Abstract: It is crucial to explore sustainable approaches for the coordinated development of water pollution and economic growth at the city level. Based on annual data on water pollution concentration and GDP from 287 cities of China between 2012 and 2022, a dynamic panel effect model is constructed to investigate changes in five major water pollutants: COD_Mn, NH₃-N, COD, TN and TP and analyze the relationship between water pollutants and economic development. Additionally, this paper explores the differences in EKC patterns in different cities and the effects of water regulation intensity and per capita income levels on the formation of EKC inflection points. The findings reveal the following: (1) The COD_Mn, NH₃-N, COD and TP of 287 cities in China between 2012 and 2022 show a decreasing trend, while TN fluctuates. (2) Except for COD, there is an inverted U-shaped relationship between COD_Mn, NH₃-N, TN and TP and economic development. (3) Heterogeneity results indicate that cities east of the Heihe-Tengchong Line and the non-resource-based cities show a significant inverted U-shape relationship. (4) Investigation into factors influencing the inflection point formation reveals that most cities with an inverted U-shaped relationship between water pollutants and economic development are those with high water regulation intensity and high residents income levels. It is recommended to strengthen prevention and treatment of COD pollution, transform the traditional economic development model in cities west of the Heihe-Tengchong Line and resource-based cities, emphasize water pollution prevention and treatment, and engage residents in water environment improvement.