Evaluation of carbon emission hot spots for water treatment plants (WTPs) is crucial to reduce carbon emissions. This study aims to analyze carbon emission data generated at Bansin WTP following the PAS 2050 guidelines. The boundary of inventory and assessment includes water intake, purification, and distribution stages. In addition, pumping efficiency, power consumption per pump lift and specific energy consumption were used to estimate the potential of energy reduction in pumping for Bansin and Baoshan WTPs. The results have revealed that the carbon footprint of Bansin WTP is 0.39 kg CO2e/m3 in 2011. There is 95% of carbon emissions generated by pumping from the intake and distribution stages, and the use of pumping is responsible for 65% of total carbon emissions in the clarification stage. The power consumption per pump lift can be calculated to evaluate the difference between rated power and operational power. This relationship can provide information indicating to operators when to replace or maintain poorly-functioning pumps. The data on pump lift, flow rate and power can also be calculated to determine the relationship between pumping efficiency (%) and specific energy consumption (kW/Q), and then used to identify the optimum condition of pump combinations for a given production of water supply.