This study was carried at out four main centers in Qalyubia Governorate, Egypt namely Benha, Kafr Shukr, Toukh and  Qalyub before and  after treatment process of  drinking water. Each of  the four main sites included subsites along the distribution system namely Benha (Mit Asem and  Benha), Kafr Shukr (Isnit and  Kafr Shukr), Toukh (Toukh, Al Deir and  Qaha), Qalyub (Qalama and Qalyub). Physical and  bacteriological examinations were carried out in both main and  subsites during winter and  summer 2017-2016. Turbidity and   pH values were ranged between (1.16-2.60) NTU  and (7.27-7.87) during two seasons after treatment process, respectively. Additionally, lower values of electric conductivity (EC) and Total hardness (T.H.) were recorded after treatment than  and before, the lowest values were observed in Qalyub and Benha during summer, respectively. Moreover, total solids (dissolved TDS and suspended TSS) values were in permissible limits  and indicate the efficiency of treatment process. Respecting the changes in total bacterial counts in all main subsites under study, higher counts bacteria were observed in samples incubated 37℃ than 22℃ with highest count in Qalyub and  Toukh, respectively. While Salmonella and  fecal streptococci counts were reduced with considerable numbers after treatment than before and most of subsites didn't record any counts  of Salmonella during winter. The most prevalence bacteria were isolated and testing of their susceptibility agains  antibiotics and found one  of them was multiple antibiotics resistant which finally identified by 16sDNA genev sequencing as Salmonella enterica. Various chlorine concentrations found to be efficient against S. enterica 7.0 ppm was the best with save residual chlorine concentration.