What's the most hydrating drink? The science-backed guide

According to a 2016 study in the American Journal of Clinical Nutrition, some common beverages actually hydrate the body more effectively and for longer than plain water. The key lies in their nutrient composition, which helps the body retain fluid more efficiently. So, what's the most hydrating drink, and how does it stack up against simple H2O?

Quick Summary

This guide reveals the surprising science behind which drinks offer superior hydration. It examines how electrolytes, carbohydrates, and protein content influence fluid retention, comparing everyday choices like water, milk, and sports drinks to reveal the most effective options for long-lasting hydration.

Key Points

• Skim Milk is a Top Hydrator: Studies show skim and whole milk often outperform plain water for long-lasting rehydration due to their content of water, electrolytes, and carbohydrates.

• Electrolytes are Key: For intense exercise or illness, electrolytes like sodium and potassium are crucial for effective fluid retention, which is why oral rehydration solutions rank highly.

• Water is Best for Daily Needs: For most people and routine activity, plain water is the ideal, calorie-free choice for maintaining proper hydration.

• Sugary Drinks can Hinder Hydration: High-sugar beverages like soda can actually pull water from your body, making them less effective for rehydration compared to water or milk.

• Coffee isn't as Dehydrating as Thought: Moderate consumption of coffee does not lead to dehydration in regular drinkers, as the water content largely offsets the mild diuretic effect of caffeine.

• Monitor Your Urine Color: A simple and effective way to check your hydration level is by the color of your urine; pale yellow indicates adequate hydration.

• Make Your Own Electrolyte Drink: A homemade solution with water, salt, and a splash of 100% juice is a great alternative to store-bought sports drinks.

Is Water Truly the King of Hydration?

For years, water has been crowned the undisputed champion of hydration. For day-to-day fluid intake, it remains the gold standard: it's calorie-free, readily available, and perfectly sufficient for maintaining fluid balance in most individuals. However, the concept of 'most hydrating' can be broken down further to consider specific circumstances, such as intense exercise or illness. This is where the nuanced science of fluid retention comes into play.

The Beverage Hydration Index (BHI)

In a groundbreaking 2016 study by researchers at Scotland's St. Andrews University, the hydrating effects of 13 different beverages were evaluated, leading to the creation of the Beverage Hydration Index (BHI). This index measures how much fluid is retained in the body over a period of hours after consumption. The results showed that plain still water and sparkling water were not the most hydrating beverages on the list. The top spot was taken by skim and whole milk, followed closely by oral rehydration solutions.

What Makes Some Drinks More Hydrating?

Several factors contribute to a beverage's hydrating power, most notably its electrolyte, carbohydrate, and protein content.

• Electrolytes: Minerals like sodium and potassium play a crucial role in maintaining fluid balance. When lost through sweat, they need to be replenished. Sodium, in particular, acts like a sponge, helping the body hold onto water and reducing the amount of urine produced.
• Carbohydrates: A small amount of sugar can slow the emptying of fluid from the stomach, allowing for a more gradual and prolonged absorption of water into the bloodstream. However, beverages with very high concentrations of sugar, like many sodas, can be counterproductive and may draw water out of the body through osmosis.
• Protein and Fat: Found in milk, protein and fat also contribute to slower gastric emptying, which prolongs the hydration effect. This slower, more sustained release of fluid is a key reason milk consistently ranks high for rehydration.

A Closer Look at Top Hydrating Drinks

Based on scientific findings, here are some of the most effective drinks for staying hydrated, particularly in situations of greater fluid loss.

• Milk (Skim or Whole): Milk is arguably the most hydrating drink for effective post-exercise rehydration. Its combination of water, electrolytes (sodium and potassium), carbohydrates (lactose), and protein allows the body to absorb and retain fluid more efficiently than plain water. It's a particularly great option for athletes looking for both rehydration and muscle recovery.
• Oral Rehydration Solutions (ORS): Designed for treating dehydration caused by illness, such as vomiting or diarrhea, ORS formulas are highly effective. They contain a precise balance of water, glucose, and electrolytes (sodium, potassium, and chloride) to maximize fluid retention and absorption.
• Coconut Water: Often marketed as a natural sports drink, coconut water is rich in potassium and contains moderate levels of other electrolytes. It's a lower-sugar alternative to many commercial sports drinks, making it a good choice for replenishing fluids after moderate exercise.
• Fruit Juice (100%): Juices like orange or watermelon contain water, natural sugars, and electrolytes like potassium. In moderation, they can contribute to effective hydration, but it's important to choose 100% juice and be mindful of the calorie and sugar content.

