For a really novel (urban survival in So Cal???) approach, see this link. (I recall that c. parvum is supposedly hard to kill with short exposure time to UV due to shell thickness).<br><br>I found mixed claims about chlorine dioxide (AquaMira) VS c. parvum, so caveat emptor as always.<br><br>Having a devil of a time getting useful info about Chlor-Floc - I guess the issue "emergency kit" includes a reusable mixing bag/bladder and a reusable filter. If, as the name implies, the chemical disinfectant is chlorine, surely it is pH / temperature dependant??? Wierder yet, the current military pubs I've looked at that mention Chlor-Floc are still listing iodine as the prefered chemical treatment (at the individual level)... Chemical name for it is sodium dichloro-isocyanurate - sounds like a powdered superglue with chlorine <grin>.<br><br>BTW, boiling does not render water safe for storage, but only for relatively immediate use - many bacterial spores survive boiling (not a problem to drink them, but if the water sits for days, I guess they can eventually re-infect the water...?)<br><br>Oh - another bit of trivia I found is that many individuals seem to become "immune" to c. parvum, but the mechanism is not established yet. Also, many folks are asymptomatic, just like with giardia. Not everyone gets sick... in fact, some studies suggest that most of us won't get sick, or only slightly. No comfort to those who have died from it, of course.<br><br>When I was in a 3rd world country during a bit of civil disorder, the MSF folks and others told me that more people were dying from the effects of diharea (mainly dehydration) than starvation - bad water and/or hygene. I've often recalled that and near as I can tell, there's quite a body of evidence that supports that claim.<br><br>Now, if I could only fit a PUR in my PSK... nah. I'll stick to iodine for now. I must admit tho, that the c. parvum info is making me at least consider a filter for planned trips. Look forward to reading whatever additional info folks dig up on the topic.