This dataset represents the average level of conventional treatment at tap water plants in Inner Mongolia, covering the entire production process of tap water from raw water intake to plant effluent, specifically including conventional treatment units such as water intake, coagulation and sedimentation, filtration, disinfection, water storage and water conveyance. The dataset focuses on recording the use of agents such as coagulants, disinfectants and sludge treatment agents, as well as related contents such as electricity consumption and water plant construction and maintenance. The data are derived from statistical yearbooks.