Potable Aqua Chlorine Dioxide Water Purification Tablets are for the emergency disinfection of drinking water. When used as directed the tablets make contaminated water suitable for drinking. Potable Aqua Chlorine Dioxide Water Purification Tablets are for use by campers hikers militaries emergency organizations and anyone needing to drink water of questionable microbiological quality. Effective against viruses bacteria and cysts - such as Giardia and Cryptosporidium.