Water is the simplest and most effective drink for staying hydrated, but it’s not your only option. Milk, fruit juice, coconut water, and even coffee all contribute to your daily fluid intake. The National Academy of Medicine recommends about 13 cups (104 ounces) of total daily fluids for men and 9 cups (72 ounces) for women, though roughly 20% of that typically comes from food rather than beverages.
Water Is the Baseline, Not the Only Option
Plain water is calorie-free, widely available, and does the job. But if you find it boring or struggle to drink enough, you have real alternatives. A study from Loughborough University developed a Beverage Hydration Index that ranked common drinks by how well the body retains their fluid over several hours. The results were surprising: skim milk and whole milk kept people hydrated longer than plain water, performing roughly on par with oral rehydration solutions designed for that exact purpose. Orange juice scored about equal to water, and slightly better at certain time points.
The reason milk outperforms water comes down to its natural composition. It contains small amounts of sodium, potassium, and protein, which slow the rate at which fluid passes through your system. That doesn’t mean you should replace water with milk, but it does mean a glass of milk at breakfast genuinely counts toward hydration.
Where Coconut Water and Sports Drinks Differ
Coconut water and sports drinks like Gatorade both contain electrolytes, but their profiles are almost opposite. A cup of coconut water has about 404 mg of potassium and 64 mg of sodium. A cup of Gatorade flips that ratio: 97 mg of sodium and just 37 mg of potassium. For everyday hydration, coconut water’s potassium-rich profile works well. But during prolonged, heavy sweating (long runs, outdoor labor in heat), sodium is what your body loses most, which is why sports drinks are formulated the way they are.
If you’re not exercising intensely for more than an hour, you likely don’t need either one. Water or a glass of milk will cover you. Sports drinks add sugar and calories that most people don’t need for a typical workout.
Coffee and Tea Still Hydrate You
Caffeine is technically a diuretic, meaning it increases urine production. But the fluid in a cup of coffee or tea more than compensates for any extra urine output at typical caffeine levels. The Mayo Clinic notes that most research shows caffeinated drinks balance out their own diuretic effect. So your morning coffee counts toward your daily fluid intake. It’s not dehydrating you.
That said, heavily sweetened coffee drinks or energy drinks with very high caffeine levels are a different story. The sugar adds empty calories, and extreme caffeine doses (above 400-500 mg) can tip the balance toward fluid loss. A few cups of regular coffee or tea per day, though, are perfectly fine for hydration.
Foods That Count Toward Your Fluid Intake
About 20% of your daily water comes from food, not drinks. Many fruits and vegetables are nearly 100% water by weight: watermelon, strawberries, cantaloupe, cucumbers, cabbage, and squash all fall into this category. A large salad or a few servings of fruit can meaningfully contribute to your hydration without you drinking a single extra glass of water. Soups, yogurt, and oatmeal made with milk or water also add up.
This is worth keeping in mind if you feel like you never drink “enough.” If your diet includes plenty of fresh produce and water-rich foods, your actual fluid needs from beverages are lower than the headline numbers suggest.
The 8-Glasses Rule Is a Rough Guide
The advice to drink eight 8-ounce glasses of water a day (64 ounces total) is easy to remember, but it’s not based on strong science. For some people it’s reasonable, for others it’s too little or too much. The actual recommendation from the National Academies ranges from 92 to 124 ounces of total water daily for adults in a temperate climate, and that includes water from food and all beverages. Your individual needs shift based on body size, activity level, climate, and whether you’re pregnant or breastfeeding.
Rather than counting glasses, a more practical approach is checking the color of your urine. Pale, light yellow urine means you’re well hydrated. Slightly darker yellow suggests you need a glass or two of water. Medium to dark yellow, especially in small amounts with a strong smell, signals real dehydration that needs immediate attention. One caveat: certain foods (like beets), vitamins (especially B vitamins), and medications can change urine color even when you’re perfectly hydrated.
Older Adults Need to Drink Before They Feel Thirsty
One of the most important things to know about hydration is that thirst becomes a less reliable signal as you age. Research shows that the thirst response to dehydration is consistently reduced in older adults, driven by changes in the hormonal systems that regulate fluid balance. The brain’s mechanisms for detecting dehydration and triggering the urge to drink simply become less sensitive over time.
This isn’t a minor inconvenience. During heat waves, significant illness and death among elderly populations is primarily caused by inadequate water intake, not by the heat alone but by the failure of thirst to keep up with the body’s actual needs. If you’re over 65, or you’re looking out for someone who is, building hydration into a daily routine (rather than relying on thirst) is one of the most practical health measures available. Keeping a water bottle visible, drinking a glass with every meal, and choosing water-rich foods all help close the gap.
What to Drink in Practice
- Water remains the best default. It’s free of sugar, calories, and additives.
- Milk (skim or whole) hydrates more effectively than water over several hours, thanks to its natural electrolytes and protein.
- Coffee and tea count toward your daily intake at normal consumption levels.
- Coconut water is a good potassium source for general hydration but low in sodium compared to sports drinks.
- Sports drinks are useful during prolonged, intense exercise lasting over an hour, especially in heat. Otherwise, they add unnecessary sugar.
- Fruit juice hydrates about as well as water but comes with calories. Diluting it with water gives you flavor without the sugar load.
- Soda and sweetened drinks do provide fluid, but the high sugar content makes them a poor everyday hydration choice.
The best hydration strategy is the one you’ll actually follow. If plain water bores you, adding sliced fruit, switching to sparkling water, or alternating with tea keeps you drinking consistently throughout the day. Consistency matters more than perfection.