Abstract: The present invention concerns a method for reducing the amount of polluting and/or valuable elements through application of electrolysis, in particular of the electrocapturing phenomenon. The electrolysis according to the present invention is applied permanently over time in a polluted water body. The predetermined action area (115bis, 115ter) preferably has a smaller extension than the water body. The at least one phenomenon (125bis, 125ter) is preferably powered electrically through production of electrical energy in loco through at least one renewable energy source (140). The method is suitable for purifying large expanses of water, like seas, lakes, lagoons and rivers, through plants operating permanently, however this does not rule out other applications.