What happens if I only drink tea and no water? The surprising truth about hydration

October 14, 2025 •

3 min read

According to numerous studies, moderate amounts of caffeinated tea can be as hydrating as plain water. However, replacing all water intake with tea, especially in large quantities, raises significant health concerns, begging the question: What happens if I only drink tea and no water?

Quick Summary

The health implications of exclusively drinking tea involve managing caffeine intake, potential dehydration from excessive consumption, and risks associated with tannins, oxalate, and mineral absorption. Maintaining a balanced diet and fluid intake, including plain water, is critical.

Key Points

Moderate tea is hydrating: Consuming tea in moderation contributes to your total fluid intake, as the diuretic effect of caffeine is typically minor and is offset by the water content.
Excessive caffeine intake poses risks: High consumption of caffeinated tea can lead to side effects like anxiety, heart palpitations, and sleep disturbances.
Tannins affect mineral absorption: Compounds in tea can inhibit the body's absorption of iron and calcium, which is a concern for individuals with or at risk of nutrient deficiencies.
Plain water is non-negotiable: Water performs essential bodily functions that tea cannot, and it remains the purest and most fundamental source of hydration.
Consider herbal teas: Caffeine-free herbal teas are an excellent alternative for variety, offering hydration without the stimulant effects of caffeine.
Long-term risks exist: Replacing water entirely with tea over a long period can increase the risk of kidney stones and other health complications.

The Dual Nature of Tea: Hydrator and Potential Risk

Tea is a beloved beverage consumed globally, celebrated for its diverse flavors and antioxidant properties. While it contains water, making it hydrating in moderation, its other components mean it is not a pure replacement for water. The consequences of relying solely on tea for fluid intake depend heavily on the type of tea and the quantity consumed.

The Caffeine Conundrum

Most traditional teas (black, green, oolong) contain caffeine, a natural stimulant with a mild diuretic effect. This means it encourages the body to produce more urine. In small amounts, the diuretic effect is minimal and outweighed by the large water content of the tea. However, if you drink multiple cups of strong, caffeinated tea daily, this effect can become more pronounced. For habitual caffeine consumers, the body builds a tolerance that lessens the diuretic effect. For those not accustomed to it, or when consuming excessively, this can lead to:

Increased urination
Restlessness and anxiety
Disrupted sleep patterns
Increased heart rate and blood pressure

Herbal teas, on the other hand, are typically caffeine-free and are considered an excellent hydrating choice, comparable to plain water.

The Impact of Tannins and Oxalates

Tea contains compounds called tannins, which are responsible for its astringent taste. While generally harmless, tannins can bind to minerals like iron in the digestive tract, inhibiting their absorption. This can be a significant issue for individuals with or at risk of iron deficiency anemia. Therefore, consuming tea around mealtimes, especially iron-rich meals, is not recommended for those with absorption concerns.

Another compound found in tea, especially black tea, is oxalate. Excess consumption of oxalate, combined with insufficient intake of plain water, can increase the risk of developing kidney stones (specifically, calcium oxalate stones). The risk is elevated when tea is the primary fluid source, putting additional strain on the kidneys.

Nutritional Deficiencies and Oral Health

Plain water is essential for a multitude of bodily functions that tea cannot fulfill. It helps transport nutrients, regulate body temperature, and flush out toxins efficiently without adding any extra compounds. Relying exclusively on tea can lead to a lack of nutritional diversity from other fluids. Furthermore, some tea varieties, particularly strong black tea, can be acidic and potentially lead to dental erosion or stomach discomfort over time. Water, in contrast, helps maintain a healthy oral pH balance and ensures optimal oral hydration.

The Importance of Variety and Balance

For optimal health, it is essential to consume a variety of fluids. While tea can be a flavorful and beneficial part of your fluid intake, it should not completely replace plain water. A balanced approach involves incorporating water, herbal teas, and other low-sugar, non-caffeinated beverages into your diet.

Potential Signs of Over-Reliance on Caffeinated Tea

Persistent headaches
Increased anxiety or nervousness
Sleep disturbances
Dark yellow urine
Frequent heartburn or stomach upset
Fatigue despite adequate sleep

Water vs. Tea: A Comparison

To highlight the differences, the table below compares the key attributes of plain water and tea regarding hydration and overall health.


Feature	Plain Water	Tea (Caffeinated)	Tea (Herbal)
Purity	Purest form of hydration.	Contains caffeine, antioxidants, and tannins.	Contains antioxidants, lacks caffeine.
Diuretic Effect	None.	Mild effect at high doses, counteracted by fluid content at moderate doses.	None.
Nutrient Absorption	Does not inhibit absorption.	Tannins can inhibit iron and calcium absorption.	Generally does not inhibit absorption.
Kidney Stone Risk	Reduces risk by diluting minerals.	Potential increased risk from oxalates, especially without balancing fluids.	Low risk; often recommended for hydration.
Acidity	Neutral pH.	Can be acidic, potentially causing stomach upset.	Generally less acidic than black tea.
Overall Health	Foundation for all bodily functions.	Contains antioxidants and other beneficial compounds.	Offers hydration and various health benefits depending on herbs.

The Verdict: A Balanced Approach Is Best

In conclusion, while tea can contribute to your daily fluid intake, it is not an adequate replacement for plain water. Relying solely on tea, especially caffeinated varieties, carries risks associated with excessive caffeine and tannins, potential mineral absorption issues, and increased kidney stone risk. For optimal health, consider tea a beneficial supplement to your hydration strategy, not the entire plan. Incorporate a variety of caffeine-free and low-sugar beverages, and prioritize plain water to meet your body's fundamental needs.

For further reading on the hydrating effects of beverages, see this meta-analysis on caffeine and diuresis from the NIH Library: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4725310/.

Frequently Asked Questions

No, while tea is mostly water and can contribute to your hydration, it is not recommended to get all your fluid intake from tea. You should balance it with plain water to avoid the negative effects of excessive caffeine, tannins, and to ensure optimal nutritional balance.

No, not in moderate amounts. The water content of tea typically outweighs the mild diuretic effect of its caffeine. A significant dehydrating effect only occurs with a very high intake (more than 6-13 cups) of strong caffeinated tea in a short period.

Tannins are compounds found in tea that give it a dry, slightly bitter taste. For some individuals, they can interfere with the body's ability to absorb essential minerals like iron, potentially leading to a deficiency over time.

To reduce potential side effects, you can switch to decaffeinated or herbal teas, reduce your daily intake of strong caffeinated tea, and ensure you drink an adequate amount of plain water throughout the day to balance your fluid intake.

Yes, herbal teas are typically caffeine-free and are considered just as hydrating as water. They can be counted towards your daily fluid requirements.

Yes, prolonged and exclusive consumption of tea, especially black tea, combined with insufficient plain water intake, can increase the risk of kidney stones due to its oxalate content. Plain water is crucial for flushing out the minerals that can form stones.

It is generally recommended to limit your daily intake of caffeinated tea to no more than 4-5 cups (around 400 mg of caffeine) to avoid unwanted side effects like anxiety, restlessness, and insomnia.