I work for a large water utility. I own a Katadyn Vario also, Sawyer 3 way inline, Polar Pure, Micropur tablets, bleach, etc. I think SkunkHunter laid it all out perfectly. I'm really liking the reverse cleaning of the Sawyer products as well as the fact they are one of the few that sell filters for viruses. First Need also makes an excellent filter. This new Sawyer looks perfect for people who need to get clean water immediately:
The Squeeze filter will also fit on most small mouth water bottles.
http://www.youtube.com/watch?v=lKWQjlq-uYAHere is the "Purifier", most filters are good for .1 micron or larger but this one does .02 microns which explains how it can remove viruses and yet it has a 1 million gallon guarantee: