Water treatment is, collectively, the industrial-scale processes that make water more acceptable for an end-use, which may be drinking, industry, or medicine. Water treatment should remove existing water contaminants or reduce their concentration to the extent that water becomes fit for various uses.

The processes involved in treating water for drinking purposes to provide a safe source of water supply may be solids separation using physical processes such as settling and filtration, chemical processes such as disinfection and coagulation.