This chapter discusses the types and sources of common water pollutants, how they are used, and how they subsequently impact drinking water resources, their drinking water standards, and their treatment methods. This knowledge is necessary for environmental professionals to conduct site assessment and remediation work. Common organic contaminants found in drinking water include chlorinated hydrocarbons, such as Trichloroethylene (TCE) and perchloroethylene and non-chlorinated hydrocarbons associated with petroleum fuel products, such as benzene and methyl tertiary butyl ether (MTBE). The fuel oxygenate MTBE has been used extensively as an additive in gasoline to reduce air pollution and to enhance octane ratings. TCE is a volatile, colorless, chlorinated hydrocarbon compound that has been widely used as an industrial solvent, primarily for the vapor degreasing and cold cleaning of fabricated metal parts. Arsenic is a naturally occurring element in the earth's crust and is very widely distributed in the environment. Lead and copper are rarely present in raw water sources.