Introduction: Globally, drinking water quality is continuously deteriorating and becomingrnnon-suitable for human use and well-being. That is why, above 20% of the world, populationrndoes not have access to pure drinking water. Globally, 26% of people drink water that is, atrnleast occasionally, contaminated with fecal bacteria. Of all human illnesses in the developingrnworld, 80% are caused by biological contamination. Further, more than 33.3% of the worldrnpopulation does not have access to improved sanitation. Globally, the health burden of poorrnwater quality, sanitation and hygiene is massive. Despite advancements in food science andrntechnology, food and waterborne disease remains one of the major public health problems inrnthe world. In many parts of low-income countries such as in Ethiopia, public health problemsrnassociated with deterioration of food and water safety situations are much more aggravatedrndue to poverty and environmental related risks. Data from the previous studies indicated thatrnseveral food establishments in Addis Ababa lack safe drinking water and suffer from poorrnsanitation and hygiene practices. Credible evidence from scientific literature substantiate thatrninadequate sanitation and poor hygiene conditions of food establishments are the major causernfor the occurrence of food and water borne diseases. In such case, there is huge demand forrngood sanitation practice and proper handling of drinking water in the food establishments. Inrnmy view, this is the frame in which I derive the objectives for my PhD work, basically torninvestigate microbial drinking water quality, sanitation and hygiene situation of foodrnestablishments as well as health status of food handlers in Addis Ababa.rnMethods: Institution based longitudinal and cross-sectional studies were conducted. Samplernsizes were calculated using a single and two population proportion formulas. Stratified,rnsimple random sampling techniques were employed. For this study, 250 drinking waterrnsamples, 420 food establishments and 420 food handlers were included to assess drinkingrnwater quality, sanitation and hygiene status of food establishments, awareness, outlook andrnpractice of food handlers respectively. Moreover, 1058 food handlers were included torndetermine diarrheal disease and associated behavioral factors among food handlers. Data wasrnanalyzed by SPSS version 20. A repeatedâ€“measure ANOVA, Binary Logistic Regression,rnMultivariable Logistic Regression and Linear Regression Model and analysis of variancernwere used for data analysis.rnxivrnResults: The longitudinal data analysis indicated that, 26.4% and 10.7% of the foodrnestablishments drinking water had occurrence of Escherichia coli type of bacteria in the wetrnand dry season respectively. The finding of the study revealed that, 3.2% and 1.6% of thernfood establishments drinking water had very high health risk to customers during the wet andrndry season respectively. In the study, the mean score of fecal coli forms count pre100/mlrnwere found to be 7.59 and 3.12 in the wet and dry season respectively. There was statisticallyrnsignificant difference between the mean values of the E. coli per 100ml between the dry andrnwet season with P-value