Wherever life takes you, never be without clean drinking water when you have Potable Aqua Chlorine Dioxide Water Purification Tablets. These tablets are effective against viruses, bacteria and cysts such as Giardia lamblia and Cryptosporidium, and the water purification tablets for drinking water leave no aftertaste. Add these water treatment tablets to one quart (or one liter) of contaminated water, and allow four hours of treatment time for emergency water purification. The combination of active ingredients in these portable water treatment tablets react to create chlorine dioxide, a powerful disinfectant that meets EPA microbilogical purifier standards to make questionable water safe to drink in emergency water purification situations.