Sewage treatment is the physical, chemical or biological process of removing contaminants from wastewater or sewage. This can be required for domestic, agricultural or commercial properties. The objective is to produce an environmentally safe fluid.
The majority of houses in the UK are linked to the public sewerage system. You pull the plug, flush the toilet, pay the monthly bill and have little more to worry about. This is known as mains drainage.
In rural areas many homes and villages are self-contained. Either a cesspool, septic tank or sewage treatment plant will be used. This has no connection to the public sewerage system and is known as off-mains drainage.