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Soakaway Drain Installation Cost

Want to know how much it costs to have a soakaway drain installed? In this article, we’ll discuss the supply, labour, and overall cost of fitting a soakaway drain. We’ll also look at other relevant topics, including a look at the various types of soakaway drains and discussing what it involves.

Duration:
1-3 days
Average price:
£600-£1000

Introduction to Soakaway Drains

If you’re planning to have a soakaway drain fitted in the future, the following guide will prove particularly useful.

To be specific, a soakaway drainage system uses a hole in the ground at the perimeter of a property which is filled with rubble. It is often installed in a back garden.



These systems are used to drain excess water following on from high levels of precipitation. Many homeowners install soakaway drains because their current drainage system is simply insufficient.

How Much Does It Cost to Install a Soakaway Drain?

We’ll now look at the cost of installing a soakaway drain based on various sizes and job types. To install a 190 litre soakaway drain would cost about £630 to £840. The average cost is £730 to £940 to fit a 333 litre soakaway drain, £880 to £1250 for an 800 litre soakaway drain, or £1060 to £1330 to install a 950 litre soakaway drain.

As for other job types, installing a new soakaway drain under a lawn would set you back by roughly £580 to £840. If you’d like to install a soakaway drain beneath a driveway, expect to pay around £830 to £1140. To replace a lawn soakaway drain would cost around £500 to £710 and you’d be billed for roughly £630 to £940 to have a soakaway drain under a driveway replaced.

Labour Cost

The labour cost along with supply and waste removal costs make up the overall price of a soakaway drain installation price. For a 190 litre soakaway drain, the labour cost would land around £500 to £600.

You’d likely pay £550 to £650 for a 333 litre soakaway drain, £700 to £900 for a soakaway drain supporting 800 litres drainage or £750 to £950 for one supporting the drainage of 950 litres.



The labour cost would be roughly £450 to £600 for fitting a soakaway drain beneath a lawn, £650 to £850 to install a new soakaway drain under a driveway, £400 to £500 to replace a current soakaway drain under a lawn, or £500 to £700 to replace such a system below a driveway.

On average, soakaway specialists charge about £150 to £200 per day.

Supply Costs

Looking at the cost of materials specifically, you can expect to pay £100 to £200 for a 190 litre soakaway drain, £150 to £250 for a 333 litre soakaway drain, £150 to £310 for an 800 litre soakaway drain, or £180 to £340 for a 950 litre soakaway drain.

As with fitting a soakaway under lawn, the supplies would cost around £100 to £200. For installing a soakaway beneath a driveway, this would have a supply cost of about £150 to £250.

To replace a current soakaway drain below a lawn would cost £70 to £170, but replacing an existing soakaway drain under a driveway would have a supply price of about £100 to £200.

Cost Factors

How much you’d need to pay to install or replace a soakaway drainage system will depend on, of course the size/type of soakaway drain, but also the specifics of the job (i.e. where it is benign installed and if it is a new installation or a replacement job), ease of access, and location of property.



The last point is relevant given that labour prices vary from place to place across the UK. Soakaway drain prices based on labour tend to be highest in the southeast and London especially but lower in regions including north England, Scotland, and Northern Ireland.

Soakaway Drain Cost

Job Description Labour Supplies Waste Removal Total Cost
190 Litre Installation £500 to £600 £100 to £200 £30 to £40 £630 to £840
333 Litre Installation £550 to £650 £150 to £250 £30 to £40 £730 to £940
800 Litre Installation £700 to £900 £150 to £310 £30 to £40 £880 to £1250
950 Litre Installation £750 to £950 £180 to £340 £30 to £40 £1060 to £1330
New Soakaway Under Lawn £450 to £600 £100 to £200 £30 to £40 £580 to £840
New Soakaway Under Driveway £650 to £850 £150 to £250 £30 to £40 £830 to £1140
Replace Soakaway Under Lawn £400 to £500 £70 to £170 £30 to £40 £500 to £710
Replace Soakaway Under Driveway £500 to £700 £100 to £200 £30 to £40 £630 to £940

Types of Soakaway Drain

In this section, we’ll discuss the key types of soakaway drains and look at their pros & cons, how they differ, and which is the cheapest or most expensive to install/replace.

Bore Hole Soakaway Cost

This type of soakaway tends to have a diameter of 6” and exists as a vertically-oriented perforated pipe. Borehole soakaways are typically used when it is revealed through a percolation test that the property’s ground conditions aren’t suitable for a drainage field.



They may also be installed if space is insufficient. For this soakaway to work, a trial borehole would be needed with a depth of 10 metres. This would be needed to establish whether a borehole soakaway is suitable to begin with.

