I usually take a couple of litres of water with me and once that has run out, depending on location, I use a milbank bag filter, a sawyer mini and then boil. Never had an issue so far, but where I live we have good fresh spring water from the hills. They even sell it
That's exactly my method too. It works fine. , even with fairly suspect water, but I always try to find fairly clean supplies.
I also have a water to go bottle which can filter pretty nasty looking water, havnt tried to do that with it myself, but I've seen a live demo where it came out clear and drinkable. No upset tummy either after drinking . No nasty tastes and what went in was pretty green and nasty!
I don't know why it's not more popular as a water treatment option.