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Article 296 [ added on 12-10-2009, updated on 12-08-2010 ]

Planning Permission  

In normal domestic situations the formation of a soakaway does not require Planning Permission.

If the dwelling is situated in a “designated area” i.e. Conservation Area, Listed Building, National Park or Area of Outstanding Natural Beauty, Planning and other permissions may be required.

Building Regulations

Soakaways come under the section Part H - Drainage and waste disposal in the Approved Documents of the Building Regulations.

Soakaways should be sited so as not to have an adverse affect on the sub structure of the building it serves.

Apart from the Building Regulations there are various “good practices” regarding the positioning of a soakaway.

•    Avoid sitting with in 5 metres of a road or highway.
•    Avoid sitting with in 2.5 metres of a boundary.
•    Note that areas with a high water table are likely to be unsuitable.
•    Any new soakaway should not compromise existing systems.
•    Polluted run off water should not be introduced into the ground – alternative measures will be required.

General Information

The installation, the design and the construction of soakaways is governed by the Environment Agency.

Soakaways are one type of “infiltration device” a simple way of dispersing surface and storm water. The basic principle is that of a reverse well i.e. (a hole­in­the­ground) that loses water rather than collecting water. They are one of the key technologies for SUDS (Sustainable Urban Drainage Systems) and enable storm water to be dealt with “at the source" rather than being diverted into the sewer systems.

One of the first things to consider when choosing a site for a soakaway is the water table (saturation line). This is defined as upper level of the groundwater that is naturally held within the soil, sub-soil or bedrock.

Permeable sub-soils such as sands, sandy loams, along with permeable bedrock types, such as limestone, sandstone or chalk, are usually good news for soakaways, whereas hard, igneous rocks, such as granites and basalts, and heavy soils may mean a soakaway is not going to be feasible.

Types of Soakaways


•    Storm Water Soakaway
•    Infiltration Unit Soakaway
•    Trench Soakaway
•    Herringbone Soakaway
•    Looped Soakaway
•    Concrete ring slab
•    Septic Tank Soakaways
•    Infiltration Unit Soakaway
•    Trench Soakaway
•    A combination of the above Soakaways


•    Septic Tank Soakaway
•    Interceptor Soakaway
•    Storm Water Soakaway
•    Sewage Treatment Plant Soakaway
•    Trade Effluent Soakaway

Soakaway Construction

Many older soakaways are little more than a hole in the ground filled with old bricks, clinker or gravel, but such a structure has a severely reduced storage capacity and modern soakaways are, usually, empty chambers of one form or another.

Ready-made systems are available from Builders or Civil Merchants in pre-cast concrete or plastic. They tend to be circular sections that can be stacked to give the required depth and storage volume, and then topped with a suitable cover.

Soakaway Maintenance

An older soakaway may cease to function; this is usually because the structure has become blocked with silts and muds. The most effective remedy is to excavate the structure and re-build it from scratch, but with a chambered soakaway that has been partially filled with gravel or rubble, it may be possible to remove the fill material and accumulated silt to rejuvenate the soakaway.


Where possible soakaways should be built on land lower than or sloping away from buildings. Soakaways should generally be sited at least 5m from the foundations of a building.

Small Soakaways

Small soakaways are holes filled with granular material e.g. broken brick, crushed rock or gravel with particle size 10mm to 150mm. PVC sheet or concrete blinding should be laid over the fill to prevent topsoil being washed down into the soakaway.

Large Soakaways

A large soakaway is a pit lined with dry jointed or honeycomb brickwork. Alternatively perforated precast concrete rings or segments may be laid dry and surrounded with granular material.

The volume of large soakaways should be calculated to ensure they are of suitable capacity.

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