This package of Aquatabs contains 50 tablets per package. Each tablet treats 1L. For dirty, cloudy, stained and/or cold (4° C) water, double dosage to two tablets. Aquatabs purifies water for camping, hiking, boating and international travel. Aquatabs are effective against Giardia cysts, bacteria and viruses, making water safe for drinking, brushing teeth, cooking and washing fruits, vegetables and produce. Aquatabs are Iodine-Free, Chlorite-Free and individually foil sealed with a 5-year shelf life from the date of manufacturer. When dissolved in water, Aquatabs produce a measured dose of free chlorine. Aquatabs are NSF 60 Approved. The active ingredient in Aquatabs, Sodium Dichloroisocyanurate (NaDCC), is registered by the US Environmental Protection Agency (EPA) for routine treatment of drinking water,; meets European Standards for drinking water (EN12931: 2000) and the World Health Organization (WHO)/The Food and Agricultural Organization (FAO) specs for drinking water.