The present invention is directed to a water treatment composition, containing 50-99.9 wt. % of particulate halogen-releasing compound； and 0.1-10 wt. % of granular fluoropolymer, wherein all weight percentages are based on the total weight of the composition. The present invention is also directed to a water treatment composition, containing 50-99 wt. % of particulate halogen-releasing compound； 1-10 wt. % of aluminum sulfate； 0.5-15 wt. % of a sulfate salt selected from the group consisting of copper sulfate, zinc sulfate, and combinations thereof； and 0.1-10 wt. % of particulate polytetrafluoroethylene polymer, wherein all weight percentages are based on the total weight of the composition. One particular halogen-releasing compound is trichloroisocyanuric acid.
