Water treatment is any process that makes water more acceptable for a specific end-use, which may be drinking, industry, irrigation, river flow maintenance, water recreation or many other uses. Water treatment should remove existing water contaminants or so reduce their concentration that their water becomes fit for its desired end-use, which may be safely returning used water to the environment.
Treatment for drinking water production involves the removal of contaminants from raw water to produce water] that is pure enough for human consumption without any short term or long term risk of any adverse health effect. Substances that are removed during the process of drinking water treatment include suspended solids, bacteria, algae, viruses, fungi, and minerals such as iron and manganese. The processes involved in removing the contaminants include physical processes such as settling and filtration, chemical processes such as disinfection and coagulation and biological processes such as slow sand filtration.