The study aimed to determine the seasonal changes and the distribution of some fecal indicator bacteria and coliphages in inlet and outlet groundwater samples that used as drinking water in Zagazig city. The samples were taken two times every month for 12 months in triplicates from all selected six wells (El-Zeraa, El-Sagha, Wapour El-Nour, Abo-Aamer, El-Hesania and Gamal Abd El-Naser wells). The inlet and outlet groundwater samples of wells tested during one year period were clostridia free. Higher Salmonella and Shigella positive percentage was recorded in El-Zeraa (58.3%) and El-Sagha (50%) wells in inlet samples. While Wapour El-Nour and Abo-Aamer wells were Salmonella and Shigella free. The inlet groundwater samples of all six tested wells were Aeromonas spp. free, except El-Sagha well where the positive percentage reached 25.0%. The range of coliphages density during three months was from zero to 5.1 x 10³ PFU/100 ml^-1 inlet and from zero to 6.1 × 10³ PFU/100 ml^{-1 in outlet samples. The results revealed that the coliphage counts increased in the water samples as the increasing of the environmental temperature. The relationship between total coliform/coliphage, fecal coliform/coliphage and fecal streptococci/coliphage in inlet groundwater samples of the same site were 1:3.39, 1: 4.47 and 1:3.24, respectively. Significant and positive correlation coefficients were observed between coliphage versus total coliforms (0.931 and 0.999), fecal coliform (0.609 and 0.769) and fecal streptococci (0.959 and 0.961), in inlet and outlet groundwater samples of El-Zeraa well, respectively. From the obtained results and the hygienic point of view, groundwater should be correctly chemically treated before its distribution for drinking.}