Your Trusted SourceMSR engineers designed the new Guardian purifier to be the safest and easiest way to purify water virtually anywhere on earth. Achieving such a high degree of performance required advancements in technologies, and a great deal of engineering ingenuity. After six years of R&D, with expertise provided by our water research lab, the result became the world’s most advanced backcountry water treatment device. The Guardian purifier is able to transform even very challenging water so