I can only give you insight on the AZ water that I treat, which varies from (relatively) clear pools trapped in the bedrock found in the Superstition mountains to clean flowing streams in the transition zones.
On a recent 45 mile trans-wilderness hike we used water found at the spring troughs and with my bandanna as a prefilter I can squeeze and release an aquamira bottle to fill it that way. Then add the pre mixed aquafina that has been :brewing: while I fill my 2 bottles. Other times, the force of the water from a pipe or in a stream will fill the bottle/prefilter by itself. This is a simple way to rid the floaties from my palate :0)
I used a PUR filter for a few years, and never gave much thought to using aquamira drops, and now I kick myself for not trying this method earlier!
I would only use a filter for the most stagnant of pools, but fortunately most of us have experience to find good water, even in AZ with it's 11 year drought. A friend of mine also used that little filter from the BPL store, but modified it with a hose to make a gravity filter. Pretty cool!