Can drinking caffeine, alcohol and other diuretics be part of a good drinking regime?
A PlOS One study notes drinking moderate amounts of coffee (aka moderate caffeine intake) doesn't necessarily lead to dehydration. They note coffee has hydrating qualities akin to water. Further empirical studies found no substantial fluid loss in caffeinated beverages.

EDIT: Make note we're talking normal doses and moderate intake, though source 2 goes into diminishing effect of caffeine-mediated fluid loss in heavy/prolonged uptake.

The issue therein is with alcohol, which tends to inhibit vasopressin and the kidneys are constantly permeable to fluids.