How many nanometers does this filter down to? I have a LifeSaver 4000 water filter that filters down to 15 nanometers, but is not designed for backpacking and weighs about 30oz. It is a great filter and packs easily, but for weight purposes, it's a little heavy. However, I can't seem to find a filter that filters down to anything less than 0.2 micrometers or 200 nanometers.

I agree with phil maher completely. 0.2 Microns is more than sufficient to get out all of the 'bad stuff' in backcountry water...the stuff that will make you sick (particulates (dirt), protozoa (giardia and crypto), and bacteria (campylobacter is the smallest pathogenic bacteria in backcountry water at 0.2 microns). Viruses that are typically about 0.01 microns, or 10 nanometers in diameter, simply can't be taken out of the water effectively mechanically. Chemicals such as Chlorine Dioxide, Sodium Hypochlorite, and even Iodine (though iodine will make the water taste horrible) do so very easily within about 5 minutes per liter to EPA standard (99.9999%). The issues with a backcountry water filters not only deal with what they can take out efficiently, but how they perform over a certain period of time. As important as efficacy, one has to consider pump volume, size, weight, ease of use, can it be serviced and maintained in the field with little mechanical knowledge, etc. The Hyperflow does all of these well once the basic tenants of this filter are understood. The HyperFlow isn't great for heavily sedimented water or one with a large amount of humic acid or blue-green algae (substances that are notorious for clogging filters...the MiniWorks EX is a better choice). I consider the HyperFlow to be the best high mountain filter available. It is smart to do some research on the types of water you'll encounter in the area you'll be hiking/backpacking however. This should play a part in what filter you buy.

The filter pore size is 0.2 microns.