Comparison of Common Drinks for Rehydration

To help you choose the right drink for your needs, here is a breakdown of how several common beverages compare on a scale of hydration effectiveness, based on scientific findings.

Beverage	Primary Hydration Mechanism	Key Advantages	When to Choose	Potential Drawbacks
Plain Water	Water absorption	Calorie-free, readily available, sufficient for daily needs.	Everyday hydration, low-intensity activity.	Lacks electrolytes for optimal fluid retention after heavy sweat loss.
Milk (Skim/Whole)	Electrolytes, carbs, protein slow gastric emptying.	Superior fluid retention, aids muscle recovery.	Post-exercise rehydration, recovery from dehydration.	Higher calories than water, unsuitable for lactose-intolerant individuals.
Oral Rehydration Solution	Precise electrolyte balance for maximum absorption.	Clinically proven for treating dehydration from illness.	When recovering from severe fluid loss (illness, heat exhaustion).	Often contains sugar and can be expensive.
Coconut Water	Natural electrolytes (potassium).	Lower in sugar than many sports drinks, refreshing taste.	Moderate exercise, everyday electrolyte replenishment.	Lower sodium content than sports drinks, may not be ideal for heavy sweat loss.
Sports Drink	Electrolytes (sodium, potassium), carbs.	Quick energy boost, formulated for enhanced absorption.	Prolonged, intense exercise (>1 hour).	High sugar and calorie content in many versions.

Practical Hydration Strategies for Optimal Health

While the science highlights the superior rehydration potential of some drinks in specific scenarios, your overall hydration strategy should be multifaceted. For the average person, balancing your fluid intake is key. If you're physically active or living in a hot climate, a more targeted approach is necessary.

• Listen to your body: While thirst can signal a mild state of dehydration, it is not always the most reliable indicator, particularly during strenuous exercise. Other signs like dark urine, fatigue, and muscle cramps are also crucial to recognize.
• Infuse your water: For those who find plain water unappealing, adding slices of fruit like lemon, cucumber, or watermelon can improve taste without adding excess sugar or calories.
• Consider your diet: A significant portion of our daily fluid intake comes from food, especially water-rich fruits and vegetables like watermelon, strawberries, and cucumbers. Broths and soups are also excellent sources of fluid and electrolytes.
• Monitor urine color: A simple yet effective way to gauge hydration is to check the color of your urine. A pale yellow or straw-like color generally indicates good hydration, while a darker color suggests you need to increase your fluid intake.
• Plan around activity: If you plan on engaging in intense or prolonged exercise, strategic rehydration with a drink containing electrolytes and carbohydrates can prevent performance decline.

Conclusion: The Final Verdict on the Most Hydrating Drink

The question of what's the most hydrating drink has a nuanced answer: it depends on the context. For most day-to-day scenarios, plain water is sufficient and the healthiest choice. However, for effective rehydration after significant fluid loss—like from intense exercise or illness—scientifically backed evidence shows that beverages like skim milk and oral rehydration solutions are superior to water due to their electrolyte, carbohydrate, and protein content. For athletes, sports drinks can provide a useful boost of energy and electrolytes, while natural alternatives like coconut water or 100% fruit juice can serve a similar purpose in moderation. By understanding the science behind fluid absorption, you can make informed choices to optimize your hydration for any situation. The ultimate takeaway is that while water is essential, having a variety of hydrating options can be a smart strategy for overall health and wellness.

Note: Before making significant changes to your hydration routine, especially in response to a medical condition or intense athletic training, it is always best to consult with a healthcare provider or a registered dietitian.

