Water supplied to consumers must meet safety standards and be free of pathogens and hazardous materials. Thus, this study aims to evaluate the efficiency of disinfectant process and microbial control for some drinking water treatment facilities. Water samples were collected from eleven treatment plants at River Nile. The investigation based on bacteriological analysis of two sampling point for each plant, the source catchment (inlet) and produced water (outlet). The subjected analysis included total plate count (TPC) using pour plate method, total coliform (TC), fecal coliform (FC) and fecal streptococcus (FS) which conducted by membrane filtration. The result showed that the mean value of total plate count, total coliform, fecal coliform and fecal streptococcus of plant inlets were 301.4±138.1, 152.3±95.4, 28 ± 12, 33 ± 10.7 CFU/100ml, respectively, while for plant outlets were <1 in all parameters except total plate count which was 24.72±6.47 CFU/100ml. It was indicated that the fecal coliform and fecal streptococcus of plant inlets and outlets was within the permissible limit according to WHO standard but total plate count and total coliform exceeded the standard limit in most plant inlets. According to the results of the examined River Nile water samples, there was microbial contamination in catchment point of each station. However, drinking water treatment plants efficiency for the investigated biological parameters varied between 88% and 100%. In conclusion, it's recommended to perform a temporal and spatial assessment of Nile River at consistent intervals to mitigate the potential impacts and sustain the main drinking water source.