Surface water treatment plants use iron alum to remove suspended particles like clay and bacteria. A study at a plant in Dong Nai River found that the amount of alum needed depends on raw water turbidity and season. By analyzing data and conducting Jar tests, researchers determined the appropriate alum dosage for effective coagulation and flocculation. Linear regression analysis showed that raw water turbidity and season explain 78% of the differences in alum dosage needed for treatment. This research helps ensure proper water quality and efficient operation of treatment plants.