This unit reviews the demand for potable water and the nature and characteristics of available water sources and drinking water treatment technologies. The physical, chemical and biological quality of different water sources are considered together with a detailed review of the various water treatment processes that can be applied to produce potable water from them, including screening, clarification [coagulation/flocculation], sedimentation/floatation, filtration, disinfection, adsorption, ion exchange and use of GAC/PAC and fluoridation. Water distribution and supply is reviewed together with the safeguards that are taken to protect consumers, with an emphasis on disinfection. The relevant drinking, bottled and private water supply legislative and regulatory framework is also covered within the unit.