Municipal water requirements are directly related to population whereas industrial demands are related to the level and type of industrial activity. The emphasis on domestic energy production will exert a strong influence on future industrial water demands. The most critical water using regions for mining will be the western regions. Anticipated conservation measures will have a significant impact on water savings in the industrial sector where much conservation can be expected through process changes, recirculation, and several emerging technologies. Water utility planners who forecast the raw water storage volume need to consider the combined effects of anticipated population rise, industrial mix and its likely growth, and the probable savings due to conservation. The material presents some guidelines together with regional tables in an attempt to provide a framework to aid in the estimation of the present and future municipal and industrial water requirements in the western United States.