Drinking enough water every day is important for overall health. The amount of water a person needs varies based on factors like age, gender, activity level and climate. There are general recommendations for total daily water intake that can be used as a starting point.
Quick Answers
The average recommended daily water intake is around 2 liters or 67 ounces for women and 3 liters or 101 ounces for men. This equals roughly 8 glasses of 8 ounces each for women and 12 glasses for men.
Factors like exercise, hot weather and health conditions can increase water needs. Thirst is also an indicator that more water is needed.
Plain water is best for meeting daily needs, but other beverages like milk and juice can contribute to total fluid intake.
Urine color is a simple way to gauge hydration status. Pale yellow urine generally indicates adequate hydration, while dark yellow urine suggests dehydration.
Headache, fatigue, dizziness and constipation are common signs of mild dehydration. More severe dehydration requires medical treatment.
Recommended Daily Intake
The Institute of Medicine (IOM) has set general recommendations for total daily fluid intake based on U.S. survey data. These recommendations are:
- Women: Around 2.7 liters or 91 ounces per day
- Men: Around 3.7 liters or 125 ounces per day
This equates to roughly:
- Women: 8 glasses of 8 ounces each
- Men: 12 glasses of 8 ounces each
However, around 80% of total fluid intake is recommended to come from beverages, while the other 20% is recommended to come from food. So the IOM also sets these specific recommendations for total beverage intake:
- Women: Around 2.2 liters or 74 ounces per day
- Men: Around 3 liters or 101 ounces per day
This can be rounded to:
- Women: Around 2 liters or 67 ounces per day
- Men: Around 3 liters or 101 ounces per day
Plain water is the best source of hydration, but other beverages like milk, juice and herbal tea can contribute to total fluid needs. The recommendations are focused on preventing dehydration as well as possible health effects linked to very high or low fluid intakes.
Increasing Water Needs
Water needs can vary significantly based on factors like:
- Age
- Gender
- Activity level
- Climate and season
- Overall health
- Pregnancy or breastfeeding status
Exercise: Fluid needs increase dramatically with exercise due to fluid loss through sweat. Heavy sweating can easily double or triple water requirements.
Hot weather: Heat exposure through weather or saunas causes sweating and increases fluid needs. Thirst also increases in hot weather as the body’s way of signaling more water is needed.
High altitude: The air is drier at higher altitudes, which leads to more fluid loss. This causes increased thirst and water needs.
Illnesses: Vomiting, diarrhea and fever all lead to extra fluid loss and dehydration risk. Increased fluid intake is necessary during illness.
Pregnancy: Fluid demands increase during pregnancy to support fetal development and maternal health. Pregnant women require 10-13 cups (80-105 ounces) of total fluids per day.
Breastfeeding: Producing milk requires extra fluid. Breastfeeding women need about 13 cups (105 ounces) of total fluids per day.
Signs of Dehydration
Thirst is one of the first signs of dehydration. Additional symptoms can include:
- Fatigue
- Dizziness
- Irritability
- Headache
- Constipation
- Dark yellow or amber-colored urine
- Minimal urine output
- Rapid heart rate
- Low blood pressure
Severe dehydration is a medical emergency requiring hospitalization for intravenous fluids. Symptoms can include:
- Extreme thirst
- Fever
- Confusion
- Unconsciousness
- Shriveled skin
- Lack of sweating
- Little or no urination
Assessing Hydration Status
Here are simple ways to estimate your hydration status:
- Thirst – Feeling thirsty is one of the first signs that the body needs more fluid.
- Urine color – Pale yellow urine generally indicates you are well hydrated. Dark yellow or amber urine suggests dehydration.
- Urine volume – Consistently producing a normal amount of pale urine is a good indicator of adequate hydration.
Several lab tests can also help assess hydration status, including:
- Urine specific gravity
- Urine osmolality
- Blood tests for electrolytes like sodium and potassium
- Blood urea nitrogen (BUN) to creatinine ratio
Groups at Higher Risk of Dehydration
Some people and groups are at increased risk of dehydration, including:
- Infants and children
- Older adults
- People living in hot climates
- Athletes and heavy exercisers
- People at high altitudes
- People with fevers, vomiting or diarrhea
- People taking medications that increase fluid loss
- People who have trouble swallowing or accessing fluids
Paying attention to signs of dehydration and intentionally increasing fluid intake can help reduce dehydration risk in these populations.