References

• Harvard Health. (2022, November 14). When replenishing fluids, does milk beat water? Harvard Health Publishing. https://www.health.harvard.edu/blog/when-replenishing-fluids-does-milk-beat-water-202211142849
• Healthline. (2018, May 13). Should You Drink Sports Drinks Instead of Water? Healthline Media. https://www.healthline.com/nutrition/sports-drinks
• The Nutrition Source. (2025, February 26). How Much Water Do You Need? Harvard T.H. Chan School of Public Health. https://nutritionsource.hsph.harvard.edu/water/
• Gundersen Health System. (2025, February 19). Water or electrolyte drinks: What's better for athletes? Gundersen Health System. https://www.gundersenhealth.org/health-wellness/eat-move/water-or-electrolyte-drinks-whats-better-for-athletes
• CBS News Boston. (2023, May 9). Milk is a better drink for hydration than water, study finds. CBS News. https://www.cbsnews.com/boston/news/milk-hydration-better-than-water-study-drinks-scotland/
• GonnaNeedMilk. (n.d.). Milk vs Sports Drinks. GonnaNeedMilk. https://gonnaneedmilk.com/articles/milk-vs-sports-drinks/
• Got Milk?. (n.d.). Hydrates better than Water. Got Milk?. https://www.gotmilk.com/hydrates-better-than-water/
• Benshosan, A. (2025, July 21). Milk Might Actually Be More Hydrating Than Water—Here's What the Science Says. EatingWell. https://www.eatingwell.com/hydration-benefits-milk-11775549
• NIB. (n.d.). Water vs. Electrolytes: What Is Best For Hydration? The Checkup. https://www.nib.com.au/the-checkup/everyday-health/general-health-guides-and-faqs/water-versus-electrolytes
• Healthline. (2025, June 11). 8 Electrolytes Drinks to Add to Your Wellness Routine. Healthline Media. https://www.healthline.com/nutrition/electrolytes-drinks
• Foodie. (2025, June 26). How Orange Juice Is Actually More Hydrating Than Water. Foodie. https://www.foodie.com/1893074/why-orange-juice-more-hydrating-water/
• NHS. (n.d.). Water, drinks and hydration. NHS. https://www.nhs.uk/live-well/eat-well/food-guidelines-and-food-labels/water-drinks-nutrition/
• Bloom Insure. (n.d.). The best and worst drinks to keep you hydrated. Bloom Insure. https://bloom.insure/the-best-and-worst-drinks-to-keep-you-hydrated/
• Better Health Channel. (n.d.). Exercise - the low-down on hydration. Better Health Channel. https://www.betterhealth.vic.gov.au/health/healthyliving/Exercise-the-low-down-on-water-and-drinks
• Mayo Clinic Health System. (2022, September 29). Water: Essential for your body. Mayo Clinic Health System. https://www.mayoclinichealthsystem.org/hometown-health/speaking-of-health/water-essential-to-your-body-video
• Good Food. (2024, September 2). How to make an electrolyte drink. BBC Good Food. https://www.bbcgoodfood.com/health/fitness/how-to-make-an-electrolyte-drink
• NIH. (2014, October 16). The Hydration Equation: Update on Water Balance and Cognitive Performance. National Institutes of Health. https://pmc.ncbi.nlm.nih.gov/articles/PMC4207053/
• The Nutrition Source. (2025, May 20). Do I need electrolyte drinks? Harvard T.H. Chan School of Public Health. https://nutritionsource.hsph.harvard.edu/electrolyte-drinks/
• GoodRx. (2025, January 11). The Best Hydrating Drinks High in Electrolytes and Nutrients. GoodRx. https://www.goodrx.com/well-being/diet-nutrition/best-drinks-for-hydration
• Florida Citrus. (n.d.). Hydration and Florida Orange Juice. Florida Department of Citrus. https://www.floridacitrus.ca/oj/health-nutrition/hydration/

Article Content Continued...

Factors Affecting Your Hydration Needs

Your personal hydration requirements are not static; they fluctuate based on a variety of physiological and environmental factors. Ignoring these can lead to under-hydration, even if you are drinking frequently.

