The present study deals with the physicochemical characterization of the water quality of the Drader River, Main River of the Drader-Souier basin. This work done on the Drader River is original, since no study of the physico-chemistry of Drader river waters had been done before, it contributes to a better knowledge of the watercourses of the Drader - Souier basins. This study involved three (3) stations on the Drader riverbed from upstream to downstream, with a frequency of biweekly water withdrawals. We analyzed nineteen (19) physico-chemical parameters (temperature, pH, conductivity, salinity, sodium, potassium, calcium, magnesium, chlorides, sulphates, bicarbonates, orthophosphates, nitrates, nitrites, ammonium, biological oxygen demand, demand chemical oxygen, suspended solids and dissolved oxygen). The results obtained show that the water upstream of the watercourse is an excellent quality against downstream, the water has undergone a slight degradation which can be explained by the intense agricultural activity and possible contamination in the water. Level of station 2 by domestic discharges.