Soakaway Installation Cost
Last updated 18th July, 2025
What does a soakaway drain cost?
All you need to know about the associated costs of installing a soakaway, including materials, labour and time frames. We discuss the different types of soakaway, drainage prices, as well as much more!
Continue reading for more information!
How Much Does it Cost to Install a Soakaway?
The average cost to fit or replace a soakaway is typically around £700 to £1,000.
The price depends upon numerous factors, including:
- Whether the soakaway will be installed under your lawn or driveway.
- Which type of soakaway you choose.
- How straightforward it is to access the site.
- What the ground conditions are like.
- The depth of excavation required.
- How much additional pipework is needed.
- Where you live.
Soakaway Drainage Prices
Below are some estimated costs of hiring a tradesman to install a soakaway:
| Job Description | Avg. Cost | Duration |
|---|---|---|
| Install a New Soakaway under Lawn | £650 - £900 | 1 day |
| Install a New Soakaway under Driveway | £950 - £1,300 | 2 - 3 days |
| Replace Existing Soakaway under Lawn | £550 - £800 | 1 day |
| Replace Existing Soakaway under Driveway | £750 - £1,100 | 2 days |
Table of Contents
Additional Costs
There are other jobs you may want to have completed at the same time as your new soakaway installation.
These may help your overall drainage system work properly or improve the overall aesthetic of your property.
Here are some common complementary projects:
Driveway Work
Installing a soakaway underneath your driveway could be the ideal opportunity for a driveway refresh.
There are various materials available for driveways, including gravel, tarmac and block paving. Each of these options has different costs attached, so the price of a new driveway can vary dramatically.
As an example, the cost of a resin driveway per m² is around £60 to £90, while the cost of a tarmac driveway starts from around £40 to £50 per m².
Gutter Repairs or Replacement
Ensuring that your gutters are working efficiently and are directing water towards your soakaway will help reduce the prospect of property damage later on. So, it's worth checking if you need any repairs or replacement work.
This can be an economical upgrade, with the typical gutter repair cost around £120 to £180.
Drainage Repairs or Relocation
Soakaways work alongside your home's drainage system to remove wastewater, so it's important that it's all working correctly.
If you've noticed any issues with your drainage, look into the cost of repairing a drain.
New Septic Tank
If you're replacing an existing soakaway with a new one to work alongside a septic tank, you may want to consider replacing the septic tank as well. This can reduce upheaval later on, especially if your septic tank is damaged or nearing the end of its lifespan.
On average, the cost of installing a septic tank is around £1,500 to £2,000.
Cost Breakdown
Individual costs for hiring a tradesman to install a soakaway under a lawn - Total Cost: £700
Materials
£140
Tradesmen
£525
Waste Removal
£35
Labour Costs and Time Frames
A soakaway specialist will often charge around £150 to £200 a day in labour costs.
The tradesmen will likely work in pairs to fit a soakaway and shouldn't take any longer than a day in most cases to complete the work. If the soakaway is to be installed under a driveway, then expect it to take 2 to 3 days.
| Job Description | Duration |
|---|---|
| Install a New Soakaway under Lawn | 1 day |
| Install a New Soakaway under Driveway | 2 - 3 days |
| Replace Existing Soakaway under Lawn | 1 day |
| Replace Existing Soakaway under Driveway | 2 days |
What is a Soakaway?
A soakaway is a large hole that traditionally was filled with large bits of debris such as bricks and hardcore, but today a better system is used, known as modular attenuation cells.
These cells resemble old milk bottle crates and are made of lightweight plastic with a high void ratio, which allows them to be buried in the ground to provide a storage area for water, allowing it to slowly percolate into the surrounding soil.
Because these crates are also strong, they can be buried under a layer of soil and grassed over. The crate system does not get blocked with silt quite so easily.
Why Install a Soakaway
Rainwater, either from roof guttering or a drainage channel, is a key reason why you may need a new soakaway.
First of all, soakaways often become blocked or even occasionally collapse due to the weight above them. Alternatively, if you have extended your home, sometimes the extra rainwater may be too much for your existing soakaway to cope with.
Current building regulations require that when having a new driveway or patio, you must allow for the adequate drainage of surface rainwater within the property boundaries. A soakaway is the perfect answer to these regulations.
Soakaways are very popular with planners as they are one of the key technologies for SUDS locally, rather than being diverted into the already over-burdened sewer systems. It should be noted that soakaways rarely work on heavy clay soils.
In fact, the two determining factors for soakaway success are the size of the area and the percolation rate of the soil. Another point to consider is the water table or saturation line. The upper level of the groundwater is naturally held within the soil. As in waterlogged sites, it is often found that the water table is exceptionally high and, in cases such as this, a soakaway will not work and will, in fact, become just a hole full of water.
What Does Soakaway Installation Involve?
The removal of an existing soakaway and replacement with a crate-based system, assuming the hole and pipework is through a lawn or similar and not a driveway, would entail digging up the existing drainage pipe, then laying gravel into the base of the trench.
Next, the old soakaway would be dug up to a depth of 1.2 metres and a water permeable test would be carried out to ensure the water soaks through the soil (this won’t work with some clay-based soils).
Then gravel is laid into the base of the hole, followed by crates and new drainage pipes connected to crates. Finally, the membrane would be laid over and around crates, and then everything would be covered up with topsoil, and then the soakaway drainage pipe would be connected to the rainwater downpipe.
Soakaways store the immediate storm water run-off, acting as a buffer to prevent surges of rainwater from overwhelming the drainage systems and causing floods. They allow steady infiltration of stormwater into the adjacent soil.
The time taken for complete discharge depends on the soakaway shape and size, along with the soil characteristics.
FAQs
If creating a new soakaway, then a survey will have to be carried out in accordance with BRE Digest 365. The calculation process for this is quite complicated so you should seek professional advice when planning a soakaway. You will find that when you seek planning permission for a range of permitted developments, such as installing a driveway, you will almost certainly be required to have a method in place to deal with the drainage from the driveway. A soakaway is a fairly common way to deal with this additional surface water.
Older soakaways will sometimes cease to function because the structure has become blocked with debris and mud. The most effective way to resolve this is simply to dig out the structure and rebuild it, using chambered soakaways that have been partially filled with gravel or rubble. Although it is sometimes possible to remove the accumulated materials to rejuvenate the soakaway, it is usually quicker just to rebuild it anyway.
