Originally published on February 12, 2015. Viruses take the cake as tiniest of the waterborne disease-causing microorganisms—smaller than both protozoa and bacteria. These nasty little bugs are also the least understood by scientists, and cause the greatest range of symptoms across infected individuals. The good new is, in North American backcountries, viruses are typically considered much less of a concern than the other pathogenic threats.
Purifying your water of viruses has traditionally been a hassle. These devices are changing that.