Understanding Your Nutrition Diet: What Liquids Count Toward Water Intake?

October 25, 2025 •

5 min read

While plain water is often cited as the gold standard for hydration, a 2016 study published in The American Journal of Clinical Nutrition found that some beverages can be even more hydrating than water over a certain period. This surprising fact challenges the common assumption and makes us question: what liquids count toward water intake and contribute to our overall fluid needs?

Quick Summary

All beverages containing water contribute to daily fluid intake, including milk, coffee, tea, and juice. Some liquids offer superior, longer-lasting hydration due to electrolytes and nutrients, though options high in sugar or caffeine should be limited. Plain water remains the best, calorie-free choice for routine hydration.

Key Points

All Beverages Count: Nearly all liquids you drink, including milk, coffee, tea, and juice, contribute to your total daily fluid intake.
Milk Hydrates Longer: Milk can be more hydrating than plain water over time due to its electrolytes, proteins, and fats, which slow gastric emptying.
Caffeine Is Not Dehydrating (in Moderation): The mild diuretic effect of caffeine does not negate the hydrating effect of the water in moderate amounts of coffee and tea.
Water Is Still Best: Plain water is the most beneficial and calorie-free way to stay hydrated for most people and everyday situations.
Limit Sugary Drinks: While sodas and sweetened juices contain water, their high sugar content makes them poor choices for primary hydration.
Watery Foods Contribute: A significant portion of your daily hydration comes from water-rich foods like fruits, vegetables, and soups.

Demystifying Fluid Intake

For many years, the advice was simple: drink eight glasses of water a day. While this remains a helpful guideline, the science of hydration is more nuanced. Our bodies obtain fluid not only from water but from nearly every liquid we consume, as well as many water-rich foods. The key lies in understanding the composition of these liquids and how they affect our bodies. Factors like sugar, fat, protein, and electrolytes all play a role in how efficiently and sustainably a beverage hydrates us.

The Beverage Hydration Index (BHI)

To scientifically evaluate different drinks, a measurement called the Beverage Hydration Index (BHI) was developed. It compares the fluid retention of various beverages to that of plain water over a four-hour period. A BHI greater than one indicates that more fluid was retained than when consuming the same volume of plain water. This research offers a fascinating look at how different components in drinks influence our body's hydration levels.

The Hydration Hierarchy: Ranking Common Liquids

While water is the undisputed best choice for most situations due to its zero calories and additives, other fluids offer unique hydrating properties. Knowing their benefits and drawbacks can help you make better choices for your overall nutrition diet.

The Unexpected Advantage of Milk

Several studies have shown that milk can be more hydrating than plain water for a sustained period. This is because milk contains a natural blend of sugar (lactose), protein, and fat, which slows the emptying of fluid from the stomach. It also contains sodium, an electrolyte that helps the body retain water more effectively, reducing urine output. For children, athletes, or anyone needing prolonged hydration, milk is an excellent option.

The Truth About Caffeinated Beverages

For a long time, it was a popular belief that caffeinated drinks like coffee and tea were dehydrating. Modern research has largely debunked this myth. While caffeine is a mild diuretic, the water content of these beverages far outweighs its diuretic effect when consumed in moderation. The NHS confirms that tea and coffee count toward daily fluid intake. However, excessive consumption (e.g., more than four cups of coffee per day) can still lead to increased urination in some people. The primary concern with these drinks is not dehydration but the potential for added sugars and calories.

The Role of Juices and Sports Drinks

Fruit and vegetable juices and sports drinks are also effective hydrating fluids because they are primarily composed of water. Sports drinks, in particular, are formulated to replace fluids and electrolytes lost during intense or prolonged physical activity. The main issue with both is their high sugar content. While 100% fruit juice offers vitamins and minerals, the British Nutrition Foundation recommends limiting intake to a small glass (150ml) per day to protect teeth and manage sugar consumption. For most people, water is sufficient for rehydration after exercise.

Limiting Sugary and Carbonated Drinks

Sugary sodas, energy drinks, and other sweetened beverages contain large amounts of simple sugars and empty calories. While they technically contribute to your fluid intake, they are not a recommended source of hydration. High sugar loads can actually pull water from the body into the intestine to aid dilution, making them less efficient for hydration. Overconsumption is linked to weight gain and increased risk of diseases like diabetes.

