Lessons learned in water filter shopping

Liz and I just spent our evening researching water filters for emergency preparedness, and hopefully we can save other people some time by sharing what we learned.

First: a filter needs to be 0.2 microns or smaller in order to reliably get rid of giardia and cryptosporidium spores. Most of the filters we found only made it down to about 3 microns (over ten times too big), and would only filter 20 to 50 gallons before you have to replace the filter.

However, Sawyer has a line of systems with a 0.1-micron filter and a "million gallon guarantee." After mulling over the various options, we finally narrowed down our search to these two products:

1. Four-way 32-ounce system: Comes with a 32-ounce water bottle and adapters for camelbak-style bladder bags and standard kitchen faucets.
2. Squeeze system: Comes with 3 squeeze bags (1/2 liter, 1 liter, and 2 liter), which can easily be rolled up for compact storage. The filter's can also attach directly to a standard 2-liter bottle.

Both have excellent (though sparse) reviews on Amazon. We ended up going with the first option because of the various adapters that it comes with. For serious hikers, the second one is probably the way to go.