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Soakaway Crates (Attenuation Crates or Cells)

Check out our huge range of different soakaway crates to suit all applications. We stock handy 1m3 soakaway crate kits for small domestic situations, but also keep in stock full lorry loads of heavy duty attenuation cells such as the Polypipe Polystorm R crate often used in large civil engineering applications. Read below for soakaway crate installation guide and video.

More Information on Soakaway Crates

Attenuation Cells Installation

We sell several different types and brands of soakaway products, for different load ratings and applications. Our one cubic metre sets are the most popular selling products. The waiting time is 2-3 day delivery for pallets, however next day delivery options are available for a single crate.

Admittedly, water is one of the most destructive elements to a building since deterioration is more rapid where it’s present.

If you’ve got water pooling around buildings, you may have heard about these systems – or, as they’re sometimes called; attenuation cells.

These crates are an extremely effective way of dispersing water, without the need for planning complex draining routes or potentially widespread works.

What Exactly is a Soakaway System, Anyway?

Standing water around buildings and water infiltration are age-old problems – as are many of the techniques used to deal with the issue.

A traditional solution involves digging a large pit; which is then filled with materials like hardcore, stones and coarse gravel. While immediately effective, this solution is fairly short-lived.

The crates (named because of their resemblance to old milk crates) are simply installed, extremely tough, can carry a significant load, and the soakaway crate is designed to never become clogged or ineffective.

Attenuation Cells Frequently Asked Questions

Can you give me some pointers on the system's installation process?

It’s important that they are installed correctly; otherwise you may not get the result you’re hoping for.

We’ve broken the installation of a 1m3 system down into 7 steps – with detail around what’s required at each of those points. You will need to adjust excavation and back fill sizes if your crates vary in size.

Step 1:

Before purchasing items and prepping power tools, air tools, and hand tools, it’s important you assess the impact that your crates could have on the surrounding area. If it is part of an extension or new build property, you may need to seek permission or advice from your local authority.

Step 2:

When you’re happy to proceed, you should mark and begin to carefully excavate your chosen area. If you’re removing turf, carefully dividing and rolling can protect the sections for use later.

Step 3:

For a 1m3 soakaway kit you should excavate a hole, which is 1.2m square – and 1.6m deep. As you’ll be aware, a hole of this size is difficult to create manually – so hiring a mini-digger will significantly reduce your timescales.

Given the uniform nature of the crates, you should aim to excavate a hole that is straight and square, housing the system neatly and applying pressure evenly across the crates.

Step 4:

Many installations require just one set of crates – which often come ready assembled. If you’re assembling your system on-site, you’ll reduce the effort required by doing so before the crates are lowered into the excavation.

Step 5:

To prevent your crates form losing effectiveness over time, you should ensure it’s wrapped in an appropriate geotextile membrane. Doing so will ensure water still disperses – but soil is not washed into the crate voids.

Step 6:

Your soakaway can now be connected to the surface water drainage system. This can be done by removing one of the preformed sections that allows for the entry of either a 100mm flexi or 110mm/160mm fixed pipe.

Step 7:

To secure and finish the job, you should fill the remaining 100mm around the system sides with a 10mm pea shingle – before applying another 100mm layer of pea shingle to the top of the system.

You should now apply another 350-400mm of soil on top of the upper later of pea shingle, making sure you firmly tamp this later down. Doing so will help counter any settlement and keep your lawn, walkway or finishing layer even.

How many will I need?

Well, that will depend on many variables including the amount of space available, the soil type and incoming/outward flow rate. A percolation test should be performed on the soil to determine the ground conditions.

For example, clay-based soil is heavy and can cause liquid waste to filter out slowly, rather than soaking away freely. This test will give the area in square metres required.

To work out what size crates are needed for your property, use the method below to give you an accurate guide. First, you’ll need to calculate the area of the roof that will discharge into it. This is calculated as follows:

Calculate the roof area by measuring the length of the roof from one end to the other along the eaves. Then measure the width of the gable end, or the hip end, and divide this number by two. Now multiply the two figures together – keep this number written down on a notepad.

Then you must allow for the slope of the roof you need to multiply your roof area figure by the factor shown below, depending upon the pitch of your roof.

Roof Pitch:

20 Degrees x Factor of 1.182

22.5 Degrees x Factor of 1.207

25 Degrees x Factor of 1.233

27.5 Degrees x Factor of 1.260

30 Degrees x Factor of 1.288

32.5 Degrees x Factor of 1.319

35 Degrees x Factor of 1.350

37.5 Degrees x Factor of 1.384

40 Degrees x Factor of 1.419

42.5 Degrees x Factor of 1.459

44 Degrees x Factor of 1.500

47.5 Degrees x Factor of 1.547

Once you have calculated your effective roof area, use the table below to work out how many crates you need:

Effective Roof Area (Square Metres)

Size needed (Cubic Metres)

Number of Aquacrate Crates Required

Number of Polystorm Crates Required

25 m²

0.5m³ (500 litres)



30 m²

0.6m³ (600 litres)



40 m²

0.8m³ (800 litres)



50 m²

1.0m³ (1000 litres)



60 m²

1.2m³ (1200 litres)



80 m²

1.6m³ (1600 litres)



100 m²

2.0m³ (2000 litres)



When should you use them?

Attenuation cells can be used on virtually any site, which would benefit from localised water infiltration such as under roads, car parks, pavements and in shopping centres or sports stadiums.

The location of your soakaways is key to its effective performance. Sandy or loamy soils are ideal for soakaways – but you’ll probably need to look into alternatives if you’re up against a heavy clay soil.

What is the Delivery Lead Time?

