This document provides officials in developing countries with a manual that can assist in the planning of community piped water supply systems and is intended to be the basis for the preparation of country planning manuals. A checklist for planning and priorities for selection of projects precedes the elaboration of principles for planning. Principles include consideration of health, economic and social benefits; environmental and social constraints; and technical, economic, financial, logistic, institutional, and sociocultural considerations. The use of low-cost indigenous materials, simplicity for easy operation and maintenance, financial and institutional capacity, and community participation are emphasized. Project preparation, including project identification, pre-feasibility studies, monitoring and evaluation and technical planning are described. Technical subjects include water quality, system capacity, selection and development of sources, pumps, transmission lines, distribution networks, and water treatment. Attention is given to operation and maintenance, economic and financial considerations, logistic support, and local institutions, including human resources development.