Sewage treatment is the process of removing contaminants from wastewater, primarily from household sewage as well as runoff from rain and groundwater that may contain harmful bacteria and other contaminants. The goal of sewage treatment is to produce an effluent that is safe to discharge back into the environment.
The level of cleanliness of water after sewage treatment varies depending on the treatment process used. Primary treatment removes solids and organic matter, while secondary treatment further removes bacteria and other contaminants. In some instances, a third stage of treatment known as tertiary treatment may be employed to remove additional contaminants and produce water that is suitable for reuse.
Treated water is typically safe to discharge back into the environment, as it meets certain standards for water quality. However, it is not recommended to drink or bathe in treated water without further purification.