Water dethroned: these 5 drinks hydrate even better, according to science
Water: vital, yes — but not unbeatable
Let’s get one thing straight: no one is denying how essential water is. Nearly all living things depend on it to function and survive — it’s the foundation of life itself. Still, when we look at the facts, is it really the drink that hydrates us best?
It seems obvious that the answer would be yes. If you’re thirsty, drink water — problem solved, right? Not so fast. Chemically speaking, the story is a little more complex. The formula H₂O refers to distilled water, not the kind we actually drink. Tap and bottled waters contain trace minerals like calcium, magnesium, and potassium — which, as it turns out, make a big difference.
Our bodies are accustomed to mineral water, but drinking distilled water over time can upset our balance of electrolytes — the charged minerals that regulate chemical reactions, nerve function, and fluid balance. That’s why the drinks that hydrate best are those rich in electrolytes.
You might think first of an oral rehydration solution — those powdered mixes often given to babies after a bout of gastroenteritis. They’re designed to replace lost water, salts, and nutrients, helping the body recover its balance quickly.
The top five most hydrating drinks
With an endless array of beverages — from fruit juices to sports drinks to sodas — it’s hard to tell which ones actually hydrate best. Since hydration power isn’t listed on labels, researchers at the University of St. Andrews decided to test it scientifically.
They evaluated how quickly different drinks hydrate the body and how long the effect lasts. The key discovery? Drinks that contain small amounts of lactose, protein, or fat help the body retain fluids longer — because these components slow down how fast water exits the system.
The results were surprising. Skim milk ranked first, with a Beverage Hydration Index (BHI) of 99%, tying with oral rehydration solutions and whole milk. Orange juice came next, with a BHI of 95%, just edging out water itself.
Here’s the ranking:
- Skimmed milk
- Oral rehydration solution (for children, athletes, or seniors)
- Whole milk
- Orange juice
- Water
Yes, plain water only comes fifth — though researchers caution that the hydration differences are minor. This doesn’t mean you should start swapping water for milk every day. But for groups like older adults, infants, or people who struggle to drink large amounts of liquid, these alternatives might provide better hydration support.
In short: water is still life’s essential liquid — but when it comes to sheer hydration, science says it might not always be number one.