How Much Does it Cost to Build a Soakaway?

Explanation of what a soakaway is

When you can and can't use a soakaway

A soakaway price guide - updated for 2020/21

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How Much Does a Soakaway Cost?

A rainwater soakaway is essentially a hole in the ground that collects rainwater from driveways, patios and roof gutters etc. As the hole fills up, the water gradually seeps through the soil beneath and into the watertable.

The purpose of this soakaway is to temporarily store rainwater that could otherwise lead to surface flooding or the overwhelming of sewer systems.

Domestic soakaways are usually found under flower beds, lawns or even driveways and patios.

Since 2008, all newly constructed driveways must have rainwater management in place, no new driveway should allow rainwater to drain onto the public footpath or highway (see driveway drainage regulations here). A soakaway is one of several drainage options for driveways and gardens in general.

Corewater crates

Image from Core Landscape Products – (buy their soakaway products here)

In This Price Guide, We’ll Look at:

What work is involved with installing a new soakaway?

Which materials are used?

How long does a project like this take?

Also, we’ve published two price examples; one for a straight-forward soakaway installation and the second for a more complex project.

+ we’ll point you in the right direction so you can get a custom quote.

How is a Soakaway Constructed?

The first step is to determine if the ground conditions allow for a soakaway to work.

If the soil around your home is made from heavy clay, then the rainwater in the soakaway could take so long to soak away, it would be pointless to construct a soakaway.

Also, if your property is in a low area, your garden could be close to the watertable, which would make the project unviable. Imagine digging a 1-metre hole in a pond, it would quickly fill up with water, and nothing would drain away. The same thing happens to soakaways constructed into the groundwater level.

Step 1 – dig a small hole 300mm x 500mm and fill with water. The speed at which the water seeps into the ground is measured to determine the rate of percolation.

Step 2 – optionally, on a dry day, dig a test hole 1.2 metres deep, cover and leave for 24 hours. If on inspection, the hole has filled with water you’ll know it will never function as a soakaway.

Assuming the test holes prove the project is viable, the construction of the soakaway can begin.

Materials

A typical domestic soakaway will require hollow plastic crates that contain a large enough void to hold water but are strong enough to stop the hole collapsing in on itself.

A mesh or membrane is used to stop soil blocking the void and pipework is need to transfer the rainwater from the gutters, driveway, patio etc to the soakaway.

The cost of the soakaway materials for a typical domestic project is around £200.

The images below help to explain what these materials are and why they’re needed:

Soakaway Crate

A strong but hollow plastic crate to hold the rainwater

Underground pipe

Drainage pipe 

pipe bend for underground drainage

Drainage pipe bend

Drain hopper head

Hopper head, often found in patios, nr driveway etc

Non woven membane

Membrane to filter water – prevents soil from blocking the soakaway

Gravel

Gravel and sand is used around and under the soakaway

We Asked 29 Landscape Gardeners to Provide Us With Prices

See how much a new soakaway will cost (and get a customised quote)

In late 2020 we asked 29 landscape gardeners from various locations around the UK to give us quotes for a new soakaway.

Quote 1 was for a straight-forward project in a lawn with good access. It doesn’t get much simpler than this; dig a hole, a trench and lay the materials in place before backfilling with soil and some grass seed to finish off.

Quote 2 involves lifting sections of a driveway and path, installing the soakaway to a deeper level to bypass the clay soil and finishing off by re-laying the sections of driveway. This is a more complex project and the extra costs reflect the difficulty in lifting sections of a driveway and the deeper hole.

If you’re looking for a guide to how much a soakaway costs, use our figures as a better-than-ballpark price but note the following:

  • All the figures displayed below include VAT where applicable.
  • A percolation test is done by the company prior to the work starting.
  • 5 x soakaway crates included (that’s enough for a 60 sq mtr driveway as an example)
  • Prices include the purchase and collection of all pipework, filtration membrane, gravel etc.
  • Excavation of the ground for the pipe and the hole for the soakaway crates.
  • Laying of pipe/crates membrane and gravel etc.
  • Re-laying of soil/grass seed and for the second quote, the driveway surface and base layers.
  • All waste material is taken away and disposed of.

Soakaway Price 1 – In Lawn or Flowerbed

A soakaway installed under a lawn or flowerbed, some pipework and backfilling.

No tree roots, no concrete, tarmac, or anything other than soil to excavate.

