Katadyn Micropur Tablets are the only EPA-registered purification tablets on the market and are effective against cryptosporidium, giardia, bacteria and viruses.Features: Leaves water with a clear, fresh taste - no chlorine odor or residue. Requires a 15 minute wait time for bacteria and viruses, and a 30 minute to 4-hour wait time for cysts like Giardia and Cryptosporidia (depends on water quality). Each tablet is individually sealed for maximum effectiveness. Specifications: Contents: Chlorine Dioxide. Output: 1 tablet treats 1 quart (1 liter) of water. Capacity: 30 tablets.