The present invention relates to an agent for the preventive and/or curative cleaning of materials in contact with water, characterized in that it includes sodium chloride and at least one dispersant detergent and/or a non-ionic surfactant having at least one detergent action and at least one oxidizing agent, characterized in that the oxidizing agent is selected from solid-form precursors of hydrogen peroxide and in that the cleaning agent is in solid form, such as pellets, granules, bars tablets, large pellets or powder, the salt(s) being used as binders between the various components. Another objective of the present invention is to provide a method for agglomerating the various ingredients according to the present invention, even when they are present in a liquid form. The present invention also relates to the use of the cleaning agent for the preventive and/or curative cleaning of materials in contact with water.