In areas where no foul sewer is available, one option may be the installation of a septic tank. These are usually a two or three chamber system that holds sewage to allow the solids to form a sludge at the bottom of the tank. This system provides settlement and some biological treatment. Usually the remaining effluent liquid drains to a purpose built subsurface irrigation area (soakaway).
Before constructing soakaways it is important to follow guidance in BS6297:1983. Further (tertiary) treatment will be required to discharge to a watercourse such as reed bed systems and water stabilisation ponds. Septic tank systems may need to be regulated by the Environment Agency or ring 03708 506 506 and may also require Planning and Building Regulation consent email@example.com