The application of this technical knowledge and know-how to produce safe drinking water and make it available to all in the form of community water systems can be a major factor in social and economic development. A water system is a tangible demonstration of accomplishment; it is essential to economic progress. Only a healthy citizenry can reach its maximum potential; and safe water, free of the infective agents of a dozen different diseases, is mandatory if people are to be able to do that and to benefit from a higher living standard.