I backpack allot. I use a water purifier as often as possible. I do carry, as a backup, iodine tablets just in case something happens to my filtration unit. Mine is a PUR. I never never never drink out of a stream or spring. You never know what has died near the stream or if the BLM leaves cattle running on the land and they make a terrible mess near and around water. I watched 2 guys one year, who had taken a nice buck, dragged it down to the stream to clean it up and themselves. Since I was spotting an area I watched them and they followed the stream down and at one point I saw them drink out of the same stream. Sometime people are not all that bright or really have no knowledge or cares. If you contract the virus and don't take something for it, it could kill you if not treated in time. Think about it, your hunting 7-8 miles up in the high country, you don't use the filtration system or tablets and take a cool drink from a stream figuring the water is safe. Then when you least expect it, expeccialy when your hunting hard everyday and expending allot of energy, you start to feel weak and sick and decide that you may be tired and try and rid the feeling by sleep. At this time you should really be heading out to your vehicle. Always be safe, why trust the water when you can prevent from getting something from it.