Seasonal variations of selected physico chemical parameters were investigated for three seasons of the year to determine the drinking water quality of Watari reservoir, Kano state, Nigeria, between the months of November February (cold season) March June (dry season) and July September (rainy season). Five stations were chosen on the reservoir at intersect of the adjourning rivers. Treated water was collected from the treatment plant and potable water from the consumer end. pH, temperature, TDS, conductivity, turbidity, total hardness, suspended solids, DO, BOD, Cl, NO2, NO3, COD and PO43 were analyzed using standard procedures. The mean values of these parameters indicate the effectiveness of the treatment process on turbidity, color, suspended solids and NO3.The high values for nitrates observed may be as a result of the use of nitrous based fertilizer in the localities. There is significant variation (P<0.05) between the values of temperature, suspended solids, conductivity, color, nitrate and phosphates observed for the three seasons. The overall quality of Watari reservoir was found to be within the WHO recommended value for drinking water. However, denitrification and nutrient control need to be ensured to halt the impending threat on the reservoir.