Water treatment systems are used to clean drinking water and process wastewater to help prevent the spread of disease. Drinking water can be treated at the source, at the distribution point of houses or spickets, or at a central processing plant before being distributed to customers.

Water treatment requires chemical, physical, and sometimes biological processes to remove contaminants. The more common processes used in potable water treatment are the chemical and physical processes. Biological processes are primarily used for treatment of wastewater.