Is there such a thing as caffeinated water?

As a matter of fact, there is!  One company called "Water Joe" describes their water as "pristine artesian water, tapped from a protected aquifer deep beneath the land in northeastern Wisconsin. With a shot of natural caffeine extracted from coffee beans, which is tasteless and odorless. Think of it as a sugar-free, carb-free, calorie-free alternative to energy drinks. Water Joe comes in three sizes so you can pick the amount of caffeine you need to get your work done."