@ Paul D
“I would think that a .01 micron filter will get all bacteria and a lot of viruses.”
Since they are making no claim about filtration of harmful micro-organisms, the only logical conclusion I can make is 1) they are not testing the product against any standard and 2) they are not specifying their subcomponents to perform to any standard. Both factors enable them to cut cost and to reduce liability.
For bacteria, the EPA standard is to reduce up to four 9s, that is filter out 99.9999% of bacteria.
In reference to 0.1 microns, I think the MSR website sums it up:
“Micron ratings aren’t always the best way to gauge effectiveness. Test procedures for micron ratings vary so greatly that comparing them is misleading. In addition, micron ratings for filters do not tell you how the product will perform with actual bugs. There is an EPA Guide Standard for Testing Microbiological Purifiers, which describes how to test products to determine if they are removing or inactivating the proper number of pathogens in different types of water throughout the life of the device. When looking for a microfilter or purifier ask if the product has been tested according to the EPA Guide Standard and passed. For a microfilter, meeting the EPA Guide Standard means removing 99.9% of protozoa and removing 99.9999% of bacteria in all required water types. To be classified as a purifier, the device must meet the EPA Guide Standard for the removal of protozoa and bacteria as well as virus which must be inactivated to 99.99% in all required water types. All of the MSR filters and purifiers have passed the levels of inactivation required by the EPA Guide Standard with flying colors.”
Of course 90% of the time in the places where the typical BPLer backpacks, the water most likely does not need to be treated. Each person has their own risk profile. I almost always treat my water because I have seen the consequences of bad water.
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