The lack of fresh water is one of the major threats for people. The extremely sufficient and cost saving methods for water and wastewater treatment must be applied. The paper shows possibility of using traditional Dissolved Air Flotation method (DAF) with alternation of feeding gas by ozone (Dissolved Ozone Flotation - DOF) instead of air to obtain better treatment results and possibilities of decreasing the costs of water and wastewater treatment. Moreover the DOF method may come in effective in case of more and more restrictive recommendations regarding water quality and micro-pollutants removal. As the method is on early stage of the research many technical aspects and mechanisms must be taken into consideration and to be investigated. Presumably the DOF method could be applied in technical scale for pre-treatment of industrial wastewaters, fracturing fluids, water with algae or for final separation of effluent and excess sludge in municipal wastewater treatment plants.