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Southampton Soakaway Installations

With the UK’s weather getting warmer and wetter, more properties being built, and tarmac being laid, our drains have to cope with an increasing level of water run-off. In areas where there are few watercourses or suitable drain systems, soakaways have to be employed if we are to avoid larger areas of ground becoming waterlogged or sodden.

If someone has told you to dig a hole in the ground and fill it with gravel or rubble, you’ve been talking to the wrong person. No1PHD Southampton has highly trained drainage engineers who are well versed in the building regulations appertaining to the installation of efficient soakaways for both residential and commercial properties.

What is a soakaway

At its most basic, a soakaway is a large, deep hole dug in the ground to a given depth, and can be round, square, or rectangular. Depth and size of the hole vary, depending on the amount of rainwater run-off from the surrounding building’s roofs and gutters, and the speed at which the water is able to soak into the underlying substrate.

Our Southampton soakaway experts at No1PHD will initially dig a pilot hole to examine the sub-soils, determine how far down the water table is, and how far down the soils become more porous. Depending on their findings they might fill the borehole with water, and time how long it takes to soak away. A common formula for defining the required size of a soakaway is Vol = A x (rainfall rate/3000). For calculation purposes, storm rainfall in the UK is deemed to fall at 50mm/hr.

Where do you put a soakaway?

A soakaway currently has to be at least 5 metres from the foundations of any building or road, to ensure water doesn’t soak into foundations or damage the road. It also has to be 2.5 metres from any boundary, to make sure the water doesn’t flow into a neighbour’s property. It’s not uncommon for soakaways to be dug in the middle of a back garden. In this situation, No1PHD will then direct the rainwater flowing into the gutters and downpipes through a filter into a new gully, and then into newly laid drain pipe which slopes to the soakaway.

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Absolutely blown away by the service we received. Took all the stress out of losing our heating and hot water. Highly recommended!

5 star review

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Mr Wells

2 weeks ago

Couldn’t have asked for a faster resolution to our drainage conundrum. Nothing was too much for these guys who were brilliant throughout.

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Miss Carey

1 month ago

What if the soil is clay?

Certain substrates provide additional problems when a soakaway is required. This is why No1PHD begins with a test bore-hole. Hard sub-soil types such as granites, basalts, and clays retain, or slow surface water draining through, while soils like sand, loams, and gravels allow the water to drain freely. No1PHD Southampton drainage engineers can use a number of formulas to decide what the best course of action is. Whether to position the soakaway below the clay topsoil but above the water table, or to make the soakaway larger to compensate for the reduced percolation.

What material goes into a soakaway?

Remember that rubble or gravel? Yes, years ago that was what went into a soakaway, making them very inefficient as the rubble reduced the amount of water they could hold. Then came circles or rectangles of bricks or blocks, laid with ¼” gaps for the water to flow through into the surrounding soil, or large precast concrete rings which fitted on top of each other, with gaps to allow the water to escape. Nowadays, for most soakaways, No1PHD use lightweight, recycled, purpose built plastic crates enclosed in a felt membrane, making the job easier for us – and cheaper for you.

Contact Us

If you need a soakaway which isn’t just a hole filled with rubble, contact No1PHD Southampton on 01425 208031, and ask to speak to one of our professional drainage engineers, or email us at;

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After noticing that the house was unusually cold, we found that the heating wasn’t coming on and that our hot water had also failed. We called the team at No 1 PHD who dispatched an engineer to investigate. After discovering that the culprit was a faulty boiler part, they ordered in a new part and got it fitted as quickly as possible. The guys were great, and we couldn’t be happier.

Mr Lincoln

5 stars
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For days, we’ve noticed a foul smell coming from outside and a gurgling sound coming from one of the drains. Whenever it would rain, the area around it would flood slightly and take ages to drain. We tried buying drain unblockers, but none seemed effective. Eventually, we turned to No 1 PHD and were left wondering why we didn’t do this sooner.

Mrs Griffin

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