The rapid growth of the population in Egypt has made an impact on the portable water demand, which requires exploration of raw water sources, developing treatment and distribution systems. The Ismailia canal represents the most distal downstream of the main Nile River. Thus, its water contains all the proceeded pollutants discharged into the Nile. However, the water treatment plants system along this canal must be modified before application. However, this research is being conducted at two surface water treatment plants (Al- Amerya and Mostorud) along the canal. In that manner, to reduce treatment chemical estimation error and consequence obtain the optimal treatment efficiency, this study aims to model the appropriate amount of alum used for the coagulation process taking into consideration the canal surface water quality characteristics. Meanwhile, a predictive nonlinear model for determining the required aluminum sulphate (alum) quantity for studied water treatment plants (WTPs) was developed by considering the interrelationship between canal water quality parameters such as Temperature, pH, Turbidity, and the quantity of Alum required for the mentioned drinking water treatment plants. The model constants were obtained using a least square regression method. Then, many alternative models were developed for quantifying the required alum dosage based on the dominant surface water quality parameters. Comparison of the model simulation with the experimental data showed a good prediction. The study revealed that the optimal coagulant dosing can be predicted from the operating data with accuracy to reduce the number of chemicals being used.