Sewerage systems

Design and installation of sewerage systems to convey foul effluent from gullys and laterals through small bore drains and sewers to the main (public) drainage system. Our designs seek to utilise the topography of the site to avoid or minimise the need for pumping. 

Systems are installed with adequate access via inspection chambers and manholes for future maintenance of the system. Package pumping stations transfer sewage effluent form low-lying areas of the site and sewage storage can be provided to control the rates of flow through sewage treatment plants.

Sewage treatment plants

It is not always possible to connect a sewerage system to the public sewer. In these instances septic tanks, cesspools or sewage treatment plants may be used to dispose of sewage effluent. Satisfactory performance of the treatment system used depends upon design, installation, maintenance and mode of operation. We advise upon the most appropriate system to be used where a connection to the main sewer is not available; and provide comparative costs of systems from the major industry suppliers to determine the most cost-effective solution for you.

Disposing of treated effluent

In determining the means of disposing of the effluent our designers will consider the proximity of water-courses and the characteristics of the local geology, performing percolation tests if necessary. Partially treated effluent may be discharged to a drainage field, drainage mound, or constructed wetland. Treated effluent may be discharged to a water-course. Our system designers will recommend the appropriate disposal regime.

Performance of treatment plants

Responsibilities for the performance of the plant lay with the owner of the installation, who must prevent and resolve problems associated with pollution, nuisance and health hazard. Statutory controls include the planning process, building control, environmental health legislation, and regulation by the Environment Agency (EA). As a pre-cursor to the installation process we make applications to the appropriate agencies on our client's behalf to secure the necessary approvals.


In England and Wales discharges to surface and ground waters are controlled by the EA. The Agency has some discretion regarding the mechanism for control of discharges to underground strata or land. The EA always seeks to control discharges exceeding 5m³/day, by means of discharge consent. Where the discharge is to a watercourse, land drainage consent may also be required. Our services include application for all of the necessary consents associated with the private treatment of sewage.