Cup of water (English Sub)

Talking about the water cycle, Gordon Wilson writes -
-----------------------
Since water inevitably flows from "us" to "them" we must take care that our outgoing water is as good as our incoming water, or at least not harmful for man, animals, and plants by the time it is used. Since we are very accomplished at fouling water in countless ways, it is of paramount importance for us to love our neighbors by taking full responsibility for it being clean before it gets to others. Water is an immense gift from God, but we all share it, use it, and reuse it on a local to global scale. Our dominion responsibilities include water care because all life depends on it. The Scriptures say, "And whoever gives one of these little ones even a cup of cold water because he is a disciple, truly, I say to you, he will by no means lose his reward" (Matt. 10:42). Think about it: if by that man's irresponsible actions that cup of water is not fit to drink, I dare say he will lose his reward. I don't think I'm on skinny branches theologically to judge how drinkable these cups of water are, especially at a societal level.
-----------------------------
from the book "A Different Shade of Green" by Gordon Wilson - pages 69-70