This paper presents a conceptual accounting framework to quantify the life cycle energy use and GHG emissions of alternative urban water supply strategies. The framework enables the comparative analysis of alternative strategies to design a fit-for-purpose water supply system that takes into account water supply, energy use and GHG emissions and has been tested on the Fisherman’s Bend development site in Melbourne Metropolitan region and results are presented. This study does not include the environmental and social benefits incurred from deploying multiple water sources, which must be considered before making strategic decision about implementation of alternative sources of water supply.