Wow, that's a new one on me; thanks for the update. I didn't realize anyone was doing mechanical filtering of viruses.

I did some googling and it seems like the Sawyer company is a little hit-n-miss with data and customer service, but it still bears investigating. Though, I can't imagine a 0.02 micron filter (yes, that's 2/100ths of a micron!) doing very well with anything but crystal clear intake water.