Solar “ovens/stills” will pasteurize water. Heck, your car will work if you live in a sunny and warmer climate. Boiling for ten minutes or warming to 140 for ~6-8 hours will acomplish the same thing. I have a few solar shower bags stashed for hygene and pateurizing. Given rain, a fresh water stream and sunlight you can do a lot.
Solar is not that dependable in many areas of the country and boiling is an energy ‘hog’ and as you said you need to start with relatively ‘clean’ water to begin with.
It will kill the organisms, but it wont take out all the toxins likely to be present is surface water.
Solar pasteurizing of water is not the same as distilling. It may kill some bacteria but the solids are still in the water and if you have a dead emu upstream......