• Physical Activity Level: The more you exercise, the more you sweat and lose fluids. Athletes engaging in prolonged or high-intensity activity, especially in warm conditions, will have significantly higher fluid and electrolyte needs.
• Climate: High temperatures and humidity increase sweat rates, while high altitude can increase respiratory water loss. Both conditions necessitate increased fluid intake to maintain hydration.
• Dietary Intake: Foods contribute to your overall fluid balance, but some substances can affect it. High salt or protein intake, for example, can increase fluid needs. Conversely, a diet rich in fruits and vegetables adds a significant amount of water.
• Medical Conditions: Certain health issues like diabetes, kidney disease, or a fever can alter fluid balance. Diarrhea and vomiting, in particular, lead to rapid fluid and electrolyte loss and require specialized rehydration.
• Age and Body Composition: Body water percentage changes with age and differs based on body fat and muscle mass. As we age, our total body water decreases, and a higher muscle mass corresponds to a higher body water percentage.

The Role of Water vs. Electrolyte Drinks

Understanding the distinction between water and electrolyte drinks is crucial for making the best choice for a given situation. Plain water is excellent for maintaining normal hydration during sedentary periods or low-intensity exercise. Electrolyte drinks, however, are specifically formulated to replace minerals lost through heavy sweating or illness. This is particularly important for athletes who sweat heavily or for individuals recovering from bouts of illness with significant fluid loss. The inclusion of electrolytes in these beverages aids in quicker and more effective reabsorption of fluid, preventing conditions like hyponatremia (low blood sodium) which can occur from overconsumption of plain water without adequate electrolyte replacement.

Creating Your Own Hydration Solutions

For those who wish to avoid the sugar and additives in commercial sports drinks, creating a homemade electrolyte beverage is a simple and effective option. A basic solution can be made with water, a pinch of salt (for sodium and chloride), and a splash of 100% fruit juice (for potassium and carbohydrates). Adding fruit-infused flavors can also make regular water more appealing, encouraging greater intake throughout the day. For instance, a simple combination of cucumber, mint, and a slice of lime can transform plain water into a refreshing, subtly flavored beverage. Similarly, a smoothie made with Greek yogurt, a banana, and a handful of spinach can be a nutrient-dense and hydrating meal replacement.

Frequently Asked Questions

Is milk or water more hydrating?

Scientific studies show that skim and whole milk can be more hydrating than plain water for longer periods. This is because milk contains electrolytes, carbohydrates, and protein, which slow fluid emptying from the stomach and promote greater fluid retention in the body.

When is an electrolyte drink better than water?

Electrolyte drinks are superior to water for rehydration after significant fluid loss. This includes periods of intense or prolonged exercise, especially in hot weather, and recovery from illnesses involving vomiting or diarrhea, where electrolytes are rapidly depleted.

Can I get enough hydration from food?

Foods, particularly water-rich fruits and vegetables like watermelon and cucumbers, contribute significantly to your daily fluid intake. In fact, a healthy diet can provide 20–30% of your total water intake.

Does coffee or tea dehydrate you?

Despite the long-standing myth, moderate consumption of caffeinated drinks like coffee and tea does not cause dehydration in regular drinkers. The water content is enough to offset caffeine's mild diuretic effect, so it can contribute to your daily fluid intake.

How can I tell if I'm dehydrated?

A key indicator of hydration is the color of your urine. Pale yellow urine suggests adequate hydration, while a darker color is a sign that you need more fluids. Other symptoms include fatigue, headaches, dry mouth, and confusion.

Are all fruit juices hydrating?

100% fruit juices, like orange juice, can be hydrating due to their high water content and electrolytes such as potassium. However, many store-bought juices contain high levels of added sugar, which can be counterproductive, so it is important to check the label.

Is it better to make my own electrolyte drink?

Making your own electrolyte drink allows you to control the sugar and additive content found in many commercial sports drinks. A simple solution can be created with water, a pinch of salt, and a small amount of fruit juice.