In the face of increasing global challenges, such as water scarcity, population growth, and environmental degradation, sustainable management of water resources and wastewater treatment is a major concern. However, sometimes missed regarding the potential impact of water system management on the environmental implications contained in the production process of water and waste treatment systems. This study sought to assess the environmental efficacy of an integrated water supply and wastewater system in Semarang City. The secondary objectives of the study were to ascertain the extent to which each stage of the system contributed to the impact categories that were analyzed. Life cycle assessment is a method to evaluation of the environmental impacts associated with water resource and wastewater management, using 1 m3 as functional unit. The stages of water use are not examined in this study. Another restriction is the absence of information about the city's untreated wastewater quantities' final destination. Water treatment plant include water withdrawal and water distribution are most impacted under the climate change environmental impact category and other impact that assess until 99%. In seven of the eight impact categories examined, power consumption is the most impactful input.