The general guideline for daily water intake is 3,700 ml for adult men and 2,700 ml for adult women. Those numbers, set by the U.S. National Academies, cover total water from all sources, including food. Since food typically supplies about 20% of your daily water, the amount you actually need to drink comes out to roughly 2,960 ml for men and 2,160 ml for women.
What “Total Water” Actually Means
The 3,700 ml and 2,700 ml figures aren’t just glasses of water. They include every drop of fluid you take in: plain water, coffee, tea, juice, milk, soup, and the moisture locked inside solid food. A cucumber is over 95% water. A chicken breast is about 65%. All of it counts toward your daily total.
That 20% food contribution is an average based on a typical mixed diet. If you eat a lot of fruits, vegetables, and soups, food may cover closer to 30%. If your diet leans toward dry, processed foods, it may be closer to 15%. Either way, the practical target for drinking fluids lands in this range:
- Men: about 2,600 to 3,000 ml of fluids per day
- Women: about 1,900 to 2,200 ml of fluids per day
These recommendations stay the same from age 19 through 70 and beyond. The National Academies did not find sufficient evidence to adjust the target for older adults, though older adults are more prone to dehydration because thirst signals weaken with age.
Where the “8 Glasses a Day” Rule Fits
You’ve probably heard you should drink eight glasses of water a day. At about 240 ml per glass, that works out to roughly 1,920 ml. It’s a reasonable ballpark for women’s drinking needs and a useful minimum for men, but it’s not based on any single study. Think of it as a simple, memorable starting point rather than a precise prescription. Most people who drink when they’re thirsty and have water with meals end up in the right range without tracking milliliters.
Pregnancy and Breastfeeding
Pregnant women need an additional 300 ml per day on top of the standard recommendation. During breastfeeding, that extra need jumps to 600 to 700 ml per day, since breast milk is roughly 87% water. For a breastfeeding woman, total fluid intake from drinks alone should be somewhere around 2,700 to 2,900 ml daily.
How Exercise Changes Your Needs
Sweat rates during exercise range from 500 ml to 4,000 ml per hour depending on intensity, fitness level, body size, and heat. A brisk walk on a cool day sits at the low end. A hard run in summer heat can push toward the high end. The general guideline for staying hydrated during activity is to drink about 200 ml every 15 to 20 minutes, which works out to 600 to 800 ml per hour.
That’s on top of your baseline daily intake. If you exercise for an hour and sweat moderately, adding 500 to 1,000 ml to your usual daily total is a reasonable adjustment. For longer or more intense sessions, weighing yourself before and after exercise gives a more precise picture: every kilogram lost represents roughly 1,000 ml of fluid you need to replace.
How to Tell If You’re Drinking Enough
Counting milliliters works, but your body gives you simpler signals. Urine color is the most reliable everyday indicator. Pale, straw-colored urine means you’re well hydrated. Medium yellow suggests you need more fluid. Dark yellow or amber, especially in small amounts with a strong smell, points to dehydration.
A few things can throw off the color test. B vitamins turn urine bright yellow regardless of hydration. Beets can make it pink. Certain medications change the color too. If you’re taking any of these, thirst and urine volume are better guides than color alone. Urinating roughly every two to four hours during the day, with a decent volume each time, generally signals adequate hydration.
Can You Drink Too Much?
Yes. Drinking large volumes in a short window can dilute the sodium in your blood to dangerous levels, a condition called hyponatremia. Symptoms include nausea, headache, confusion, and in severe cases, seizures. This is rare in everyday life but does occur in endurance athletes and people who force themselves to drink far beyond thirst.
Your kidneys can process a limited amount of water per hour. Drinking more than about 1,000 ml (one liter) per hour is likely too much for most people. In some cases, consuming 3,000 to 4,000 ml over just one to two hours has triggered water intoxication. The simple rule: spread your intake throughout the day rather than gulping large amounts at once.
Quick Reference by Group
- Adult men: 3,700 ml total water per day (about 3,000 ml from drinks)
- Adult women: 2,700 ml total water per day (about 2,200 ml from drinks)
- Pregnant women: add 300 ml to the standard recommendation
- Breastfeeding women: add 600 to 700 ml to the standard recommendation
- During exercise: roughly 200 ml every 15 to 20 minutes on top of baseline
- Upper limit per hour: stay under 1,000 ml to avoid overhydration