Take the questions out of questionable water with these KatadynA(R) MicropurA(R) MP1 Water Purifier Tablets. Work great with hydration packs and a 4-hr. treatment time is required for effectiveness. 30 tablets 4 ppm of chlorine dioxide Proven against viruses, bacteria and cysts, protozoa and similar microorganisms Improves odor and taste of water 1 tablet treats 1 liter of water 4-hour treatment time