In this research paper, the problem of studying the effectiveness of ozone in the process of water treatment is considered. In the course of the scientific work, a review of domestic and foreign literature was conducted, its advantages and disadvantages were considered. The research paper presents theoretical and practical methods of water purification with ozone. The main factors influencing the efficiency of the technology in the process of water purification are also considered. It is established that as a technological method of water purification, the efficiency of the ozonation process includes not only the cost of electricity, but also the efficiency of its mixing, ozone dissolution in treated water. In addition, special attention is paid to the final stage of mixing the ozone-air mixture with treated water. From the results obtained, it can be seen that after primary ozonation, the concentrations of chromium, oxidation of permanganate, iron, petroleum products, metal ions and other pollutants significantly decreased. During further water purification, organic and inorganic pollutants are removed in the future (completely or up to the requirements of the standard). However, calcium, magnesium, sulfates, chlorides, pH value, alkalinity and hardness practically do not change. The water quality after primary ozonation according to bacteriological indicators met the requirements of the standard.