Abstract: A purifying method for photochemical elimination of xenobiotics present in water. The purifying device is used which has a photochemical reactor unit having at least one inlet for contaminated water and one outlet for purified water, it provides a flow path for continuously flowing water from said inlet to said outlet, and is equipped with a radiation source module providing ultraviolet radiation in a wavelength range ranging from 100 to 280 nm. The method includes performing ultrafiltration, thereby removing suspended and solvated macromolecular matter from the water; conducting the permeate via the at least one inlet into the photochemical reactor unit; subjecting the water flowing from said inlet to said outlet to ultraviolet radiation at wavelengths ranging from 100 to 280 nm, thereby generating hydroxyl radicals initiating degradation of said xenobiotics; and supplying air or dioxygen into the water, thereby enhancing the initiated oxidative degradation of said xenobiotics.