The water quality and pollution status of the water supply system of the city of Addis Ababa hasrnbeen studied along three main distribution lines representing Gefersa and Legedadi reservoirsrnand the Akaki well field starting from raw water until it reaches the end user (tap water). Thernwater quality parameters considered include physical, chemical and bacteriologicalrncharacteristics. Electrical conductivity, pH, temperature, FCR and turbidity were measured inrnsitu. BOD, COD, TC, FC, Na, K, Ca, Mg, total iron, Mn, NO3rn-, PO4-P, Cl-, HCO3rn-, CO-rn3, SO4rn2-,rnOH- alkalinity and total alkalinity were determined in the laboratory. A total of 69 water samplesrnwere collected for laboratory analysis. In each distribution system samples were collected at fourrnsites (raw water, sample immediately after first treatment, selected site along the distribution linernand finally from end users tap water). The result displays interesting water quality changes alongrnthe distribution line. The reservoir raw water is distinctly different from the groundwater in termsrnof total ionic concentration. The latter has higher ionic concentration and nitrate content. The rawrnwater of Legedadi shows high phosphate content, 416.93 mg/L, probably associated with highrnfertilizer usage in its catchment. The very low phosphate content ranged from 0.61 to 11.43 mg/Lrnin the tap and intermediate reservoir sites indicate the effectiveness of the treatment system withrncoagulation. With regard to bacteriological analysis, the primary data shows that the water is safernfor drinking. However, secondary records show occasional traces of in the piped water probablyrnrelated to the mix of the water with sewerage system in older leaking pipes. The BiologicalrnOxygen Demand and Chemical Oxygen Demand analysis shows that there is some organicrnpollution. The range of free chlorine residue was 0.08 - 0.91 mg/L and this assessment indicatesrnthat the added chlorine is not effective everywhere. This can be seen from the detection of totalrncoliforms in the piped water. The major anion and cation analysis revealed that all the values arernwithin the WHO permissible limit for drinking. However, occasional high total iron may lead inrnfew places to consumer complaints. Calcium and bicarbonate are the main cation and anion,rnrespectively. The three lines studied may not entirely represent the conditions of the AddisrnAbaba water supply system. It is recommended that more water sampling and analysis isrnrequired to have a clear picture and trace the source of specific pollution.rnKey Words: Addis Ababa, pollution, water quality, water treatment