water supply system, carbon footprinting, input output life cycle assessment, process life cycle assessment
This study aims to calculate the carbon footprints of two water supply systems in Taiwan, one is a traditional water treatment plant (FYWTP) and another is a seawater desalination plant (KSDP) and each with different characteristics in terms of topography, scale, raw water quality, and purification process. The scope of inventory and assessment includes the intake, the purification, and the distribution stages, as well as the infrastructure and the chemicals used that are associated with these stages. Carbon footprints are calculated based on the unit water sold (m3). The calculation is performed in accordance with the Life Cycle Assessment (LCA) methods of Process LCA (PLCA) and Input Output LCA (IOLCA). It is shown that carbon footprints for FYWTP and KSDP from the PLCA are 9.6305 and 0.1942, while from IOLCA are 7.4692 and 0.0591 kgCO2eq/m3, respectively. The discrepancy of the results will be discussed in the paper together with some suggestions for the future study.