EasyMerchant Limited carries plenty of stock of these products so you can look forward to a 2-3 day delivery, with next day delivery available for small quantities or smaller products. Many areas can enjoy next day delivery for soakaway crates ordered by 12:00pm, however as a precaution we always ask that you leave 2-3 days for delivery.

How Far Away Do Soakaways Have to Be From a House?

The system must be at least 5 metres from the extension and 2.5 metres from your neighbours' fence. The pipe flowing to the system should be 100mm underground waste ideally, but the Building Inspector may settle for 75mm, and it should be laid to a fall of 1:40.

How Deep Should They Be?

The bedrock must not, at any time, be within 1 metre at the base of the drainage pipe itself. This means that it has to be a minimum of 2 metres under ground, at all times. The maximum depth allowed for pipework is 700mm.

Do I need planning permission?

You don't require planning permission if the surface that must be covered is less than five square metres or if the new surface is permeable or porous or in case a traditional coating is laid and the rain is directed to a lawn or border to empty naturally - or if it's led into a soakaway by means of channel drainage grates.

Are the ground conditions important?

They can only operate when the ground conditions are right. Consequently, the kind of floor sitting underneath the soakaway system should not be too damp, saturated or too dry.

This in turn will prevent it from working correctly. For instance, ground, which is mostly clay, is not acceptable, since it will not permit the liquid waste from passing through the crates fast and it isn't porous.

The sewage should always pass out down through the floor and out of this soakaway crates system. As soon as it hits the clay floor, it could travel sideways or upwards to ground level and wouldn't travel any further. This can indicate that the effluent can bubble up and swimming on the outside - not the water feature you might have had in mind for your own garden!

Do I need a peculation test before starting the installation process?

A percolation test can be utilised to choose whether the soil at a house is acceptable for a soakaway system (also called a drainage area). It's crucial that a filtration test is performed prior to a new system being installed so as to avert any impending difficulties.

Let’s have a look at why they're very important, and what is usually involved. A percolation test generally involves 3 test pits being dug, and is performed within two days.

Regulations say that it has to be a minimum of 2 test pits, nevertheless at the outcomes they offer so that we always execute three 2 pits may be restricting within our expertise.

The test pits have to be found where you would be likely to be relegated to the depth, which the soakaway crates system is to be installed, and where you will eventually place it.

Is it safe to use a credit card when ordering online from EasyMerchant?

Yes. EasyMerchant uses a well-known, secure system for online ordering that is used worldwide.

How do I choose the right products?

Geocell Soakaway crates, Polypipe Polystorm Soakaway crates and Brett Martin Soakaway crates are all high-quality soakaway crates that are available in a variety of sizes and configurations here through EasyMerchant.

This broad selection has compressive strengths that range between 20-61tonnes per square meter, so will be suitable for everything from domestic to industrial installations.

While selecting the correct soakaway crates for the installation is obviously vital for reducing surface water, you’ll significantly reduce effectiveness and longevity of your soakaway if it’s not wrapped in the appropriate non-woven geotextile membrane.

EasyMerchant’s Terram Geotextile is the ideal addition to your job – boasting filtration capabilities that make it suitable for even industrial grade separation.

Also, you may need some 110mm Underground Sewer Pipe to connect into the soakaway crates system, or sometimes land drainage pipe will be required. Both are available here at EasyMerchant Limited. It is not recommend to use a cast iron inlet pipe.

What are the components required when creating this system?

There are usually only 3 main components required when creating a soakaway system, they are:

  1. Soakaway crates / attenuation cells:

The main part of your installation and usually sold in 0.8 cubic metres and 1 cubic metre sets. To allow for jobs of all sizes and applications, individual cells are also available in a variety of smaller sizes.

  1. Clips

Clips are required to secure crates to one-another. Soakaway crate sets often come complete with clips – but you may need extras, depending on the installation. Clips are generally designed to connect your crates laterally or vertically.

  1. Geotextiles

While soakaways will somewhat disperse sediment that could cause blockages, it’s important you wrap them in a geotextile membrane. This will keep your soakaway crates effective for longer, prevent crate separation and reinforce your installation.

Why choose EasyMerchant?

  • Experience

Well, I want to think it is because we are just fantastic! But actually, the key comes down to providing our clients with expert knowledge gained through many years of experience.

  • High Quality Products

We'll always try to quality check and search for any damages or manufacturing flaws before we package any purchase, and we constantly select products that are up to BS EN standards and products which are fully compatible with one another.

  • Affordability

We use our buying power and industry connections to purchase products in huge bulk quantities to be able to bring down the cost.

  • Reliability

Your order is delivered to your property or building site on time and in excellent condition ready to perform the job at hand.

  • Excellent Customer Service

We value all our customers and go an extra mile to ensure their satisfaction. That is our promise.

  • Great Employee Experience

All EasyMerchant's employees are friendly and committed to rendering comprehensive, responsive customer services.

  • Anti Modern Slavery Policy

We are dedicated to making sure that there is no human trafficking or modern slavery in our supply chains or any part of our business.

  • Business Networking

Please know that when you view supplies on EM that they've been selected from a buyers view point so that the best products have been chosen, not just the cheapest. We work with leading manufacturers such as Kalsi Plastics, FloPlast, Osma and more.

Order from EasyMerchant Today!

Once you add to cart with EasyMerchant then your job of sourcing the correct products are done. Just leave it to us to get them to where you need them.

Fast, Free delivery is available for all orders above £120/ex VAT. Feel free to create an account when placing your order.

We keep plenty of attenuation cells in stock by well known and trusted brands including: Geocell, Brett Martin and Polypipe. All brands have are different sizes with different loading capacities etc, so please make sure you're ordering the correct system for your needs before placing the order. For ease we also sell these in sets for the most common sizes. Fell free to call or email us with any questions.