With increasing importance of global-scale environmental issues in addition to regional environmental issues, an analysis of life-cycle environmental impacts becomes essential to the management of basin-scale artificial water use systems. In this study, we evaluate the life-cycle environmental impacts, i.e., global warming potential, acidification potential, eutrophication potential, mineral and fossil resource consumption and induced water resource consumption, of the water and sewage systems in Saitama prefecture and Tokyo's special city wards including advanced treatment and reclaimed water use, in consideration of their construction, operation, and dismantling of such systems. The results indicate that the induced impacts increase with the introduction of advanced water and sewage treatment, and that such impacts are mitigated by substituting reclaimed water for conventional tap water dedicated to flush water and general service water. The net induced impacts except mineral and water resource consumption increase in those scenarios where advanced treatment and reclaimed water use are introduced, while direct water intake and water pollutant emissions are reduced.