First of all, you should look at how dirty the river is. If it's like a gutter, don't eat it. If it's normal Yellow River water, it doesn't matter, as long as it's cooked enough. Prevent parasites. As the saying goes, big bacteria eat small bacteria. It's easy to get sick if you can't eat anything dirty. India is an example. The Ganges River water is heavily polluted, but there is nothing serious about people eating and drinking Lazar there. Is that the body adapts to bacteria.