The LifeStraw, developed by Vestergaard Frandsen of Switzerland, has been reported by the American Journal of Tropical Medicine and Hygiene to be extremely effective for personal water purification in third world countries.
It comes in two styles, personal and family. The personal unit operates like a straw, while the family unit is gravity fed.
Internally the units consist of two fabric prefilters, an iodine chamber, and finally a carbon filter. It is capable of removing 99.999% of protozoa, bacteria and viruses, down to 15 microns in size. It is effective against the most serious waterborne illnesses, such as typhoid and diarrhea, that kill at least 2 million people every year in the developing world. For victims of hurricanes or other natural disasters it can provide a safety net until clean water becomes available.
The personal unit will clean about 185 gallons, and the family unit about 4700 gallons before needing replacement.
It has been suggested as an alternative for backpackers, but reports disagree as to whether this is a safe use. Giardia cysts (beaver feaver) and Cryptosporidium are smaller than 15 microns in size. These organisms are found in most North American natural waters and are sources of risk for backpackers.
However, the recent test reports from Vestergaard Frandsen show it exceeding US EPA standards of removal even for the 4-6 micron Cryptosporidium cysts.
The product is not yet available on the retail market.
See June 2009Vestergaard Frandsen press release
See Vestergaard Frandsen test results
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