Soakaway Installation Guide: Managing Surface Water

With increasingly heavy rainfall in the UK, managing surface water effectively is more important than ever. If rainwater from your roof, driveway, or patio isn't draining properly, it can lead to severe waterlogging, localized flooding, and even structural damage to your property.

One of the most effective and eco-friendly solutions is a soakaway. At CleverWorks, we specialize in surface water drainage solutions across London. Before any installation, we highly recommend a CCTV drainage survey to assess your existing surface water pipes and ensure they aren't simply blocked.

What is a Soakaway?

A soakaway is a buried drainage feature designed to manage surface water. Traditionally, they were simply large holes filled with rubble or stones. Modern soakaways use specialized plastic crates (similar to milk crates) wrapped in a geotextile membrane.

Rainwater flows from your gutters and downpipes into the soakaway crates. The crates provide a large void space to hold the water during heavy downpours. The water then slowly and safely percolates (soaks) through the membrane and into the surrounding soil, recharging the groundwater naturally.

The Crucial First Step: The Percolation Test

You cannot simply dig a hole and install a soakaway. The success of a soakaway depends entirely on the permeability of your soil.

Before installation, a percolation test must be carried out. This involves digging a test pit, filling it with water, and timing how long it takes to drain away.

• Sandy or loamy soil: Usually drains well and is ideal for a soakaway.
• Heavy clay soil: Drains very poorly. If the percolation test fails, a standard soakaway will not work, and alternative solutions (like attenuation tanks or connecting to a surface water sewer) must be explored.

Building Regulations and Soakaway Placement

The installation of a soakaway must comply with UK Building Regulations (Part H). There are strict rules regarding placement to protect your property and the environment:

• It must be located at least 5 metres away from any building foundation to prevent undermining the structure.
• It must be at least 2.5 metres away from any boundary.
• It must not be installed in an area where the water table is high, as it needs dry soil to soak into.
• It must be sized correctly based on the roof area it is draining and the results of the percolation test.

The Installation Process

If the percolation test is successful and the location is compliant, the installation process involves:

1. Excavation: Digging the pit for the crates and the trenches for the connecting pipes.
2. Membrane: Lining the pit with a permeable geotextile membrane to prevent soil from washing into the crates and clogging them.
3. Crates: Assembling and placing the soakaway crates into the pit.
4. Connection: Connecting the surface water drainage pipes to the crates.
5. Wrapping and Backfilling: Wrapping the membrane over the top of the crates, covering them with pea shingle or gravel, and backfilling the trench with soil.

Why Start with a CCTV Drainage Survey?

If you are experiencing surface water flooding, the problem might not be a lack of drainage, but a blockage in your existing system.

A CCTV drainage survey allows our engineers to inspect your downpipes and surface water drains. We often find that flooding is caused by a build-up of leaves, silt, or a collapsed pipe, rather than the need for a brand new soakaway. A survey ensures you only pay for the solution you actually need.

Struggling with surface water? Book a CCTV drainage survey today or call CleverWorks on 01932 544 095 to discuss soakaway installation.