ShwoooOOP! Bank drive-throughs used to make me giddy with excitement. I would gaze through the window and perk my ears to hear the satisfying sound of a pneumatic tube suction away the deposited cash. A differential of air pressure allows for this cool system to take place. Your brain works similarly, albeit swapping air with another fluid: water.
Why is it important to drink water? There are many answers to this question, but the one you are likely interested in if you clicked this article is this: water is the vehicle of life.
Want to get a parasite? Drink from a static pond nearby the equator. Even smaller than parasites, bacteria are slothful on a dry surface. But give it water, and a bacterium (water speed: 10-100 microns/second) may travel over half a cm in a minute. Look at your pinky. Said bacterium could cross from the tip of your nail to the bottom of the finger in less than 2 minutes underwater.
But what if, then, the water itself has a current? The bacterium could then travel at hyperdrive, similar to how many science fiction novels have the fabric of space-time act as a warp speed for vehicular space craft.
There is no need to travel the galaxy to see this phenomena. It is inside you. This is the very notion behind the major fluids in the body: blood, cerebral spinal fluid, lymph, and mucus.
Your bodily cells are not bacteria, but are part of a hydraulic circuit more efficient than a bullet train. Muscles, chiefly the heart, exert acceleration on these tubular fluids and create gradients of pressure to nourish every cell of your body: the infrastructural "utilities" that keep you alive.
Thus, drink water.