I thought I already posted this, But I don't see it? Oh well... Treating water with Chlorine doesn't kill all the bad stuff (e.g. Giardia or Cryptosporidium cysts), especially at cooler temps. Iodine kills only some of them. By definition A filter can not filter out viruses. So my question is: What temp will kill everything alive in the water. And, do I have do more than just bring it to a boil? What If I'm at 5000 feet where the boiling temp of water is 203F? Typically when cooking I use untreated water that I barely bring to a boil before dumping in dinner. I haven't ever been sick from it that I know of.