Study on the Actual Situation of Environment Load of Rainwater Utilization Facilities

Abstract

For addressing the drought situation of large cities, rainwater is utilized for toilets, etc. In residential areas, it is already being used for watering and spraying plants using rainwater tanks. For office buildings and the like, rainwater is collected from the rooftop, and stored in the basement and used in 2150 places. Although there have been reports on design methods and processing performance up until now, little research on environmental load has been performed. Therefore, three kinds of flow sheets were selected, and CO₂ emissions for treating rainwater and through replenishing tap water were calculated. It became clear that it is possible to reduce the environmental burden by increasing the water supply substitute rate and selecting proper equipment.