Neither cold water nor room temperature water is objectively “better” for you. Both hydrate you equally well, and the best temperature is mostly the one that gets you to drink more. That said, each temperature has small, measurable effects on your body that matter in specific situations.
How Temperature Affects Hydration
The most important thing about water is that you actually drink enough of it, and temperature plays a surprisingly big role in how much you voluntarily consume. A study on dehydrated athletes found that water at 16°C (about 61°F, which is cool but not ice cold) led to the highest voluntary intake and the best overall hydration. People simply drank more of it than they did ice water or warm water.
Once water reaches your stomach, temperature differences largely disappear. Your stomach rapidly adjusts any liquid to match your internal body temperature before passing it into the small intestine, where absorption actually happens. So whether you drink ice water or room temperature water, by the time your body absorbs it, the temperature is essentially the same. The net hydration effect is identical.
Cold Water Slows Digestion Slightly
Cold water does leave the stomach more slowly than water closer to body temperature. Research published in the journal Gut found that the initial gastric emptying rate of a cold drink was significantly slower than a control drink at body temperature, and that the delay correlated directly with how much the cold liquid lowered the temperature inside the stomach.
For most people, this difference is trivial and corrects itself within minutes as the stomach warms the liquid. But if you have a sensitive digestive system or conditions like achalasia (a disorder where the esophagus has trouble moving food downward), cold water can be more problematic. A high-resolution manometry study found that cold water reduced the strength of esophageal contractions in healthy people by about a third compared to room temperature water. In people with swallowing difficulties, the reduction was similar. For anyone prone to cramping or discomfort after eating, room temperature water during meals is the gentler choice.
Cold Water During Exercise
This is where cold water has its clearest advantage. Drinking cold water or ice slurry during exercise in the heat appears to improve endurance performance by providing internal cooling. The body absorbs heat from the environment during prolonged exercise, and a cold drink acts as an internal heat sink, helping to keep your core temperature from rising as quickly.
The cooling benefit is real but more nuanced than it first appears. Research from a 2018 review found that the internal heat absorbed by warming up cold water is roughly offset by a temporary reduction in sweating. Your body senses the cold fluid arriving and briefly dials back sweat production, which reduces evaporative cooling from the skin. The net effect on core temperature during sustained exercise tends to be a wash. Still, the subjective sense of feeling cooler can itself improve performance, because perceived overheating is one of the things that makes you slow down or stop.
The Calorie-Burning Claim Is Real but Tiny
You may have heard that drinking cold water burns extra calories because your body has to warm it up. This is technically true. Your body expends energy heating ice water to 98.6°F. The actual number, according to UAMS Health, is about eight calories per glass. That’s roughly the caloric equivalent of a single almond. You would need to drink an impractical amount of ice water to make any meaningful dent in your daily calorie burn, so this is not a useful weight loss strategy by any measure.
Cold Water and Congestion
If you’re dealing with a stuffy nose or a cold, room temperature or warm water is the better choice. A study measuring nasal mucus velocity (how quickly mucus moves through your nasal passages, which reflects how well your nose clears itself) found that drinking cold water by sip significantly slowed mucus movement, dropping it from 7.3 to 4.5 millimeters per minute. Hot water by sip did the opposite, increasing mucus velocity from 6.2 to 8.4 millimeters per minute. The cold water effect persisted for at least 30 minutes, while the hot water benefit faded back to baseline in that same window.
This is why warm tea, broth, and soup feel so soothing when you’re congested. They’re not just comforting; they’re measurably helping your nasal passages clear faster.
Cold Water and Headaches
Cold-stimulus headaches (the “brain freeze” family of pain) are a real consideration for some people, particularly those who already get migraines. Research on cold-stimulus headaches found that between 55% and 74% of people with a history of migraines experienced headaches triggered by cold stimuli like ice water, compared to 23% to 46% of people with tension-type headaches. If you’re prone to migraines, drinking very cold water quickly can be an unwelcome trigger. Sipping slowly or choosing a less extreme temperature helps avoid this.
Which to Choose in Practice
The practical answer depends on what you’re doing. Cool water (not ice cold, closer to 60°F) is ideal for general daily hydration because people tend to drink more of it. During exercise in heat, cold water provides a welcome cooling sensation and may help you push a little longer. When you’re sick or congested, warm or room temperature water helps your nasal passages work better. If you have a sensitive stomach or esophageal issues, room temperature is gentler on digestion. And if you get migraines, cold water is worth avoiding or at least sipping slowly.
The differences between cold and room temperature water are modest in healthy people under normal conditions. The temperature that makes you reach for your water bottle more often is, for most purposes, the right one.