Improvement of life style of human beings as well as rapid population growth raises consumption rate of resources and generates large amount of waste and discharge into water bodies. These lead existence of unsafe drinking water and become the main concerns on developing communities including Fogera woreda of Nabega Keble. The existence of water pollutant and effluent from different sites in Fogera woreda of Nabega Keble of Lake Tana increases from time to time. Considering this problem the study on physico-chemical parameter of water quality of Lake Tana around Fogera woreda of Nabega Keble was under taken. During the period from December 2019 to October 2020 at four sample station the physical and chemical parameters such as pH, total dissolved solid, total alkalinity, electrical conductivity, nitrate, sulphate, chloride, fluoride, magnesium, calcium, total hardness and turbidity were investigated by considering rain and dry seasons. All these parameters are common and found in drinking water. But biological analyses are mostly use in waste water treatment. Statistical analyses of correlations between the various physical and chemical parameters of the water were computed. The results of this study revealed that the concentrations of nitrate (57 mg/L) and fluoride (2.2 mg/L) were high in both seasons compared with the recommendation of world health organization. Aluminum sulphate was used as a coagulant to remove nitrate and fluoride from this drinking water. The optimum coagulant dose during treatment process of nitrate and fluoride was 150 mg/L. The removal efficiency of alum reaches 83.91% and 70.52% for nitrate and fluoride respectively at optimum dose and 60-minute settling time.