Overland Journal did a test of purifiers that included a laboratory component to see if the purifiers actually, well... purified.
The Steripen was the only one that didn't render water safe to drink. OJ went back and forth with Steripen's manufacturer to see if they were missing something. One of SP's claims was that the organisms weren't removed but were rendered inert. Fair enough. However, SP "purified" water that was left to culture for a few days showed a marked increase in the number of microorganisms. Nothing inert about them.
So, aside from the battery issues (I've seen that failure in the field too), Steripens don't actually purify. Pretty much a No-go.
http://www.overlandjournal.com/medi...ompletes_water_filter_and_purifier_test/
