Alessandro,
Yes, I agree that doing something is sometimes better than doing nothing at all.
There were 9 posts in the thread. I hope you were able to review them. Not all of them are noteworthy, but there are good references in some of them. The one that struck me the most was the one that said, if it is a choice between plentiful dirty water and limited treated water, plentiful water is more important to good health than clean water, statistically.
From what I have read, SODIS is a viable option in many circumstances, but you must start with clear water, you must have bottles made of the right material, the bottles must be properly sterilized between uses, among other things, so, like many other methods, it is not idiot proof.
If I had to prioritize: 1) access to fresh water (even if it is thick as mud), 2) treat for turbidity, 3) treat for remaining pathogens, 4) treat for remaining toxins
That does not address distribution and storage.
In researching the subject for a reply to the thread, one writer mentioned that protecting water quality can be more effective than water treatment. I remember watching a documentary on eliminating schistosomiasis in a Caribbean island by creating water storage upstream of areas contaminated with schistosomiasis carrying snails and piping the water to the villages for bathing, washing, drinking and cooking. I never saw or read a follow-up of that project to learn if it had long-term viability.
You may also be interested in reviewing plans and theory behind a novel Solar Distiller design here:
http://www.bioenergylists.org/aprowinstill