One more reason why I stick to plain old canteens instead of "hydration systems" - they are just too fiddly. Most of my canteens have fairly wide orifices, along with water tight caps just for that reason.

Most of my SAR experience has been in southern Arizona, centered around Tucson. As one of my colleagues put it, in the summer, your call out pack simply becomes "a giant water bottle" along with some first aid gear. If we needed water, we took whatever time it required. This was often collecting water from small seeps and drips, sometimes in circumstances where we did not need to be concerned with water purification measures. I sometimes carry a Katadyn Hiker filter if speed is of the essence. I note that most chemical treatments require about 30 minutes or so before becoming effective, a time that is about equal to the time required for boiling, assuming a decent stove.

Again I really like boiling if you must be serious about purifying water. You can boil water in widely varying circumstances, with many kinds of simple gear, and it is definitive and more fool proof that other techniques.

The worst water I ever dealt with was stream water from Canyon del Muerto, Canyon de Chelly National Monument, Arizona. High water levels after an extremely wet winter halted vehicle access for the first half of our field season, so we hiked to our dig from the top of the canyon. Canyon del Muerto holds a population of around two hundred or so inhabitants, plus several hundred sheep. The only toilet facilities I knew of in the canyon were at the ruin we were excavating, so we treated the water. The first step was to let it settle overnight to deal with suspended sediment. Then it was boiled. We used that water for about four weeks until we could resume driving in the canyon. No problems at all with Montezuma's Revenge.

As always, you need different options for varying circumstances, but it fairly critical that your treatment be effective for the water you are consuming.