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For so many, that morning cup of coffee is essential, but as long as they've consumed it, coffee drinkers have been told that shot (or shots) of caffeine can leave them dehydrated.

"I would say that if I'm drinking coffee, that I would generally like to follow the coffee with a water," said Darcy Cadman, a patron in a New York coffee shop.

While it's true that caffeine can be dehydrating, a study today in PLOS ONE found that wasn't the case when it came to drinking moderate amounts of joe.

Related: Five common caffeine myths busted.

Researchers at Birmingham University took a group of 50 healthy men and had half of them drink four small mugs of coffee daily for three consecutive days. The other half drank four small glasses of water. Then the men switched.

The study results: There was no significant difference in the men's hydration levels.

Coffee, after all, is made up of more than 95 percent water.

"This is great news," Taylor Sele said. "This is absolutely great news."

ABC News' Jared Wiener contributed to this story.