How much water should I drink a day?
There is no single amount of water that is right for everyone. What exists are population reference values — numbers that describe what is usually enough for healthy adults in mild conditions — and they are easy to misread.
Total water is not the same as plain water
The best-known references count total water: plain drinking water, every other drink, and the water in food.
- The European Food Safety Authority (EFSA) sets adequate intakes of total water of 2.0 litres a day for women and 2.5 litres for men, for moderate temperatures and moderate activity. Roughly 20–30% of that usually comes from food.
- The US National Academies set adequate intakes of total water of about 2.7 litres a day for women and 3.7 litres for men, again including food, and state that these are not a specific requirement for each person.
- The NHS (UK) suggests aiming for 6 to 8 cups or glasses of fluid a day, and notes that water, lower-fat milk and lower-sugar drinks, including tea and coffee, all count.
So “2 litres” is not a rule for plain water. Part of the reference is met by food and other drinks.
Why the numbers differ
The references differ because they come from different surveys and different definitions. Each describes what healthy people in that population typically take in, not a minimum anybody must reach.
Your own needs can be higher or lower. Official sources name heat, long physical activity, illness, pregnancy and breastfeeding as reasons you may need more. Some medical conditions mean a doctor sets a limit on fluids instead. If that applies to you, their advice comes first.
A simple check the NHS mentions
The NHS suggests drinking enough during the day that your pee is a clear, pale yellow colour. That check follows your day, the weather and your activity in a way a fixed number cannot.
Where Water Tracker fits
Water Tracker does not calculate how much water you need. You choose your own daily goal — or no goal at all — and the app only counts what you log against it. If you want a number, the references above are a starting point to discuss with a health professional, not a target the app sets for you.
Sources
- EFSA Panel on Dietetic Products, Nutrition and Allergies (2010). Scientific Opinion on Dietary Reference Values for water. EFSA Journal 8(3):1459.
- National Academies (2004). Report sets dietary intake levels for water, salt, and potassium.
- NHS. Water, drinks and your health.
General information with sources, not medical advice.