Neither cold nor warm water is universally better. The best temperature depends on what you’re doing: exercising, eating, fighting a cold, or simply trying to stay hydrated throughout the day. Each temperature has real, measurable effects on your body, and the practical differences matter more in some situations than others.
Cool Water Wins for Staying Hydrated
The single most important thing about water is that you actually drink enough of it. And temperature has a surprisingly strong effect on how much you’ll voluntarily consume. In a study of dehydrated athletes, water served at 16°C (about 61°F, or cool but not cold) resulted in the highest voluntary intake compared to both colder and warmer options. The least amount consumed? Hot water at 58°C. People given the chance to mix their own preferred temperature consistently chose water around 15°C.
This lines up with recommendations from the American College of Sports Medicine, which suggests fluids between 15°C and 22°C (roughly 59°F to 72°F) for optimal hydration. Sports Medicine Australia’s 2025 guidelines similarly recommend cold fluids before exercise in hot conditions as a cooling strategy. The takeaway: if your goal is simply to drink more water, keeping it cool gives you the best chance of doing that naturally.
Cold Water During Exercise
Cold water offers a real advantage when you’re working out, particularly in warm environments. During a 60-minute exercise session, people drinking cold water saw their core temperature rise by only 0.83°C, compared to 1.13°C for those drinking room-temperature water. More notably, the cold water group delayed any significant increase in body temperature for about 45 minutes, while the room-temperature group saw a rise after just 15 minutes.
That said, the performance differences were modest. Endurance, jump distance, and total repetitions were nearly identical between the two groups. Bench press performance actually dipped slightly with cold water. So cold water during exercise is primarily a thermoregulation tool. It helps your body manage heat, which can make a hard workout feel more tolerable, even if it doesn’t dramatically change your output.
The Calorie-Burning Myth
You may have heard that drinking ice water forces your body to burn extra calories warming it up. This is technically true and practically meaningless. Your body expends about eight calories bringing a glass of ice water up to body temperature. That’s the caloric equivalent of a small pickle. Drinking eight glasses of ice water a day would burn roughly 64 extra calories, less than a single apple. Cold water is not a weight-loss strategy.
One animal study did find that rats drinking cold water gained more lean mass and less fat than those drinking room-temperature water, likely due to slightly increased energy expenditure over time. But this hasn’t been replicated in humans in any meaningful way, and it certainly doesn’t support the popular myth that cold water “solidifies fat” in your stomach. Your stomach rapidly warms everything you consume to body temperature. Fats are broken down by digestive enzymes regardless of the temperature of the water you drank alongside them.
Warm Water for Congestion and Sinus Relief
Warm water has one clear, well-documented advantage: it helps clear your nasal passages when you’re sick. Sipping hot water increased nasal mucus velocity from 6.2 to 8.4 millimeters per minute, a roughly 35% improvement that helps your body move mucus out more efficiently. The effect comes partly from inhaling the steam as you sip, which is why drinking hot liquid through a straw (which bypasses the nose) was less effective.
Cold water did the opposite. Five minutes after drinking cold water, nasal mucus velocity dropped from 7.3 to 4.5 millimeters per minute, making congestion worse. The warm water benefits faded after about 30 minutes, but during a cold or sinus infection, that repeated short-term relief adds up. If you’re stuffed up, hot water or hot soup sipped from a cup is the clear winner.
Warm Water and Digestion
Many people swear that warm water in the morning helps with digestion, and there’s a plausible reason for that. Your entire gastrointestinal tract is a muscular tube, and warmth may help relax it, easing constipation and promoting movement. Cleveland Clinic notes that while scientific research specifically comparing hot water to cold water for digestion is thin, the mechanism makes physiological sense. Heat applied to muscle tissue promotes relaxation, which is why heating pads work for cramps.
Cold water, meanwhile, empties from the stomach more slowly than body-temperature water. A study of healthy volunteers found that drinks served at 4°C had a significantly slower initial gastric emptying rate compared to drinks at 37°C (body temperature). If you feel bloated or uncomfortable after drinking ice water with meals, this slower emptying could be part of the reason. Warm or room-temperature water during meals is a reasonable choice if you’re prone to digestive discomfort.
When Temperature Matters for Medical Reasons
For most people, water temperature is a matter of preference. But for those with achalasia, a condition where the esophagus has trouble moving food into the stomach, temperature makes a significant clinical difference. Cold water increases pressure at the lower esophageal sphincter and worsens swallowing difficulty, regurgitation, and chest pain. Hot water does the opposite: it reduces that pressure, helps the sphincter relax, and relieves symptoms. In one group of 34 achalasia patients, hot water relieved chest pain in 84% of cases and reduced regurgitation in 79%.
Heat therapy also has documented benefits for menstrual cramps. While this research focuses on external heat (heating pads, warm compresses), the underlying principle is the same: warmth relaxes smooth muscle, increases blood flow to the pelvic area, and reduces pain from muscle spasms. Drinking warm water won’t replace a heating pad, but it fits within the same general approach of using warmth to manage cramping.
Picking the Right Temperature
The best approach is to match the temperature to the moment:
- During and before exercise: Cold water helps manage your core temperature, especially in heat. Pre-cooling with cold water or an ice slushy before a workout is a well-supported strategy.
- For everyday hydration: Cool water around 15°C to 16°C (about 60°F) encourages you to drink the most, which matters more than any other factor.
- When you’re congested: Hot water sipped from a cup clears nasal passages and improves mucus flow. Cold water makes congestion worse.
- With meals or for digestion: Warm or room-temperature water empties from the stomach faster and may ease digestive discomfort.
- For cramps or muscle tension: Warm water complements the general principle that heat relaxes smooth muscle tissue.
If none of these situations apply and you’re just thirsty, drink whatever temperature you find most appealing. The water you’ll actually finish is always better than the “optimal” water sitting untouched on your desk.