This manual provides information of interest to planners and designers of small water systems. Such systems generally cannot benefit from economies of scale, and proper management and operation are critical to produce satisfactory finished water quality. Therefore, the major emphasis of the manual is on the design of systems that will be effective and reliable, but that require a level of operation and management activity commensurate with their physical size and the available resources. To this end, consideration is given in subsequent chapters to preliminary planning, source selection and development, water quality and quantity requirements, treatment, pumping, storage, and distribution. Throughout the manual an effort is made to focus on requirements and standards, key design elements, and generalized alternative design methods and their applicability. This manual provides guidance and criteria for the design of small water supply, treatment, and distribution systems. For the purpose of this manual, small water systems shall be those having average daily design flow rates of 380,000 liters per day (100,000 gallons per day) or less.