The Banger River, bordered by settlements, industrial sites, and agricultural land, has faced critical pollution challenges due to waste generated by surrounding activities. This contamination has led to a significant decline in both the quality and quantity of available clean water, a situation further exacerbated by rapid population growth. For years, the presence and severity of fecal pollution in natural water bodies have been monitored through the measurement of coliform bacteria, serving as a vital indicator. In this study, numerical simulation models were utilized to assess the distribution of total coliforms in the waters of Pekalongan. The findings indicated that the distribution of total coliforms was significantly affected by tidal currents, which predominantly flowed westward along the coastline. The coliforms were sourced from various runoff pathways throughout the Banger River, with concentrations increasing up to 65,693 CFU/mL as one moves further west. In the coastal area of Pekalongan, coliform concentrations range between 15,252 and 62,332 CFU/mL. These results underscore the urgent need for effective water management strategies to mitigate fecal contamination and protect public health in the region.