How Much Water Should I Drink Per Day?
One of the most common health questions is: "How much water should I drink each day?" The answer depends on several factors including your body weight, age, gender, activity level, and the climate you live in. This guide breaks down the science behind daily water intake recommendations.
The often quoted 8 glasses a day rule is a simplification. In reality, the National Academies of Sciences, Engineering, and Medicine recommends about 3.7 liters of total daily water intake for men and 2.7 liters for women, including water from beverages and food.
Recommended Daily Intake by Age & Gender
| Group | Daily Intake | Notes |
|---|---|---|
| Children (4-8 years) | 1.200 - 1.600 | Includes water from food and beverages |
| Children (9-13 years) | 1.600 - 2.100 | Boys need more than girls |
| Teens (14-18 years) | 1.800 - 2.600 | Higher for active teens |
| Adult Women (19+) | 2.000 - 2.700 | About 2.7 L total including food |
| Adult Men (19+) | 2.500 - 3.700 | About 3.7 L total including food |
| Pregnant Women | 2.300 - 2.700 | Increased blood volume requires more fluid |
| Breastfeeding Women | 2.600 - 3.400 | Milk production requires significant water |
| Older Adults (65+) | 1.700 - 2.500 | Thirst sensation decreases with age |
Weight-Based Calculation
The most personalized approach uses your body weight. The widely accepted formula is . For example, a 70 kg person needs approximately 2,100-2,450 ml of water per day as a baseline.
Use our water intake calculator to get a personalized recommendation that factors in your weight, activity level, and climate, or check our weight-based reference table.
Factors That Increase Your Needs
Exercise increases water loss through sweat. Active individuals need 500-1,000+ ml more per day depending on intensity and duration.
Heat and humidity increase perspiration significantly. In tropical climates, needs can increase by 500-1,500 ml.
Above 2,500 m, increased respiration and urination require 500-1,000 ml extra per day.
Fever, vomiting, and diarrhea cause rapid fluid loss. Oral rehydration solutions may be needed.
Pregnant women need about 300 ml more, and breastfeeding mothers need 700+ ml extra daily.
Risks of Overhydration
While dehydration is the more common concern, overhydration is a real risk, particularly for endurance athletes. Drinking excessive water dilutes blood sodium levels, which can cause nausea, headache, confusion, seizures, and in extreme cases, death.
The key is to drink to thirst, spread intake throughout the day, and increase consumption gradually during exercise. If your urine is consistently clear and copious, you may be overhydrating.