How to avoid a blocked soakaway system

A soakaway system is designed to hold excess rainwater and release it slowly into the surrounding soil to prevent waterlogging and flooding. Twinwall or coil pipes underground feed into a stack of soakaway crates which hold the water. These crates are wrapped with a permeable membrane which lets water slowly ebb out underground. The entire system is underground so it’s not that easy to treat a blocked soakaway.


With our brief guide to how to identify problems and how to fix or avoid them, you should be able to maintain your soakaway system well enough that you don’t experience any blockage issues.

Table of Contents

1. Identifying a blocked soakaway

2. 3 reasons for a blocked soakaway

3. How to avoid a blocked soakaway

clay-soilIdentifying a blocked soakaway

One of the first indicators of a blocked soakaway will be waterlogging. If the usually slightly damp ground is now logged with standing water or flooded, this is a key indicator that a soakaway below ground is blocked.

Another indicator is dips in the ground. This happens due to compacted soil, which causes the ground to sag as the soil compresses and essentially takes up less space. Compacted soil (as on the left) will mean no more water can penetrate the surrounding soil, causing a build up of water in the soakaway crates. This will in turn lead to the pipework backing up and flooding the surrounding area.

If any of these symptoms are present, then it’s sensible to say there’s an issue with your soakaway.

How are these issues caused?

There are just 3 common reasons for a blocked soakaway system. To understand  what these are, here are the 3 reasons for a blocked soakaway explain:

Silt and sediment

Silt and sediment can build up in a soakaway system easily if the non-woven geotextile is compromised or if the soil is getting into the pipework via perforations.

Compacted soil

As mentioned above, compacted soil is caused by the soil particles being too close together. Often indicated by hard and dry soil, water is unable to penetrate this soil and results in waterlogging. This can happen after installation of a soakaway system for many reasons including an unusually long dry spell, excess pressure put on the soil and the natural drying and wetting process of soil. Shown to the right is a waterlogged field.

Drain collapse

Possibly the most detrimental of the 3, the pipes that feed the soakaway system could collapse due to external pressure or poor installation. If the pipes collapse the soakaway will leak out rapidly from this if they become disconnected. If this is the case the entire system will need to be replaced.

How to avoid a blocked soakaway

It seems obvious to say that installing the soakaway system correctly first time is the best way to avoid a blocked system, but it is! Naturally occurring things can cause blockages but realistically by installing a soakaway system prudently you can avoid most issues. With modern, plastic soakaway crates a soakaway system should last many years.

Choose the right people to install the right soakaway crate

When a soakaway is due to be installed make sure you’ve got a reputable tradesperson or company. Don’t be afraid to ask questions and query why they’re choosing to do (or not to do) something! Choose the correct soakaway too. A domestic soakaway crate won’t fair well in a high-flow commercial soakaway system as it won’t be able to cope with the amount of water. Work out how many soakaway crates you need and don’t be afraid to add extra just to be cautious!


Eliminate the risk of sediment and soil


Choose a non-woven geotextile or a catch-pit to remove the risk of soil, sediment and other small items entering the soakaway system. The non-woven geotextile wraps around the crates to prevent soil from entering whilst the catch-pit in installed just before the pipe feeds into the soakaway to catch soil and particles from entering the system.

How to fix a blocked soakaway

There are 2 methods of fixing a blocked soakaway, and they both involve digging up the soakaway unfortunately. The 1st method is to dig up the soakaway, remove all the pipes and crates and re-install a new system. This is most common if the membrane is broken, the crates are the wrong size or capacity, or if the pipes have collapsed.

The 2nd method is to dig up the soakaway system and clean out wherever there’s a build up of sediment. Once this is done you can look at the system and understand where the sediment is coming from and replace this component. Is there a tear in the membrane? Has the catch-pit become too full?

Contact our drainage experts on 01752 692 221 or use our live chat in the bottom right corner for immediate advice and guidance on soakaway crates and systems. 

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