PHYSICOCHEMICAL AND MICROBIAL QUALITY OF DRINKING WATER IN ADDIS ABABA CITY, ETHIOPIA

Abstract

Water quality is one of the basic requirements for human health, development and wellbeing. The study was conducted from December 2021 to March 2022 to determine the physicochemical and microbial quality of drinking water in Addis Ababa city. A total of 1353 water samples were collected from eleven sub city drinking-water sources in three rounds such as 825 from tap water, 132 from well water, and 396 from reservoirs water sources. All the collected data were processed and compared against standards set by the World Health Organization and Ethiopia Standard Authority. The bacteriological analysis confirmed that some of the water samples in the study area had total coliforms, faecal coliforms, and aerobic mesophilic bacteria. The mean counts of aerobic mesophilic bacteria count, total coliforms count, and faecal coliform count ranged from 0.58-4.35 colony forming unit/100 ml, 0.5-4.33 colony forming unit/100 ml, and 0.33-1.43 colony forming unit/100 ml respectively. The water samples were also analyzed for the presence of Entoamoeba histolytica, Giardia, Cryptosporidium, yeasts and moulds. In addition, the physico-chemical parameters such as pH, electrical conductivity, total hardness, fluorides, iron, and manganese contents of the drinking water were evaluated. With respect to parasitological analysis, all water samples examined were negative for Entoamoeba histolytica, Giardia lamblia, and Cryptosporidium parvum cysts. The mean yeast and mould counts were also ranging from 1.36-2 colony forming unit/100 ml, and 1.66-3 colony forming unit/100 ml respectively. In this study residual free chlorine has a negative correlation with TC, FC but pH has a negative correlation with TC, FC. This study revealed that all water samples analyzed for microbial did not meet the acceptable bacteriological limits of safe drinking water set by the World Health Organization and Ethiopian Standards Authority guidelines but physico-chemical parameters were within the range of recommended guidelines. Finally, recommendation is made to responsible authorities of the Addis Ababa Water Sewerage Authority to implement effective water treatment methods to produce microbiologically safe drinking water in area.