"It's kind of hard to explain," Katara says, blushing a little at Tommy's enthusiastic compliments. "But I've seen polluted water before. My friends and I have been traveling through the Fire Nation, and we came across this village that was built in the middle of a lake. They were suffering because the water was all gunked up by a Fire Army weapons factory up the river from them, so we... uh, well, we helped clean the place up after the factory closed.

"The element you bend is a part of you. If it's tainted somehow, it just feels... wrong." The waves get larger, until one breaks away from the lake's surface in a gravity-defying swirl. "This just feels like water."