Public water services encompass the provision of collective services to a given community, typically an urban center. Water supply entails the abstraction of raw water from a natural source, such as surface water (e.g., rivers and lakes) or groundwater (i.e., aquifers); its treatment to make it fit for human consumption; and, finally, its distribution to households and commercial users via an underground pipeline network. This entry discusses public water services as a natural monopoly, the history of public water service organizations in Organisation for Economic Co-operation and Development (OECD) countries, public water services in developing countries, global trends concerning the [Page 2316]public versus private provision of water services, the restructuring of public water operations, and the principles underlying successful public sector reform.