Better tasting than chlorine and potentially less harmful than iodine, these Micropur Purification Tablets rely on Sodium Chlorite (i.e. Chlorine Dioxide) to penetrate and kill cysts, viruses, bacteria, protozoa, worm eggs and giardia. Simply wait 30 minutes with normal H2O under typical conditions or 4 hours for Crypto in freezing cold muddy H2O before drinking from your newly purified H2O supply. These precisely measured tablets are ideal for purifying small quantities of H2O anytime, anywhere - especially while traveling, in hotels, and ultralight trips. If you necessity H2O quickly or rely on sources with gritty or muddy runoff, consider using the Katadyn Guide or Hiker Microfilters.