Drinking water quality is one of the most important components of public health and sustainable water resource management, and its continuous assessment, especially in urban areas, is of particular importance. In this study, the quality of drinking water wells in Mahmoudabad County was evaluated using the Water Quality Index (WQI) and the National Sanitation Foundation Water Quality Index (NSFWQI). The dataset included physical and chemical parameters such as pH, nitrate, total hardness, chloride, sulfate, total dissolved solids, turbidity, and temperature during the period 2020–2025. To achieve a more comprehensive evaluation, in addition to calculating water quality indices, Pearson correlation analysis was applied to examine the relationships among parameters, and the k-means clustering method was used to classify samples into groups with similar quality characteristics. The results indicated that the general water quality in most urban wells of Mahmoudabad ranged from good to excellent; however, in some samples higher index values reflected a relative decline in water quality and the sensitivity of groundwater resources to land-use changes and agricultural activities. Correlation analysis revealed consistent behavior among parameters such as total hardness, sulfate, and total dissolved solids, as well as the significant role of nitrate in reducing water quality. Furthermore, clustering analysis highlighted the spatial variability of water quality and the influence of hydrogeological conditions and human activities. The findings of this study demonstrate the effectiveness of a multidimensional approach for monitoring, management, and targeted planning of urban drinking water resources.