I've been using an Aquamira filter bottle for about 10 years and have never felt the wrath of Montezuma:
http://www.trailspace.com/gear/aquam...le-and-filter/

I've changed the filter 4 times, which is probably overkill (it's rated for 50 gallons before replacement). Only negative was that the plastic guard cap came off within the 1st year; doesn't effect performance.

Regards,
Scott