Your response highlights my main concern - I noticed this problem in some of the commercial kits, including some of those reviewed on ETS. You and I have thought this problem through, but what about the people who just buy the kit and figure they're set? It may not kill them to overdose on iodine or chlorine, but ... if you're using the kit, you're usually not in a good situation to begin with. I hope the kit makers will think this issue through a little better before just tossing any old size of plastic bag in and figuring that they're done.