Water
Also known as Total water, Fluids, Hydration
Water makes up about 60 percent of body weight and is essential for temperature regulation, nutrient transport, joint lubrication, and waste removal. The Adequate Intake for total water is about 3.7 liters/day for men and 2.7 liters/day for women, counting water from all beverages and foods. Roughly 80 percent of intake comes from drinks and 20 percent from food.
Why it matters
What it does in your body
- Regulates body temperature through sweat
- Transports nutrients and oxygen to cells
- Removes waste through urine and stool
- Lubricates joints and cushions tissues
- Maintains blood volume and pressure
By age, sex, and life stage
How much you need
The Adequate Intake for total water is about 3.7 liters/day (roughly 125 oz) for adult men and 2.7 liters/day (roughly 91 oz) for adult women. This total includes water from all beverages and from food; about 80 percent typically comes from drinks and 20 percent from food. Individual needs vary widely, and thirst is a useful guide for most healthy people.
Recommended intake across life
in liters/dayBars scale to the highest recommendation shown. Where men and women differ, both values are listed.
Full reference table
| Life stage | Male | Female |
|---|---|---|
| Adult men 19+ | 3.7 L total water (AI) | n/a |
| Adult women 19+ | n/a | 2.7 L total water (AI) |
| Pregnancy | n/a | 3.0 L total water (AI) |
| Lactation | n/a | 3.8 L total water (AI) |
Values in liters/day. AI marks an Adequate Intake, used when there is not enough evidence for a formal recommendation.
What moves the number
What changes your needs
Activity and heat
Exercise, hot weather, and heavy sweating raise fluid needs substantially.
Body size
Larger bodies and higher calorie needs require more total water.
Pregnancy and lactation
Needs rise to about 3.0 L/day in pregnancy and 3.8 L/day during lactation.
Illness
Fever, vomiting, and diarrhea increase losses and the need to replace fluids.
Running low
Signs you might not get enough
Most at risk: Older adults with a blunted thirst response, athletes, outdoor workers, and anyone with vomiting, diarrhea, or fever are at higher risk.
Too much
Can you get too much?
Overhydration is rare but serious. It occurs mainly in endurance athletes who drink excessively; spacing fluids and using electrolytes during long efforts helps prevent it.
Where to get it
Best food sources
The bottom line
Aim for roughly 2.7 to 3.7 liters of total water a day from drinks and food, more when hot or active, and use thirst and pale urine as everyday guides.
Track water automatically
Water is one of the 92 nutrients Vora reads from a photo of your meal, so you can see where you stand without weighing or logging by hand.
Sources and method
The recommended intakes, upper limits, and food-source amounts on this page come from the primary references below. Numbers were checked against the current NIH Office of Dietary Supplements fact sheets and the Institute of Medicine (now the National Academies) Dietary Reference Intakes.
- Institute of Medicine, Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate (2005)
- National Academies of Sciences, Engineering, and Medicine
This page is for general education, not medical advice. Reference intakes are population averages for healthy people and do not replace guidance from your doctor or a registered dietitian, especially if you are pregnant, managing a health condition, or considering supplements.