Caffeinated Water 101

How does caffeinated water compare to energy drinks in terms of ingredients and safety? What does the latest research say about caffeine and hydration? As a food scientist who’s studied the science behind energy drinks since 2003, I believe caffeinated waters can be a great alternative to the stereotypical energy drink, but there’s a lot more to consider before deciding whether caffeinated waters are right for you.


  • Caffeinated Waters 101 – Safety, Science, and Preferences
  • Caffeine and Hydration – What does research tell us?
  • Caffeinated Water Spotlights


Caffeinated Water 101


In this presentation:

What is caffeinated water? How is it different from an energy drink? Are caffeinated waters safe? How do you know if caffeinated water is right for you, or which one to try?

Caffeinated waters, like enegy drinks, are a spectrum. Some caffeinated waters are literally just caffeine and water, but other caffeinated waters also have flavors, colors, sweeteners, and/or preservatives.

Let me tell you where the caffeinated water spectrum stops. The FDA has issued warning letters to companies for using the term “water” on a water beverage with added sugars because the definition of water implies it is Calorie-free. Therefore, in our discussion of caffeinated waters, let’s exclude the “water beverages” that are not Calorie-free.

In general, caffeinated waters will have less complicated formulas than the stereotypical energy drink. For example, you’re much less likely to find the taurine, carnitine, glucuronolactone, and guarana. The good news is, you don’t have to worry about whether or not energy drink ingredient interactions make energy drinks more dangerous than coffee.

But that doesn’t mean that all caffeinated waters will be artificial free.

One should also avoid the assumption caffeinated waters are safer than energy drinks, caffeine-content wise. Some caffeinated waters have more caffeine than some energy drinks, per container. Just like with energy drinks, you really have to take responsibility for your safety by checking the caffeine content is not more than you can handle. For reference, Adults can have up to 400 mg caffeine per day and up to 200 mg caffeine per sitting/occasion.

So how do you know if caffeinated waters are right for you?

  1. Make sure the caffeine content is what you need.
  2. Make sure the ingredients don’t include anything you’re trying to cut out of your diet.
  3. Make sure you’re actually looking for caffeine and not just some way to get yourself to drink more water. There are plenty of other ways you can do that without caffeine.

What does SCIENCE tell us about caffeine and hydration?

In this presentation:

Does caffeine really make you pee? Is caffeinated water a paradox (hydrating and dehydrating you at the same time)? Is there a difference between water, caffeinated water, and energy drinks when it comes to hydration?

Note – this presenation contains some general scientific summaries but it also contains some pretty nerdy technical details about the kidney, glomular filtration, and how females have different activity than males for cytochrome P450.

IF YOU ARE NOT INTO THE SUPER-NERDY SCIENCE, I’ve embedded some videos of my bulldog puppy playing at the beach and the park during all the super-sciency parts of my presentation. 

Here are some basic summaries from the research on caffeine and hydration:

  • Caffeine intakes greater than 250 mg do seem to increase urine output but only for people who don’t normally consume caffeine or after about a week of caffeine-abstinance
  • Environmental temperature and physical activity both counter-act caffeine’s diuretic effects (*diuretic meaning increasing urine output)
  • Women are more susceptible to caffeine’s diuretic effect

While I was reviewing the research, I was most surprised that it matters whether it’s just caffeine and water or caffeine, water, AND other ingredients. When it’s in the form of plain black coffee or tea, there WAS NO difference between water and caffeine. However, a combination of caffeine, water, AND carbohydrates DOES NOT hydrate as well as the caffeine-free combo.


Caffeinated Water Spotlights

Hydrive Energy Water

If you’ve tried other energy waters and wanted more flavor, more sweetness, maybe a little more color, then try Hydrive. It’s more than just caffeine+water but still a healthier alternative than the stereotypical energy drink.
IN THIS REVIEW from the GreenEyedGuide archives:
✔What the key ingredients do,

✔How the caffeine compares to other energy waters and energy drinks

Avitae Caffeine + Water

Wrapping up our focus on Caffeinated Waters this week, I wanted to highlight a caffeinated water fueled by green coffee beans.

