Drainage of new developments in
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.
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.
The main guidance documents for the design work are 'Approved Document H' and the Environment Agency document PPG4 'Treatment and disposal of sewage where
no foul sewer is available'.
We have a strong capability in the design of all types of drainage for new developments including those in country areas, please
for more details.