Pros:

✔ Well-suited if ground conditions do not suit a drainage field

✔ Ideal if space is insufficient

Cons:

✖ May not always be suitable


Drainage Field Cost

This type of soakaway drainage system is a network consisting of slotted or perforated pipeworks. These pipe networks may run from a sewage treatment plant or a septic tank.

Drainage fields offer a way of treating wastewater by allowing it to percolate through subsoils in a safe manner that does not result in ground pollution.

The structure and size of a drainage field will depend on the findings of the percolation test. There has to be a certain amount of space in order for a drainage field network to be fitted.



In addition, property ground conditions will not always be suited to the installation of a drainage field.

For example, if the soil is too wet or too dry, a drainage field may not suffice. Percolation tests can also determine the state of the soil conditions.

Pros:

✔ Can treat wastewater

✔ Eco-friendly

Cons:

✖ May not suit all ground conditions

✖ Will not suit spaces that are too small


Soakaway Chamber Cost

Soakaway chambers are often used when there is insufficient space for a drainage field even if the ground conditions are suited to a drainage field.

A professional will need to undertake a trial excavation to establish if the ground is suited for a soakaway chamber at the right depth.

Pros:

✔ Suited if not enough space for a drainage field

✔ A trial excavation is needed

Cons:

✖ Not always suitable


Rubble Filled Pit Cost

This type of soakaway drain is a form of excavation filled with rubble. A solid pipe is used to discharge waste to a septic tank.



It is a more traditional type of soakaway and is rarely used nowadays. It is not deemed a suitable way of managing septic tank discharge nowadays.

Pros:

✔ Long-lasting solution through history

Cons:

✖ Not common these days

✖ Generally deemed unsuitable


What Does Installing a Soakaway Drain Involve?

In this section, we’ll delve into the steps involved in building a soakaway drain and establishing this type of drainage system.

1. Hiring a Contractor

The first step is to find the right professional or company for the job. In order to achieve this, it’s worth asking for quotes from three separate contractors/companies as well as references.

A contractor/company will then come by and undertake the necessary tests/surveys to establish what type of drainage system is suitable and where it should be installed.

The contractor/company will then go about sourcing the materials before returning to install the soakaway drainage system.

2. Install Pre-Filters

On the day of the installation work, the first practical step needed to build a soakaway drain will involve having a pre-filter installed.

Geotextile membranes can be used to stop soil from the surrounding land being washed away by the soakaway but a pre-filter is more effective. A silt filter trap is an advisable type of pre-filter worth considering.

3. Excavation

Next, the hole itself will be dug out carefully and precisely. Should the installation be taking place in a garden, it’s important that turf is removed cautiously in such a way that it can be returned to its original position post-installation.

Each soakaway drainage system and installation job will have its own specifications as to how deep the crates that make up the drainage system will need to be fitted.

The bottom and sides of the excavation should be straight and square.

4. Fitting the Crates

Once the site has been properly excavated, it’s time to install the crates. In many cases, the crates must be connected with clips or cable ties, though it depends on the specifics of the system.



The cables and clips will be removed after the installation is complete since they provide no structural support.

Once the crates are in position, the soakaway may be hooked up to the water drainage system. All necessary pipe connections should now be made.

5. Backfilling

As you may suspect, this next step involves filling the excavated holes with material to cover the crates.

Sand or pea shingle is often used to cover the sides and tops of the crates before soil can be re-fitted atop the soakaway drainage system.

6. Waste Removal

Though waste disposal is likely to be minimal (especially if the removed soil is utilised as fully as possible), it’s probable that some degree of waste removal will be required.

This may involve the company/contractor removing the waste themselves, the hiring of a small skip, or the hiring of a man and van service.

7. Additional Costs

Once the soakaway drain is fully installed, the waste has been removed and the area cleaned up, you may wish to have some added work undertaken.

For instance, on average it would cost between £1300 and £3000 to have a new driveway installed. If you want to have a new patio installed, expect to pay between £1500 to £2400.

With that said, the cost of these jobs will depend heavily on the size of the installation area and the material used.

DIY Soakaway Drain Installation

This is not a job for most DIY enthusiasts, giving the complexity and specifics of the work. If you do choose to take it on, however, various building regulations will apply.

These regulations are laid out on Planning Portal, in relation to England and Wales. However, regulations may differ for Scotland and Northern Ireland.



A contractor may need to sign off the work when complete. While planning permission approval is unlikely to apply, it is best to inform your local planning office in advance of the work.

As with any DIY work there is a risk of dangers associated with this work. Firstly, the work can involve carrying heavy equipment and using sharp/heavy tools.

In terms of a less serious risk, there is the possibility of performing an incorrect or insufficient installation.

Potential Problems and Pitfalls

There are a variety of issues and downfalls with this work worth considering. For example, installing a soakaway drain is complex and disruptive work.



If you fail to receive planning permission or building regulations approval, you will need to re-apply with the necessary changes.


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Sam J

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