Information about the relationship between water and health is provided in this module. Topics considered include: (1) the various uses of water; (2) water demand of individuals in certain communities; (3) water sources; (4) water cycle; (5) pure water; (6) water pollution, focusing on pollution resulting from heat, chemicals, radioactive materials, oils (and suspended solids and colloids), and pathogenic organisms (bacteria, viruses, fungi, protozoa, and helminths); (7) water as a factor for the spread of diseases; (8) water-related diseases; and (9) water treatment. Included in appendices are tables with data on selected characteristics of dwelling units and households, water-related diseases (their entry and exit in man), modes by which certain water-borne diseases are spread, number of cases and death by leading diseases, highest number of cases for several diseases in various regions; and morbidity causes and mortality causes. Also included are suggested individual and group activities related to information in the appendices. (JN)