On a trip in Western China the locals cooked every food and drank tea made with water just brought to a boil. Much of the water came from cisterns that had livestock wandering about over the ground surface so sheep, pig and yak dung was everywhere. They reported that no one got sick from it. I didn't either. In fact I had trouble in the city from bottled water before I got to the highlands.

If the water is clear, I just bring it to a boil. Otherwise I filter or floc, then boil or treat with chemicals.

Washing hands is more important in my estimation.