The report shows projections of future demands for water in all of the regions, for all purposes, and relates them to present supplies and supplies that can potentially be developed by storage. Basic water problems are related to provision of the proper quantity and quality of water in places needed at the times needed. The report therefore deals with the basic physical problems of providing necessary facilities for storage and treatment of water, quantity being controlled by storage and quality being controlled by treatment. The report develops relationships between the amount of treatment and the storage required to meet needs in 1980 and 2000, and lays out several broad potential programs for meeting the Nation's needs through either a minimum storage program, a minimum treatment program, or through a minimum economic cost program.