The objective of the research was to analyze aluminum contamination in the water purification process of the Carrizal River sub-basin and the Municipal Joint Drinking Water Company (EMMAP-EP) of the Tosagua canton, with an exploratory-descriptive approach and eight sampling points were established, aluminum was analyzed in sediments, sludge, and water at different stages of the purification process. the ICP-OES method was used to determine the concentrations of aluminum. Then the mass balance of this element was carried out. The results showed aluminum concentrations at different stages of the process, with the highest concentration in the settling of sludge for both sediments (10902.93 mg/kg) and water (0.896 mg/L). In comparison, the reservoir and the river presented similar concentrations for sediments (9329.75 mg/kg and 9344.46 mg/kg) and water (0.736 mg/L and 0.662 mg/L). While in the distribution networks, a concentration of less than 0.17 mg/L was evidenced, which is below the limits proposed by the WHO and the EPA, while the mass balance revealed a net accumulation of 42.16 g/day of aluminum, indicating that the system retains this element.