Katadyn Micropur Water Purification Tablets (30-pack) kill Cryptosporidium, Giardia, bacteria, and viruses using the same proven technology as municipal water supplies. The Katadyn Micropur Tablets are compact, lightweight, and easy to use. The recommended contact time for killing all specified contaminants is 4 hours. The Katadyn Micropur Water Purification Tablets are for the emergency disinfection of drinking water. Active ingredient in this product is chlorine dioxide. These tablets are easy to use, lightweight, and convenient for emergency use while traveling, hiking, backpacking, or at your own home. The Katadyn Water Purification Tablets produce fresh tasting water without the unpleasant taste of iodine tablets.