Understanding What Is the Most Hydrating Thing You Can Drink?

October 18, 2025 •

3 min read

In a 2015 study in The American Journal of Clinical Nutrition, researchers discovered that while water is effective for quick hydration, certain beverages with added nutrients, like milk, are more effective for long-term fluid retention. This finding challenges the common assumption that plain water is universally the best option, leading many to question, what is the most hydrating thing you can drink?.

Quick Summary

The most hydrating drink is not always water. Beverages containing electrolytes, protein, and fat can slow digestion and reduce urine output, leading to better long-term fluid retention. Hydration needs depend on activity level and environmental conditions.

Key Points

Water is not the single most hydrating drink: While effective for quick thirst, its fluid is eliminated faster than that from nutrient-rich alternatives like milk.
Milk offers superior, prolonged hydration: Due to its natural lactose, protein, fat, and electrolytes, milk delays gastric emptying and promotes better long-term fluid retention.
Electrolyte solutions are ideal for recovery and illness: Specialized oral rehydration solutions are most effective for restoring fluid balance after illness or significant fluid loss during intense exercise.
Hydration from food is a powerful tool: Watermelon, cucumbers, and other fruits and vegetables contain high water content and contribute significantly to overall hydration.
The best choice depends on the situation: For everyday hydration, plain water is sufficient, while milk, ORS, or sports drinks may be more beneficial after intense activity or illness.
Balanced intake is key: Combining plain water with water-rich foods and other beverages is the most effective strategy for optimal and sustained hydration for most people.
Excessive urination can indicate poor fluid retention: If you drink a lot of water and produce clear urine shortly after, it means the fluid is not being retained efficiently.

Debunking the Water Myth: Why Nutrients Matter

While water is often considered the standard for hydration, research indicates that beverages with specific nutrient profiles can be more effective for prolonged fluid retention. Plain water is absorbed quickly but also rapidly eliminated through urine. Drinks containing electrolytes, protein, and fat slow down gastric emptying, allowing the body more time to absorb and retain fluids.

Milk, for instance, has been shown to be more hydrating than plain water over several hours. Its combination of natural sugars (lactose), protein, fat, and electrolytes like sodium helps the body maintain fluid balance and hold onto water longer. This makes milk particularly beneficial for rehydration after exercise, when electrolytes are lost through sweat.

The Role of Electrolytes and Rehydration Solutions

Oral rehydration solutions (ORS) are highly effective for hydration, especially when dehydration is caused by illness. These solutions are formulated with water, glucose, and electrolytes (sodium and potassium) to enhance water absorption in the small intestine and promote fluid retention. While ORS is crucial for significant fluid loss, less concentrated electrolyte drinks can be suitable for post-exercise recovery.

Top Hydrating Beverages and Foods

A varied approach to hydration, including both fluids and water-rich foods, is recommended. Some top hydrating options include:

Skim and Full-Fat Milk: More hydrating than water due to their nutrient content.
Oral Rehydration Solutions: Designed for rapid absorption and retention, especially during illness or heavy sweating.
Watermelon: Over 90% water and contains electrolytes and vitamins.
Cucumber: Around 96% water, providing fluids, vitamins, and minerals.
Coconut Water: A natural source of electrolytes like potassium.
Broth: Contains high water content and electrolytes, helpful for replenishing fluids.
Fruits and Vegetables: Many are over 85% water and contribute to daily fluid intake.

The Hydration Index and Individual Needs

The Beverage Hydration Index (BHI) measures how well drinks maintain hydration over time, emphasizing fluid retention. However, hydration needs are individual, varying based on factors like activity level and environment. For most people, consuming plain water throughout the day, especially with meals, is sufficient and healthy. Drinking water with meals aids in slower gastric emptying, supporting natural hydration.

Hydration Comparison: Different Drinks for Different Needs


Feature	Plain Water	Skim Milk	Sports Drink	Oral Rehydration Solution (ORS)
Best for...	Everyday hydration, quick thirst quenching	Post-exercise recovery, sustained hydration, muscle repair	Intense, prolonged exercise (over 1 hour)	Severe dehydration from illness (diarrhea, vomiting)
Key Components	Water	Water, lactose, protein, fat, sodium, potassium, calcium	Water, carbohydrates, sodium, potassium (can have added sugar)	Water, glucose, sodium, potassium
Fluid Absorption	Rapid	Slower (due to nutrients)	Moderate (sugar aids absorption)	Rapid (designed for max absorption)
Fluid Retention	Lower (quicker urination)	Higher (nutrients slow gastric emptying)	Lower than milk/ORS for rest, but effective during exercise	Very High (optimal electrolyte balance)
Calorie Content	Zero	Moderate	Variable (often high from sugar)	Low

Conclusion: The Most Hydrating Thing You Can Drink Varies

In conclusion, while water is essential, it may not be the most hydrating drink for long-term fluid retention compared to beverages with electrolytes and macronutrients like milk or ORS, which are beneficial for post-exercise recovery or illness. A balanced approach incorporating water, water-rich foods, and other drinks as needed is optimal for most individuals. The best choice depends on personal needs, activity levels, and circumstances.

Learn more about the science of hydration and exercise from the British Nutrition Foundation.

Frequently Asked Questions

Studies have found that milk is more hydrating than water for prolonged fluid retention, thanks to its content of lactose, protein, fat, and electrolytes which slow down gastric emptying.

For most people, water is sufficient. However, for intense, prolonged exercise lasting over an hour, sports drinks can be more effective than water as they replace electrolytes and provide carbohydrates for energy.

The quickest way to effectively rehydrate is by using an oral rehydration solution (ORS). These solutions are specifically formulated with an optimal balance of electrolytes and glucose for rapid absorption, especially in cases of illness-related dehydration.

Coconut water is a good source of potassium and other electrolytes, offering a hydrating alternative to plain water. While effective, it may not be as hydrating as milk or a specialized ORS for long-term fluid retention.

While rare, it is possible to drink too much water. This can lead to hyponatremia, a condition where sodium levels in the blood become dangerously low, especially in athletes during long-endurance events.

Yes, contrary to popular belief, moderate amounts of caffeinated beverages like tea and coffee can contribute to your daily fluid intake. The diuretic effect is mild and typically does not outweigh the fluid contribution.

Milk's effectiveness comes from its nutrient composition. It contains lactose, protein, and fat, which slows digestion, allowing the body to absorb and retain fluids for a longer period. Its natural sodium content also helps the body hold onto water.

Numerous foods, particularly fruits and vegetables, have a high water content. Excellent examples include watermelon (92% water), cucumbers (96% water), lettuce (96% water), and strawberries (91% water).