Effective water purification with no after taste the lifesystems chlorine dioxide tablets kill bacteria viruses and cysts in water making it safe to drink for 2 3 daysthe lifesystems chlorine dioxide tablets and effective and very easy to use simply add 1 tablet per litre to relatively clear and debris free water if the water is very cold or if giardia or cryptosporidium is suspected add 2 tablets per litre of water swirl gently and wait for at least 10 minutes before drinking or 30 min