Yeah, so far so good
! I've been relying on my MSR MiniWorks EX to filter out anything bad, with the exception of viruses of course. While the area does border some private property, it's pretty doggone empty out there, and we've been playing the odds that there's only a very, very small chance that something really nasty is in the water. There's always pills and boiling of course, but I have been thinking about upgrading to a 100% water purifier. Just haven't dropped the bucks. I have seen the water foam out there in the small streams, but most of that is probably just due to natural "pollutants" such as pollen, dust, etc.
Although I haven't tried it yet, my MSR MiniWorks EX (like most MSR EX pumps) incorporates a charcoal core to remove bad tastes like iodine, so you're supposed to be able to iodine-treat the water first for the really bad nasties and then pump it to remove the bacterias and bad iodine taste. I might have to try it at home to see how the water tastes.
If so, then that is pretty much as close to 100% as you can get.
rgds,
WestTexas