Fun fact: caffeine's actual toxicity is so low that if you were to off yourself by drinking coffee, water overdose would get you before caffeine overdose.
@AmpBenzScientist water's fine, I've heard of an experiment where an intern accidentally measured an order of magnitude more caffeine than intended into plain glasses of water and sent 2 people to the hospital for weeks. It's just that the concentration of caffeine in water to achieve its intended effect is much lower than what's needed to be toxic.