Granted. You now operate a dam.

Granted, you must consciously control all the water inside your body at all times. If you break concentration for even a moment, you might accidentally rupture all your cells.

Everything you use your power, your hair falls out. It can grow back, but it takes a while.

Any water you control smells increasingly like piss the more you interact with it. As a byproduct, you generally start to be kind of a smelly guy

Granted. The water gets the power to control you back.