A boy is in a community where only certain people have some sort of telekinetic powers and his brother has them. The society leaders believe the brother is the 'chosen one' but it's actually the main character. A specific scene had him fighting his brother and was pushed into some water and he was drowning, but he 'discovered' his power by teaching his body to change the water molecules to oxygen. I have no clue what the book is called but it is driving me crazy that I don't know it.
Freakling by Lana Krumwiede
In twelve-year-old Taemon’s city, everyone has a power called psi—the ability to move and manipulate objects with their minds. When Taemon loses his psi in a traumatic accident, he must hide his lack of power by any means possible. But a humiliating incident at a sports tournament exposes his disability, and Taemon is exiled to the powerless colony.
The "dud farm" is not what Taemon expected, though: people are kind and open, and they actually seem to enjoy using their hands to work and play and even comfort their children. Taemon adjusts to his new life quickly, making friends and finding unconditional acceptance.
But gradually he discovers that for all its openness, there are mysteries at the colony, too—dangerous secrets that would give unchecked power to psi wielders if discovered.
When Taemon unwittingly leaks one of these secrets, will he have the courage to repair the damage—even if it means returning to the city and facing the very people who exiled him?