Compositions, methods and kits for purifying and clarifying and/or nutrifying contaminated drinking water and which comprise a primary coagulant material, a microbiocidal disinfectant and an oxidant system. Highly preferred compositions also contain one or more of a bridging flocculent material, the levels and ratios of coagulant to flocculent preferably falling within certain ranges, a cationic coagulant aid, especially chitosan, a water-soluble alkali, a water-insoluble silicate, and a food additive or nutrient source. The purified water remains free of discoloration for extended periods of storage.