Those links on Sodis were quite interesting to follow. Seems so simple, just need to get the word out. Does anyone know if Sodis has been studied for elimination of Giardia and Cryptosporidium or other nasties common in the U.S. backcountry? If so, a redesign of hydration bladders so that they're more transparent might make the technique a worthwhile addition to a hiker's skillset. It looks like Sodis is more targeted to 3rd world countries and large scale disaster situations which might be dealing with different pathogens.