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Cottages Barn

Barn for sale, near Pencoed, south Wales, 2003.

Barn for sale, near Pencoed, south Wales, 2003.

Drainage of new developments in
rural areas

Special problems

The drainage for new buildings and barn conversions in rural areas presents special problems since it is likely that there will be none of the existing drainage infrastructure such as public sewers common in urban areas.

Septic tanks

Small developments in rural areas often use a septic tank to dispose of the foul sewage. A septic tank acts as a small sewage treatment works and it is usual to dispose of the partly treated effluent from the tank into the ground via a 'drainage field'. This is a network of pipes which disperses the effluent over an area to allow the natural processes in the soil to treat the water.

Package sewage treatment works and cesspools

In some circumstances, for instance where a drainage field is not feasible or if a very high standard for the final effluent has been specified, a small package sewage treatment works can be used. A further option is to use a cesspool although these need regular emptying and the Environment Agency and Natural Resources Wales do not encourage their use.

Surface Water Drainage

According to the Building Regulations document, 'Approved Document H', the disposal of surface water from the roofs of new buildings, in order of preference, should be to soakaways, to a watercourse or to a sewer. In the majority of cases the latter will not be an option. In any event it will probably be necessary to carry out a soakaway test at the site either to determine the appropriate parameters to use in sizing the soakaway or to demonstrate to the building inspector that soakways are not feasible.

Design standards

The main guidance documents for the design work are 'Approved Document H' and the section of the Environment Agency's website dealing with 'Discharges to surface water and groundwater: environmental permits'.


We have a strong capability in the design of all types of drainage for new developments including those in country areas, please contact us for more details.


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