The definition of sewage (wastewater) is both grey water which is water used in private houses from toilets, dishwashers, sinks, baths and showers and black water which is any water from toilets. This foul water can be treated by using either biological matter to break down the waste or physical treatment using aeration to treat the water.
If your property is not connected to the main sewer network, then you will need to install some form of sewage treatment system to process the wastewater into a form that can be safely drained into your local water course or can be discharged into a soakaway.
The solution to treating waste on site, which is becoming more common, is a sewage treatment plant. As the name suggests, a sewage treatment plant will treat the incoming waste from a property, to a point where it can safely re-enter the water cycle without causing damage to the local environment or eco-system.
