Using our Rainsmart systems you can also create a linear inspection channel which isolates silt and debris upon entry and stops it from entering the main system. Find out more on our inspection and cleaning page.

Designing a Crate System for Attenuation

If you are looking to source crates for a geocellular attenuation tank then we offer a number of impermeable membranes that can help including a shoebox design which is used to wrap around geocellular attenuation units and is usually supplied in two fabricated pieces. The first is the base while the second is for the top with a small overlap down the sides. The two pieces effectively make a ‘shoebox’. Get in contact to find out more.

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  1. Rainsmart Ellipse Soakaway Crate Flat-Packed
    1. Code 90004F
    2. Brand Rainsmart
    £57.59 £69.11
  2. Rainsmart Ellipse Soakaway Crate Assembled
    1. Code 90004
    2. Brand Rainsmart
    £61.47 £73.76
  3. Rainsmart Ellipse Soakaway Crate Assembled - Shallow
    1. Code 90003
    2. Brand Rainsmart
    £34.11 £40.93
  4. Rainsmart Ellipse Shallow Soakaway Set Assembled 1 Cubic Metre
    1. Code 90003M3
    2. Brand Rainsmart
    £265.23 £318.28
  5. Rainsmart Ellipse Triple Soakaway Set Flat-Packed 1 Cubic Metre
    1. Code 90005M3F
    2. Brand Rainsmart
    £257.47 £308.96
  6. Rainsmart Ellipse Triple Soakaway Crate Flat-Packed
    1. Code 90005F
    2. Brand Rainsmart
    £89.28 £107.14
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