Potable Aqua® Chlorine Dioxide Water Purification Tablets are for the emergency disinfection of drinking water. When used as directed, the tablets make contaminated water suitable to drink. Potable Aqua® Chlorine Dioxide Water Purification Tablets are for use by campers, hikers, militaries, emergency organizations, and anyone needing to drink water of questionable microbiological quality. Effective against viruses, bacteria, and cysts – such as Giardia and Cryptosporidium. Requires a 4-hour treatment time for effectiveness. Effective against bacteria, viruses and cysts, such as cryptosporidium. No aftertaste – improves the taste and odor of water. Proven effective against Giardia Lamblia, Cryptosporidium, and viruses. Great for camping, hiking, international travel and emergency situations. Ideal for use with hydration packs.