Be sure to stock up on replacement cartridges for your SurvFilter! Whether you&';re using the filter for hiking, camping, or because of a natural disaster, you can be secure in the knowledge that the SurvFilter will provide clean drinking water to keep you alive. When water flows through the SurvFilter, there&';s an ionic exchange that captures the viruses and bacteria so you get clean drinking water. (Imagine the filter is a magnet that extracts all of the bad stuff.)