Ensuring safe surface water management is crucial to meet global drinking water standards. Thus, this study was conducted to evaluate the water quality of some drinking water treatment plants in Damietta governorate, including the inlet fresh water of the Nile River and the outlet drinking water. Water samples were collected from 11 treatment plants located at the River Nile, and the physicochemical parameters, in addition to some heavy metals, were analyzed seasonally through the year 2022.  Water quality and heavy metal pollution indices were employed to assess the status of water quality. A One-way Analysis of Variance (One-way ANOVA) was applied to compare the spatial and temporal variation of the Water Quality Index (WQI). The results illustrated that the average value of turbidity, pH, Electrical Conductivity (EC), Total Hardness and Total Dissolved Solid (TDS) of plant inlets was 3.37 NTU, 8.05, 359.3 µmohs/cm, 162.6 and 188.9 mg/l, respectively. Besides, chloride, sulphate, calcium, magnesium, iron, lead, cadmium, and zinc concentrations were 24.6, 28.5, 10.9, 6.2, 0.04, 0.029, 0.006, and 0.15 mg/l, respectively, whereas plant outlet results indicated that the average value of turbidity pH, EC, TDS, and Total Hardness was 0.61 NTU, 7.51, 372.7 µmohs/cm, 155.8, and 201.2 mg/l, respectively. The concentrations of chloride, sulphate, calcium, magnesium, iron, lead, cadmium and zinc were 30.4, 33.4, 37.9, 16.8, 0.02, 0.01, 0.003 and 0.065 mg/l, respectively. In conclusion, all the investigated parameters were within the permissible limits according to WHO (2017), except lead and cadmium in plant inlets, which slightly exceeded the standard limit. The Average Water Quality Index values confirmed that Nile River water was good (52.4), while the outlet drinking water quality was excellent (45.5).