Do Green Tea and Coffee Count as Water Intake? Unpacking the Hydration Myth

October 24, 2025 •

3 min read

Studies, including one published in PLOS ONE, have shown that moderate consumption of green tea and coffee provides similar hydrating qualities to water, challenging the long-held myth that they are entirely dehydrating. This answers the question: do green tea and coffee count as water intake? Yes, but with some important caveats.

Quick Summary

Moderate intake of green tea and coffee contributes positively to daily fluid needs, as their high water content counteracts the mild diuretic effect of caffeine. Pure water, however, remains the best choice for optimal hydration.

Key Points

Count as intake: Yes, moderate amounts of green tea and coffee contribute to your daily fluid needs because they are mostly water.
Caffeine is a mild diuretic: The caffeine in these beverages has a diuretic effect, but for most people, the hydrating fluid content outweighs this mild effect.
Moderation is essential: Heavy consumption (more than 4-5 cups) can lead to a more noticeable diuretic effect and other negative symptoms.
Water is superior: Plain water is still the best option for pure hydration, as it has no diuretic effects or added calories.
Listen to your body: Individual caffeine tolerance varies, so pay attention to how your body responds and adjust your fluid intake accordingly.

Debunking the Dehydration Myth

For decades, a common health myth has persisted: that any beverage containing caffeine actively works against your body's hydration, effectively canceling out its fluid content. This misconception, particularly leveled against coffee and green tea, has caused many to avoid these popular drinks when attempting to stay hydrated. Recent and more comprehensive scientific evidence has largely debunked this notion, clarifying that the water in these beverages contributes significantly to your daily fluid intake. The key lies in understanding the mild diuretic effect of caffeine and its proportional impact relative to the total liquid consumed.

The Science Behind Caffeine and Hydration

At the heart of the myth is caffeine's property as a diuretic—a substance that increases urine production. Caffeine achieves this by boosting blood flow to the kidneys, prompting them to flush out more water. While this is true, the effect is often overstated, especially for regular caffeine consumers who build a tolerance over time. The amount of fluid lost due to the diuretic effect is minimal compared to the volume of liquid ingested, especially in moderate doses. For instance, a 2014 study found no significant difference in hydration status between participants who drank moderate amounts of coffee and those who drank the same volume of water.

The Role of Moderation

While green tea and coffee do count toward your fluid intake, they are most effective as a hydrating beverage when consumed in moderation. For most healthy adults, this means around 3 to 4 cups per day. Higher doses of caffeine, typically more than 500mg (the equivalent of more than 5 cups of strong coffee), can induce a more pronounced diuretic effect, though even then, it doesn't necessarily lead to net dehydration. Excessive intake, however, can cause other side effects like anxiety, jitters, and sleep disturbances, which is why moderation is so crucial.

Comparing Water, Green Tea, and Coffee for Hydration

To put their hydrating properties into perspective, consider how each beverage functions within the body. While all are primarily water, their overall impact differs based on their additional components and potential diuretic effects.


Feature	Plain Water	Green Tea (Moderate)	Coffee (Moderate)
Primary Function	Pure hydration, zero calories	Hydration + Antioxidants + Mild Stimulation	Hydration + Stronger Stimulation + Antioxidants
Diuretic Effect	None	Minimal to none	Mild, especially in regular drinkers
Fluid Contribution	100%	>95%	>95%
Other Effects	Regulates body temp, joint lubricant	Rich in polyphenols, may aid heart health	Boosts alertness, potential liver/diabetes benefits
Best For	All-day, consistent fluid replenishment	Health benefits, low-to-moderate caffeine boost	Morning wake-up, high energy boost

Other Fluids That Count Towards Hydration

It's important to remember that hydration isn't limited to just water, green tea, and coffee. Many other beverages and even foods contribute to your daily fluid needs. Including a variety of these can make meeting your hydration goals more manageable and enjoyable.

A List of Other Hydrating Fluids

Milk (including lower-fat options and fortified plant-based milk)
Fruit and vegetable juices (limited to 150ml per day due to sugar content)
Herbal teas (caffeine-free options are fully hydrating)
Soups and broths
Coconut water (unsweetened)
Water-rich fruits and vegetables like watermelon, cucumber, and oranges

The Importance of Listening to Your Body

The hydration needs of each individual can vary based on factors like activity level, climate, and overall health. Monitoring your urine color is a simple and reliable way to gauge your hydration status; ideally, it should be a pale yellow color. Thirst is another indicator, though by the time you feel it, you are already slightly dehydrated. For those who are sensitive to caffeine, its diuretic effect may be more noticeable, and they may need to pair their green tea or coffee with an equal amount of water to compensate for any perceived fluid loss.

Conclusion

The consensus among health experts is clear: do green tea and coffee count as water intake and contribute to your daily fluid requirements. While they are not a perfect substitute for plain water, which remains the gold standard for pure hydration, moderate consumption of these beverages is not dehydrating and can help you meet your fluid goals. The key is balance and moderation. For optimal health, interspersing your caffeinated drinks with plenty of plain water is the best approach, ensuring you get the fluid you need without the potential side effects of excessive caffeine.

American Institute for Cancer Research - Will coffee make me dehydrated?

Frequently Asked Questions

A moderate intake is generally considered around 3 to 4 cups per day for most healthy adults. This amount is typically not enough to cause a significant diuretic effect and allows for hydration.

Adding milk, especially lower-fat options, does not significantly impact hydration, as milk itself is a hydrating fluid. However, excessive sugar can cause a stronger diuretic effect and adds unnecessary calories, so it's best to limit or avoid it for maximum hydration.

Signs of dehydration include darker-colored urine, headaches, fatigue, dizziness, and dry mouth. Thirst is also a sign, but it means you are already experiencing mild dehydration.

No, most herbal teas are caffeine-free and are just as hydrating as plain water. They can be an excellent alternative for meeting fluid goals without the stimulating effects of caffeine.

This is the mild diuretic effect of caffeine. If you are a regular consumer, your body adapts, and the fluid loss is minimal. To counteract this, simply ensure you are also drinking plenty of plain water throughout the day.

Green tea does have mild diuretic properties due to caffeine, which can help increase urine output and potentially reduce mild water retention. It is not as powerful as prescription diuretics, but it can contribute positively.

Yes, it does. Regular, habitual caffeine consumers develop a tolerance, meaning the diuretic effect is less pronounced compared to someone who rarely drinks caffeinated beverages. For those with lower tolerance, the fluid loss may be slightly more noticeable.