Micropur MP1 water purification tablets are only for emergency disinfection of drinking water. When used as directed, the tablets make contaminated water suitable for drinking. When added to water, Micropur MP1 tablets release chlorine dioxide which is effective against bacteria, viruses and cysts, such as Cryptosporidium and Giardia. No aftertaste - improves the taste and odor of treated water. How to use: Remove the tablet from its foil packaging with knife or scissors and quickly insert into 1 quart (1 liter) of contaminated water. Allow to react for 4 hours in an opaque container or in the dark to generate a use solution of 4 ppm chloride dioxide. The treated water is now ready for drinking. Meets EPA Microbiological water purifier test standards. Warning: Keep out of reach for children.