It is well known that water is the primary and very indispensable sources for all life existed on the earth including human beings, and the contamination of water by heavy metals and other contaminants can cause detrimental health effects especially for human beings. Currently, the effect of heavy metal pollution on human beings is becoming critical. Heavy metals can cause lethal health effects with various diseases, depending on the nature and quantity of metal, through ingestion, dermal contact, and inhalation pathways. Heavy metals present at even low concentrations in drinking water can be harmful to humans. In countries like Ethiopia with population having low percentage of access to safe water and sanitation more percentage of the population suffers from waterborne and water related diseases. For these facts, evaluation of the physico-chemical and microbial quality of drinking water prior to supply to the consumer is crucial in achieving the well-being of humans. Above the standard limits the Trace elements like (Fe, Zn, Cu, Mn, Ni, and Cr) and Heavy metals (Cd, Co, Pb…) can easily pose a significant health risk on population. Therefore, this study was primarily aimed to evaluate the physico- chemical and microbial quality of drinking water supplied to Addis Ababa city from Legedadi and Geferssa after treatments, reservoirs, and household taps by examining water quality parameters. In this study, a total of 21 water quality parameters are used such as electrical conductivity, turbidity, pH, lead (Pb), Ammonia, Chloride, Chlorine, Fluoride, Nitrate, Phosphate, potassium, Sodium, Total Hardness, Total alkalinity, Turbidity, aerobic plate count, total coli form, fecal coli form and E-coli, Free Residual Chlorine. According to (WHO, 2020) standard with compered that the results of the parameters were used during both dry and wet seasons. The result of water quality parameters for both seasons after treatment at reservoirs and household taps indicated the concentration of aerobic plate count, total coli-form, fecal coli form, chlorine, phosphate, potassium, Iron, Mn were all above the drinking water standard limit while all others were within the standard. Therefore, it can be concluded that along distribution system (but not for all parameters), the drinking water was subjected to contamination and the water quality decline. On the side of microbial results; the drinking water showed fecal source of contamination.it should be recommended that human and livestock intrusion to the upper catchment agriculture activity, treatment efficiency, waste disposal and wastes management system should be seriously considered and properly handled to protect from pollution. xii Key words: parameters, water sanitation, Drinking water quality, household tap, distribution system