Abstract: This invention relates to a method and apparatus (10) for purifying water, wherein oxygen is introduced into the water by electrolysis of the water; and the water is treated with at least one ionized transition metal. In a preferred embodiment of the invention, the electrolysis of the water takes place by passing an electric current through paired electrodes (22) made from stainless steel; and the water is treated with ionized silver, copper and zinc produced at silver (16), copper (18) and zinc (20) electrodes that are supplied with electric current. The invention prevents and combats growth of bacteria fungal and viral pathogens in water, and provides a non-toxic and environmentally friendly method of ensuring the public health in both public and private applications.