In 1993, I was fortunate enough to be invited on a cave exploration and mapping expedition in Guizhou province, China. Our food and beverages were prepared by local cooks. I have no idea what the water sources were - perhaps the rice paddies?

Twelve of us were there for thirty days. A certified EMT at the time, I was prepared to handle lots of diarrhea cases. We had no occurrences. AFAIK, our water was treated only by boiling.

Boiling might or might not be all that convenient, but it is effective.