Dehydration is one of the main concerns related to caffeine over consumption. Caffeine affects the kidneys by acting as a diuretic, which increases urine production and therefore increases loss of water from the body. Numerous studies have provided evidence linking this loss of fluid with high levels of caffeine consumption, often 600 milligrams or more per day. There is little indication of a diuretic effect for individuals who consume moderate amounts of caffeine, less than 300 milligrams, or 2-3 cups, of coffee per day. Also, there is some evidence that people who regularly consume larger amounts of caffeine have a higher tolerance to the diuretic effect.

Ok, so here is my final answer...apparently, it depends on how much you drink...back in the Pepsi days, you were probably drinking so much that you were unaffected by the diuretic effects of caffeine.:)