I've heard the same. Also I am sure there are people who drink nothing except coffee; they never have pure water or similar, but they don't die of dehydration. The body gets good at extracting water from this stuff. You can extract some water from food, too.
Which isn't to say that if water is short you shouldn't drink it neat instead of making coffee with it, but if it is already in the form of coffee then it will do you good. Unlike, say, beer, which you are better off not drinking. Or sea-water or neat urine.
That said, I like my coffee white, and powered milk and creamers are horrible, so I will probably give up coffee if the balloon goes up.
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Quality is addictive.