Abstract: The present disclosure relates to a solid and hydrolyzable tablet for treating contaminated water. The tablet comprises at least one an active ingredient chosen from a precipitating agent, alone or in combination with an agglomerating agent. The disclosure also relates to the use of a tablet for treating contaminated water. The disclosure also relates to a method and a device for treating contaminated water. The method comprises placing water laden with contaminant in contact with a precipitating agent and/or an agglomerating agent, dissolving these agents, mixing these dissolved agents with the water laden with contaminant so as to precipitate and/or agglomerate the contaminant, then separating said contaminant so as to obtain treated water.