The chlorine dioxide tablets from lifesystems are a safe and effective method of disinfecting water and does not leave much of an after taste lifesystems chlorine dioxide tablets kill bacteria viruses and cysts in water including giardia and cryptosporidium and this pack will treat up to 30 litres of water once water has been purified it should be safe to drink for 2 3 days as long as it is kept in a sealed container that does not allow any light in e g a metal water bottle the chlorine dioxide