EFSA considers about 2.0 litres of water a day adequate for women and 2.5 litres for men, and roughly 20% of that usually comes from food. That means around 8 glasses of drinks for women and 10 for men. A 2022 Science study of 5,604 people found needs vary widely and that '8 glasses for everyone' lacks objective evidence.
Key takeaways
- EFSA: about 2.0 L of water a day for women and 2.5 L for men, including water from food.
- Roughly 80% usually comes from drinks: about 8 glasses for women, 10 for men.
- A 2022 study of 5,604 people found water needs vary with body size, activity and climate.
- Tea, coffee, milk and water-rich foods all count; sugary drinks add calories too.
- Pale yellow urine and thirst are practical everyday guides.
How much water do adults need per day?
The European Food Safety Authority (EFSA) considers a daily intake of about 2.0 litres adequate for women and 2.5 litres for men. Türkiye's national nutrition guide (TÜBER) uses the same figures for total fluid and explains how they are usually met: about 80% from water and other drinks and about 20% from food. Pregnant women need roughly 300 ml more a day and breastfeeding women about 700 ml more, according to TÜBER.
| Women | Men | |
|---|---|---|
| Total water (drinks + food) | 2.0 L | 2.5 L |
| From drinks (≈ 80%) | 1.6 L | 2.0 L |
| In 200 ml glasses | ≈ 8 glasses | ≈ 10 glasses |
| From food (≈ 20%) | 0.4 L | 0.5 L |
The UK's NHS gives a simpler rule of thumb: about 6 to 8 cups or glasses of fluid a day, and more if you are pregnant or breastfeeding, in a hot environment, active for long periods, or ill or recovering. So the usual range for adults lands somewhere between 1.5 and 2 litres of drinks a day, with food covering the rest.
Is "8 glasses a day" actually based on science?
Not as a universal rule. In 2022 a large study in Science measured daily water turnover, the amount of water moving through the body each day, in 5,604 people aged 8 days to 96 years from 23 countries, using isotope tracking rather than questionnaires. Turnover depended on body size, body composition, physical activity, athletic status, pregnancy, age, climate, altitude and humidity. On average it was higher in men (4.3 L a day) than women (3.4 L a day) and declined in later life.
The authors concluded that one size does not fit all and that the common advice to drink eight 8-ounce glasses (about 2 litres) a day is not backed by objective evidence. Note that turnover is not the same as what you need to drink: it also includes water from food and water your body makes when it burns energy. For most healthy adults, the guideline ranges above plus thirst are a reasonable guide.
What counts toward your daily water?
More than plain water does. According to the NHS, water, lower-fat milk and drinks with little or no sugar, including tea and coffee, all count. Food matters too. These USDA values show how much water common foods contain:
| Food | Water content |
|---|---|
| Cucumber | 96.7% |
| Tomato | 94.5% |
| Watermelon | 91.4% |
| Plain whole-milk yogurt | 87.9% |
| Apple with skin | 85.6% |
| Cooked lentils | 69.6% |
Soups, salads, yogurt dishes and fruit all help. Turkish lentil soup, cacık, Spanish gazpacho and a big mixed salad are good examples. In Sporty's per-serving estimates, cacık is about 120 kcal and gazpacho about 170 kcal; real values depend on recipe and portion.
Do drinks with calories count?
They count as fluid, but they also count as food. A 355 ml can of regular cola has about 155 kcal and 37 g of sugar according to USDA data, while water has none. The NHS suggests limiting fruit juice and smoothies to one small 150 ml glass a day, with a meal. For more on sweet drinks, see sugar limits and hidden sources and liquid calories.
Does drinking water help with weight loss?
Water has no calories, so swapping sugary drinks for water is one of the simplest ways to lower your intake. Beyond that, the evidence is modest. In a small randomised trial published in 2010, 48 adults aged 55 to 75 followed a reduced-calorie diet, and half also drank 500 ml of water before each main meal. Over 12 weeks the water group lost about 2 kg more, partly because they ate less at meals. The study was small, older adults only, and the difference in percentage of weight lost was not statistically significant, so treat it as a helpful habit rather than a weight-loss method.
Water also explains many confusing scale jumps. A salty meal, more carbohydrate or a hard workout can make you hold extra water for a few days. Our guide to water weight vs fat loss explains how to read those changes.
How can you tell if you are drinking enough?
- Urine colour. The NHS suggests aiming for a clear, pale yellow colour. Dark yellow usually means you need more fluid.
- Thirst. For most healthy adults, drinking when thirsty and with meals works well.
- Context. Heat, long or intense exercise, illness with fever, vomiting or diarrhoea, pregnancy and breastfeeding all raise needs.
Older adults may feel less thirsty and benefit from drinking at regular times. If a doctor has told you to limit fluids, for example because of some heart or kidney conditions, follow that advice instead of general guidelines.
What happens when you lose too much water?
TÜBER summarises how symptoms build as the body loses water, measured as a share of body water:
| Body water lost | Typical effect |
|---|---|
| 0–1% | Thirst |
| 2% | Strong thirst, restlessness, loss of appetite |
| 3% | Lower blood volume, poorer physical performance |
| 4% | Physical work feels harder, nausea |
| 5% | Difficulty concentrating |
The practical message is simple: thirst is an early signal, so respond to it, especially on hot days and during exercise.
What does a practical day look like?
For a woman aiming at about 1.6 litres from drinks:
- A glass of water after waking: 200 ml.
- Two cups of tea or coffee at breakfast: 400 ml.
- A glass of water with lunch and one in the afternoon: 400 ml.
- A glass of ayran or milk with dinner: 200 ml.
- Two glasses of water during the evening: 400 ml.
That is 1.6 litres from drinks, before counting soup, fruit and vegetables. A man can add two more glasses, and anyone who trains or spends time in the heat should drink more around that activity. Keeping a bottle in sight is often more useful than any app reminder, although Sporty can show steps and water alongside your meals as useful context.
Do not worry about hitting an exact number every day. Needs change with the weather, your activity and what you eat, so a range and your own body signals are better guides than a strict target.
Frequently asked questions
How many litres of water should I drink a day?
EFSA considers about 2.0 L a day adequate for women and 2.5 L for men in total, with about 20% usually coming from food. That leaves roughly 1.6 L and 2.0 L from drinks.
Do tea and coffee count toward water intake?
Yes. The NHS says water, lower-fat milk and low-sugar drinks, including tea and coffee, all count toward your fluid intake.
Is 8 glasses a day a myth?
It is a reasonable rough average for many adults, but not a universal rule. A 2022 Science study found water turnover varies widely and that the 8-glass advice is not backed by objective evidence.
Does drinking water before meals help weight loss?
A small 2010 trial found people on a reduced-calorie diet who drank 500 ml before meals lost about 2 kg more over 12 weeks, but the evidence is limited. Replacing sugary drinks with water is the clearer benefit.
Who needs more water?
People who are pregnant or breastfeeding, very active, in hot weather or ill with fever, vomiting or diarrhoea. If a doctor has told you to limit fluids, follow that advice.
Sources
- EFSA (2010), European dietary reference values for nutrient intakes (water)
- T.C. Sağlık Bakanlığı, Türkiye Beslenme Rehberi (TÜBER) 2022
- Yamada et al. 2022, Variation in human water turnover (Science)
- NHS, Water, drinks and your health
- Dennis et al. 2010, Water consumption increases weight loss during a hypocaloric diet (Obesity)
- USDA FoodData Central
This article is general information, not medical advice. If you have a health condition, are pregnant or under 18, talk to a doctor or registered dietitian before changing your diet.