These people won't use this water for washing; they'll only use it for drinking. Although they received so much water at once, I don't think they will reserve it all for drinking. Each person will probably take an appropriate amount.
There's another point worth mentioning: the water Lin Yi provided is untreated river water, completely unpurified. Isn't it going to cause stomach troubles for those who drink it?
Why doesn't Lin Yi give them some purified water?
Haha, just kidding. To these people, this kind of water is even purer than purified water.
For people who already have the periodic table accumulated in their bodies, this water is as clean as can be.
It's just like when you offer purified water to Ah San in future generations; they might get stomach troubles instead since they're already accustomed to the Ganges water.
After all, in their eyes, the water from the Ganges is clean and hygienic.