A Comprehensive List of Liquids for Hydration

Plain Water: The best choice for consistent, calorie-free hydration.
Milk (Dairy or Plant-Based): Excellent for longer-term hydration due to electrolytes and nutrients. Choose lower-fat varieties for a healthier profile.
Coffee and Tea (Unsweetened): Count toward fluid intake in moderation. Be mindful of added sugars and creams.
Herbal Tea: Caffeine-free and hydrating, often with added antioxidant benefits.
Fruit-Infused Water: A great way to add flavor without sugar. Try lemon, cucumber, or mint.
Smoothies and Soup: Water-rich foods contribute significantly to daily fluid intake. Many fruits, vegetables, and broths are almost 100% water by weight.
100% Fruit Juice: Hydrating but should be limited due to high natural sugar content.

Beverage Hydration Comparison Table


Beverage	Primary Hydration Source	Calories & Sugar	Electrolytes	Best for...
Plain Water	Pure water	0	None	Everyday hydration, budget-friendly
Milk	Water, sugar, fat, protein	Varies by fat content	Sodium, Potassium, etc.	Sustained hydration, post-exercise recovery
Coffee/Tea (Unsweetened)	Water	Low	None	Aiding fluid intake, moderate consumption
Herbal Tea	Water	0	None	Calorie-free hydration with flavor
100% Fruit Juice	Water	High	Potassium, etc.	Vitamin boost (limit intake)
Sports Drink	Water, sugar, electrolytes	High	Sodium, Potassium, etc.	Intense, prolonged exercise
Soda	Water	High (added sugar)	None	Occasional treat, not for hydration

How to Maximize Hydration from All Sources

Start with Water: Make plain water your primary fluid source throughout the day. It's the most efficient and healthiest option.
Add Flavor Naturally: If you dislike plain water, infuse it with fruits like lemon, berries, or cucumber. You can also opt for herbal teas.
Use Milk Strategically: Incorporate milk into your diet, especially after a workout, to benefit from its superior and sustained hydrating properties.
Balance Caffeinated Drinks: Enjoy coffee and tea in moderation. Remember that adding lots of sugar and cream can negate their health benefits.
Eat Water-Rich Foods: Incorporate foods like watermelon, strawberries, lettuce, and soups into your meals. These can provide a significant portion of your daily fluid needs.
Limit Sugar-Sweetened Beverages: Reserve sodas and sugary juices for occasional treats, and never rely on them for essential hydration. Diluting juice with water can be a better option.

Conclusion

In the grand scheme of a healthy nutrition diet, understanding what liquids count toward water intake is crucial. While water remains the most important liquid, other beverages like milk, tea, and even moderate amounts of coffee contribute to your daily fluid goals. By being mindful of sugar and calorie content, and prioritizing water-rich options, you can maintain optimal hydration and support your overall health. The right balance ensures you stay refreshed and energized, regardless of your drink preference.

For more information on the hydration effects of various beverages, you can consult studies like the one published in The American Journal of Clinical Nutrition which outlines the Beverage Hydration Index.

Frequently Asked Questions

Yes, in moderation, coffee and tea do count towards your daily fluid intake. The water content of these beverages far outweighs the mild diuretic effect of caffeine, meaning they contribute positively to your hydration.

Research has shown that milk, particularly skim milk, can be more hydrating than water over a sustained period. This is because milk contains electrolytes, protein, and fat, which help the body retain fluid more effectively.

Technically, you can, as these drinks are mostly water. However, they are not recommended for hydration due to their high sugar content and calories. High sugar loads can be counterproductive and are linked to health issues.

Fruit juices contain water and can be hydrating, but they should be consumed in moderation. They are high in natural sugar, which can lead to excessive calorie intake and tooth decay if overconsumed.

Sports drinks are designed to replace fluids and electrolytes for athletes engaging in intense, prolonged exercise. For most people, they are unnecessary and just add extra sugar. Energy drinks often contain high levels of caffeine and sugar, making them poor hydration choices.

Approximately 20-30% of your daily fluid intake comes from foods, especially water-rich fruits and vegetables like watermelon, lettuce, tomatoes, and soups.

No, adding natural flavorings like a slice of lemon or a sprig of mint does not negatively affect water's hydrating properties. It is a great way to make plain water more palatable without adding sugar or calories.