Life cycle assessment of water supply in Singapore - A water-scarce urban city with multiple water sources

Water scarcity in Singapore has resulted in a complex urban water system with multiple water sources, advanced treatment processes, and recycling for potable and non-potable reuse. While industries are encouraged to reuse and recycle water, the environmental impact of doing so as compared to using public water supply should be considered. However, there is a lack of studies quantifying the environmental impact of water from a complex urban water system like Singapore's. In this study, Life Cycle Assessment (LCA) was adopted to study the environmental impact of Singapore's public water supply, which consists of NEWater (highly purified recycled water) and tap water, to inform industries and policy makers of the environmental impact of these water supplies. Individual components in Singapore's urban water system were studied and their results combined to develop the LCA of NEWater and tap water. The results show that 1 m(3) of "NEWater at consumer" and 1 m(3) of "tap water at consumer" contributes 2.19 kg CO2-Eq and 1.30 kg CO2-Eq to climate change potential, and 0.00344 m(3) and 0.882 m(3) to water depletion potential respectively. The results indicate the importance of including CH4 , N2O, and NOx emissions in wastewater and urban water system-related LCA studies.