Tips for Meeting Daily Fluid Intake Recommendations
Here are some simple tips for getting enough fluids each day:
- Drink a full glass of water first thing in the morning and with every meal
- Carry a water bottle with you throughout the day for easy sipping
- Choose water over sugary drinks like soda, fruit juice and sports drinks
- Eat fruits and vegetables with high water content like cucumbers, berries and melons
- Add slices of lemon, lime or cucumber to water for flavor
- Set a daily alarm or app reminder to drink water at regular intervals
- Drink before, during and after exercise
- Drink when you are feeling thirsty or dizzy
- Avoid alcoholic beverages which can act as diuretics
Health Benefits of Proper Hydration
Meeting daily water intake recommendations has many benefits for health:
- Brain function – Even mild dehydration can impair concentration, memory, mood and brain performance.
- Headaches – Dehydration is a common headache trigger. Drinking water can often relieve headaches.
- Constipation – Staying hydrated helps prevent constipation by softening stool and aiding digestion.
- Kidney function – Adequate water intake helps flush toxins and reduce kidney stone risk.
- Heart health – Dehydration stresses the cardiovascular system. Drinking water supports heart function.
- Athletic performance – Dehydration harms endurance, strength and recovery. Proper hydration enhances performance.
- Weight management – Water is a zero-calorie beverage that helps reduce overall calorie intake when substituted for sugary drinks.
Drinking enough water each day provides wide-ranging benefits for mental and physical health, appearance and performance.
Too Much Water Intake
While dehydration poses health risks, consuming extremely high amounts of water can also be dangerous:
- Overhydration – Excessive water intake that drastically dilutes sodium levels in the blood is called overhydration. This is rare but can be fatal.
- Water intoxication – Consuming over 3-4 liters of water quickly can dangerously alter electrolyte balance, leading to swelling in the brain and other tissues.
For most healthy people, the kidneys are excellent at removing excess water. Intakes under one gallon (3.8 liters) per day are unlikely to pose harm.
However, endurance athletes who drink high volumes to replace sweat losses may need to moderate intake to avoid dangerously low sodium levels.
Meeting Needs Through Food
While fluids in beverages meet most hydration needs, eating fresh fruits and vegetables with high water content also contributes:
| Food | Water Content % |
|---|---|
| Cucumber | 95% |
| Strawberries | 92% |
| Watermelon | 92% |
| Grapefruit | 91% |
| Peaches | 89% |
| Pineapple | 87% |
| Oranges | 87% |
| Skim milk | 91% |
| Yogurt | 85% |
| Cooked rice | 70% |
Incorporating these foods into meals and snacks provides valuable dietary water to help meet hydration needs.
Hydration Tips for Special Populations
Certain groups have unique hydration considerations:
Infants
- 0-6 months: Breastfed and formula-fed infants get hydration from milk.
- 6-12 months: Can drink some water in addition to breastmilk or formula. Limit water to 2-4 ounces per day.
Young Children
- 1-3 years old: May need 4-6 cups of fluids per day including milk and water.
- 4-8 years old: May need 4-8 cups of fluids per day.
Since milk is a major source of hydration for kids, limit juice and sugary drinks.
Older Adults
- May lose ability to conserve water with age, making them prone to dehydration.
- Thirst perception declines so they may need to drink on a schedule rather than relying on thirst.
- Certain medications can increase urination and fluid needs.
Endurance Athletes
- Sweat losses before, during and after exercise increase fluid requirements.
- Drink 16-24 ounces of water or sports drink every 30-60 minutes during exercise.
- Weighing before and after exercise monitors sweat losses and hydration status.
Common Hydration Questions
Does caffeine dehydrate you?
Caffeine is a mild diuretic, meaning it increases urine output. However, regular coffee and tea consumers develop a tolerance to this effect. Moderate caffeine intake of 400 mg per day (4 cups coffee) is not dehydrating for most people.
Are sports drinks more hydrating than water?
For most activities, plain water is best for hydration. Sports drinks provide an advantage when exercising intensely for over an hour by replacing sweat losses of electrolytes and providing fuel.
Do you need to drink 8 glasses of water per day?
While often stated as a general rule, the origins of “8 glasses a day” are unclear. The adequate amount varies based on factors like gender, activity level and health status. Using thirst and urine color as guides is more accurate than sticking to a rigid number.
Is it possible to drink too much water?
Yes, consuming excessively high amounts of plain water can dangerously dilute blood sodium levels, especially if matching losses through heavy sweating. Moderately high intakes below one gallon daily are unlikely to pose harm for healthy people.
The Bottom Line
Daily water needs range from 2-3 liters per day for most adults from all sources. Plain water is best, but fluids from foods and other beverages contribute to total needs.
Listen to your body’s thirst signals and aim for pale yellow urine. Drink extra when you are physically active or exposed to heat.
Getting enough fluids supports energy, heart health, weight management and overall well-being.
