It will kill a high percentage of living organisms, so decrease the
load which MAY be enough to keep you healthy.
SODIS is often used in tandem
after other water purification methods such as flocculation, settling, cloth
filters, biosand filters etc. This can greatly reduce the load and should keep most if not all folks in good shape.
I have used SODIS in Tibet, had no problems, but do not know if
there were any pathogens in the water to begin with.
I consider it a backup or an adjunct.
For treating water in a hurry for personal drinking I like
http://www.cabelas.com/spodw-1/0024875.shtmlPour it in and start drinking. The only one I know of that
has filter, iodine, charcoal all in one.
It looks like a water bottle, so your hosts will think nothing of
it when you pour your water in. It does not supply a lot of water
however, but is handy while waiting for other disinfectant methods to work.