This dataset represents the average level of advanced treatment at Liaoning water treatment plants, covering the full production chain of tap water from raw-water intake to plant effluent, specifically including conventional treatment units such as water intake, coagulation–sedimentation, filtration, disinfection, water storage and water conveyance, and also covering advanced treatment stages such as activated carbon adsorption, ozone oxidation and membrane filtration. The dataset focuses on recording the use of chemicals such as coagulants, disinfectants and sludge-treatment agents, as well as electricity consumption, water-plant construction and maintenance, and other related items. The data are sourced from statistical yearbooks.