This study, for the first time, investigates the historical changes of the water use in China’s electric power sector on a regional level and quantifies the impacts of four factors that have influenced the remarkable changes: population, power production per capita, power plants’ type and their cooling technology choice. From 2000 to 2015, water withdrawal and consumption in China’s electric power sector, excluding hydropower, have increased from 40.75 and 1.25 billion m3, respectively, to 124.06 and 4.86 billion m3. As population growth in China has stabilized, population no longer provides an upward pressure on power production and the corresponding water use. On the contrary, power production per capita has played the most significant role contributing to 103.40 and 3.84 billion m3 of water withdrawal and consumption increases respectively, though the effect is now leveling off. The electric power sector’s water use would have been much greater had it not been for changes in plant type and cooling water technology. Energy transformation to low-carbon sources has mitigated water withdrawals and consumption by 14.46 and 0.43 billion m3 respectively during the study period. This beneficial reduction in water use is a co-benefit of a series of policies primarily aimed to reduce carbon emissions and other air pollutants. Changing cooling technologies has offset 14.07 and 0.10 billion m3 of water withdrawal and consumption increases nationally, but the effects varied by region.