The ability to manipulate, control, or create water by the force of will alone.
A common psionic power in many sf genres.

Typical Applications (usually, these require proximity to a large ready source of water):

"Water Spout" or "Create Wave" - The ability to cohese water into a large wave or spout.
"Whirlpool" - The ability to coerce water into a swirling vortex of water.
"Sense Water" - The affinity for H2O usually allows the bearer of the power to locate water within a short distance from the user.