Abstract: A method for purifying a flow of water, by eliminating any Legionella bacteria present therein using (a) an ozone generator, (b) an ozone injector for injecting ozone into the flow of water, (c) a mixing chamber for mixing the ozone with the flow of water; (d) an outlet for the flow of water, and (e) an electronic controller for the operation thereof: wherein the mixing chamber is of an inner geometry such as to create turbulence in the flow of water therein.