It doesn’t get easier than this:

LocationFrom:To:
London Area£850£1000
South, SW and Midlands£800£900
Outer Region and North£600£800
Need a Custom Price? Get a Quote

Soakaway Cost Guide 2 – Under a Driveway

This is a more complex project and requires reinforced crates that will hold the weight of the vehicles; extra depth is required due to the presence of clay soils near the surface.

Sections of the driveway need to be pulled up for the trench and the hole, this will need to be “made good” afterwards.

This isn’t a project that can be completed in half a day; it’s disruptive and requires extra materials and labour.

LocationFrom:To:
London Area£1900£2300
South, SW and Midlands£1800£2200
Outer Region and North£1700£1900
Need a Custom Price? Get a Quote

How Long Does it Take to Install a Soakaway?

The simplest of projects will take two workers around half a day, but more complex projects will require extra time to excavate and “make good” the surface.

We would be surprised if a soakaway project took more than two days, but it’s possible, depending on the type of surface. For example, pattern concrete driveways are almost impossible to repair, and they usually need to be completely relaid.

The length of the pipe trench also affects the timescale – a five metre long and shallow pipe trench won’t take long to dig out, while a twenty-five metre long and much deeper trench would. Again, it depends on what the worker is digging through.

As a broad estimate, it will take between half a day and two days to install a soakaway and make good the surface.

These May Affect The Cost of a Soakaway Installation:

Our prices guides are for typical domestic soakaway installations. You’ll pay a different amount if:

The soakaway is bigger – needless to say, the bigger the soakaway, the more it will cost. The photo below gives you an idea of how gigantic soakaways can be:

Large soakaway project

Image sourced from Gutter Supplies

The surface material – we cannot emphasize enough how much the surface material affects the price. Digging a 2 metre-deep hole in a lawn is easy and takes very little time with a mini-digger. The same hole (and trench) through solid concrete, perhaps under steps etc is completely different.

As part of another project – if you need a soakaway and most of the groundworks have already been completed then the price may be less than the figures we’ve provided. For example, if you’re having a new driveway installed then you don’t need to pay twice for the old drive to be excavated and you don’t pay twice for the new driveway to be laid.

The Next Step

Let Us Help You Find a Good Landscape Gardener

Get a Custom Soakaway Quotation Today

Estimates like ours can be helpful for budgeting and are certainly insightful, but the prices are based on examples that may differ from your project.

For projects like soakaways, where the finer details can be the difference between a £500 project and a £3000 one, we suggest you source at least three quotes from local landscape gardeners. 

Let us help you today:

  • Get an accurate price based on the details of your soakaway project.
  • A fast service, no chasing disinterested tradespeople, get a price in hours, not weeks.
  • Read reviews and feedback from past customers that have been checked and confirmed as legitimate.
  • Compare prices online from several firms, all in one place.

Rainwater Soakaways

Get a Quote Online For Your New Soakaway

Soakaway Question and Answers

Can a Soakaway be Used to Stop Garden Flooding?

This depends on why the garden is flooding. A good landscape gardener should be able to determine this by examining the land and conducting a percolation test or digging a test pit.

In general; soakaways don’t work well or at all in very heavy clay soils or when located too close to the water table.

If you have a steep garden and are worried about surface rainwater flowing too quickly downhill and flooding an area, french drains and soakaways may help, assuming the ground is suitable.

When Were These Soakaway Prices Published?

We published this cost guide in Autumn 2020 and we don’t expect the prices to change too much over the next few years.

Where Did These Prices Come From?

We asked 29 landscape gardeners, including large firms and small traders, to provide us with prices. The figures shown in the tables above are an average of the prices supplied to us.

Do I Need to Get Planning Permission For a Soakaway

In most cases, no you don’t need planning permission to install a soakaway. You will need to ensure that its design and location meet building regulations though.

You can find more information about building regulations here.

Are There Any Landscaping Associations Where I Can Find Reputable Installers?

This type of project can be completed by any competent landscape gardener. The Britsih Association of Landscape Industries (BALI) has a list of vetted tradespeople, as does the Association of Professional Landscapers (APL).

You can use our network of tradespeople to find a good quality installer and of course, there’s also Checkatrade, Trustmark, Which? and other general trader associations you can use.

Where Can I Find Technical Information About Soakaways?
Tony McCormack’s The Paving Expert is by far the best place for technical information related to hard landscaping and soakaways in the UK.

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