Ozone for water disinfection and chlorine have very similar disinfectant properties. However, their uses today differ due to the environmental consciousness of our society. The aim of this study was to improve disinfection techniques by using ozone. For this purpose, Raw water samples collected from the Nile River (Damietta Branch) near conventional Water Treatment Plant (WTPs) in Daqahliya Governorate. Microbiological examinations include: Total plate count, total coliform, fecal, algal count, and microscopic examination. Also, disinfection by ozone and chlorine were studied. As a result, ozone can be used as a disinfectant for Nile water instead of chlorine, where the optimum dose used was 10 mg/l higher than that used in the case of chlorine 4.6 mg/l. The concentration of ozone and chlorine were under permissible limits according to the Egyptian standards for drinking water (2007). The current work was shown to monitor TBC, TCs, FCs, and non-FCs by removal percentage reaching to 99.87, 99.97, 99.96, and 99.02% for each, respectively, for chlorine. While with ozone the removal percentage reaching to 99.9, 99.95, 99.93, and 98.92%, respectively. On the other hand, the ozone algal counting analysis revealed that, total algae, green algae, blue green algae, and diatoms with removal efficiencies of 91.07, 90.24, 100, and 88.24%, respectively, chlorine counting analysis show removal efficiencies of 94.42, 95.08, 100, and 91.62%, respectively. It's concluded that using ozone is one of the future ways to meet the environmental water standards and supply the water requirements of the growing population.