I had the honor of talking to Avitae president and CEO about how Avitae picked their flavors, how difficult it was to hide caffeine’s bitterness in something as neutral as water, what keeps him up at night, what he’s most proud of. I hope you enjoy these Q&As whether you’re a food scientist, future product developer, or just a caffeine lover.

Guru Energy Drink

Guru Energy Waters offer a simple ingredient list: carbonated (or “sparkling”) water, erythritol, flavor, green tea extract (the source of caffeine), juice concentrate, and Stevia.

It comes in a can like an energy drink but Guru’s Energy Water tastes WAY more like water than another energy drink. If you’re looking for something with Organic ingredients, ~100mg caffeine, light flavor, no Calories, no sugar, no artificial colors or flavors or sweeteners, this is worth a try.

You can read the full analysis of Guru Energy Water here on GreenEyedGuide

View this post on Instagram

Alas, this is the end of our Caffeinated Water Week. Our final caffeinated water spotlight goes to @guruenergydrink which is fueled by green tea extract. ✔It comes in a can like an energy drink but Guru's Energy Water tastes WAY more like water than another energy drink. If you’re looking for something with Organic ingredients, ~100mg caffeine, light flavor, no Calories, no sugar, no artificial colors or flavors or sweeteners, this is worth a try. ✔What’s In It: Key Ingredients and Functions- Guru Energy Waters offer a simple ingredient list: carbonated (or “sparkling”) water, erythritol, flavor, green tea extract (the source of caffeine), juice concentrate, and Stevia. 👩🏼‍🔬💚☕ Full Review at

A post shared by Danielle Robertson Rath (@greeneyedguide) on

Finally, don’t forget to check out the Energy Drink of the Month for April 2018: Hint Kick caffeinated water

Hint Kick has only three ingredients: purified water, natural flavor, and natural caffeine from coffee bean extract (aka green coffee beans).

Hint Kick isn’t the only caffeinated water to use green coffee beans but in this Energy Drink of the Month review, we recap the latest green coffee bean research.

Energy Drink of the Month HINT KICK



Zhang Y, Coca A, Casa DJ, Antonio J, Green JM, Bishop PA. Caffeine and diuresis during rest and exercise: A meta-analysis. J Sci Med Sport. 2015 Sep;18(5):569-74. doi: 10.1016/j.jsams.2014.07.017. Epub 2014 Aug 9. Review. PubMed PMID: 25154702; PubMed Central PMCID: PMC4725310.

  1. Kingsley M, Penas-Ruiz C, Terry C, Russell M. Effects of carbohydrate-hydration strategies on glucose metabolism, sprint performance and hydration during a soccer match simulation in recreational players. J Sci Med Sport. 2014 Mar;17(2):239-43. doi: 10.1016/j.jsams.2013.04.010. Epub 2013 May 20. PubMed PMID: 23702257.
  2. Killer SC, Blannin AK, Jeukendrup AE. No evidence of dehydration with moderate daily coffee intake: a counterbalanced cross-over study in a free-living population. PLoS One. 2014 Jan 9;9(1):e84154. doi: 10.1371/journal.pone.0084154. eCollection 2014. PubMed PMID: 24416202; PubMed Central PMCID: PMC3886980.
  3. Hildebrandt GH, Tantbirojn D, Augustson DG, Guo H. Effect of Caffeinated Soft Drinks on Salivary Flow. J Caffeine Res. 2013 Sep;3(3):138-142. PubMed PMID: 24761280; PubMed Central PMCID: PMC3777298.
  4. Ruxton CH, Hart VA. Black tea is not significantly different from water in the maintenance of normal hydration in human subjects: results from a randomised controlled trial. Br J Nutr. 2011 Aug;106(4):588-95. doi: 10.1017/S0007114511000456. Epub 2011 Mar 30. PubMed PMID: 21450118.
  5. Maughan RJ, Griffin J. Caffeine ingestion and fluid balance: a review. J Hum Nutr Diet. 2003 Dec;16(6):411-20. Review. PubMed PMID: 19774754.


I’ve researched the science and safety behind energy drinks and their ingredients since 2003. This book is the culmination of my research:

Need help with quitting caffeine?

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