How Many Glasses of Water a Day? Staying Hydrated Explained

Water is vital for maintaining good health. Are you drinking enough? These guidelines will help you determine your ideal daily water intake. By Mayo Clinic Staff

Determining exactly How Many Glasses Of Water A Day you should drink isn’t a straightforward calculation. While it’s a common question, there’s no universal answer that applies to everyone. Recommendations have varied across studies for years because your individual hydration needs are influenced by a multitude of factors. These include your overall health, your activity level, and the climate where you live.

While there’s no magic number, understanding your body’s fluid requirements is key to estimating how much water you personally need to drink each day to stay healthy and hydrated.

What Are the Health Benefits of Drinking Water?

Water is the primary chemical component of your body, making up a significant portion, approximately 50% to 70% of your body weight. This highlights just how crucial water is; your body simply cannot function without it.

Every cell, tissue, and organ in your body relies on water to work correctly. Water plays a vital role in numerous bodily functions, for example, it:

• Removes waste products through urination, perspiration, and bowel movements, effectively detoxifying your body.
• Regulates and maintains a normal body temperature, preventing overheating or excessive cooling.
• Acts as a lubricant and cushion for your joints, ensuring smooth movement and reducing friction.
• Protects sensitive tissues, including your spinal cord and organs, from damage.

A lack of sufficient water intake can quickly lead to dehydration. Dehydration is a condition that occurs when your body loses more fluids than you take in, disrupting normal bodily functions. Even mild dehydration can have noticeable effects, draining your energy levels and causing fatigue. Recognizing the importance of water and understanding how many glasses of water a day are appropriate for you is essential for maintaining optimal health.

How Much Water Do You Need Daily?

Every single day, you naturally lose water through various bodily processes, including breathing, sweating, urination, and bowel movements. To maintain proper bodily function, it’s crucial to replenish this lost water supply. This replenishment is achieved by consuming fluids and foods that contain water throughout the day.

So, how much fluid does a typical, healthy adult living in a moderate climate actually need? The U.S. National Academies of Sciences, Engineering, and Medicine have determined what constitutes an adequate daily fluid intake. Their general recommendations are:

• For men, approximately 15.5 cups (3.7 liters) of fluids per day.
• For women, approximately 11.5 cups (2.7 liters) of fluids per day.

It’s important to note that these recommendations encompass total fluid intake from all sources, including water, other beverages, and the moisture content in food. Interestingly, food typically contributes around 20% of our daily fluid intake, with the remaining 80% coming from drinks. Therefore, while aiming for a certain number of glasses of water a day is helpful, remember that your overall fluid intake is what truly matters for staying hydrated.

Debunking the 8 Glasses of Water a Day Advice

You’ve likely encountered the common health advice to drink eight glasses of water a day. This is a simple and memorable guideline, and it serves as a reasonable general goal for many people.

For most healthy individuals, staying adequately hydrated can be achieved by simply drinking water and other fluids whenever they feel thirsty. Listening to your body’s thirst cues is often sufficient. For some people, consuming fewer than eight glasses of water a day might be perfectly adequate. Conversely, others might require more than eight glasses to meet their individual needs.

Your total fluid intake may need to be adjusted based on several variable factors:

• Exercise: Any physical activity that causes you to sweat necessitates drinking extra water to compensate for fluid loss. It’s crucial to increase your water intake before, during, and after any workout or exercise session.
• Environment: Hot or humid weather conditions promote sweating, leading to increased fluid loss and thus requiring additional fluid intake. Dehydration can also be a concern at high altitudes due to increased respiration and lower humidity.
• Overall Health: When you experience conditions like fever, vomiting, or diarrhea, your body loses fluids at a higher rate. In these situations, it’s essential to drink more water or follow medical advice, which might include consuming oral rehydration solutions to restore lost electrolytes and fluids. Other health conditions, such as bladder infections and urinary tract stones, may also necessitate increased fluid intake.
• Pregnancy and Breastfeeding: If you are pregnant or breastfeeding, your body requires additional fluids to support both your own hydration and the needs of your baby. Increased fluid intake is crucial during these periods.

Are There Other Ways to Stay Hydrated Besides Water?

No, relying solely on plain water isn’t the only way to meet your daily fluid requirements. The food you eat contributes significantly to your overall hydration. Many fruits and vegetables have a high water content; for example, watermelon and spinach are composed of nearly 100% water by weight. Incorporating these water-rich foods into your diet can contribute to your daily fluid intake.

Furthermore, various beverages besides water can help you stay hydrated. Milk, 100% fruit juice, and herbal teas are primarily composed of water and can count towards your daily fluid goals. Even caffeinated beverages like coffee and soda, despite their diuretic effects, still contribute to your overall daily water intake. However, it’s advisable to consume sugary drinks in moderation. Regular sodas, energy drinks, sports drinks, and other sweetened beverages are often high in added sugars and can contribute unnecessary calories to your diet, potentially hindering your health goals. Opting for healthier choices for hydration is always recommended.

How to Tell If You Are Drinking Enough Water

A simple way to gauge whether you’re drinking enough fluids is to pay attention to your body’s signals. Generally, your fluid intake is likely adequate if:

• You rarely experience the sensation of thirst.
• Your urine appears colorless or light yellow. Darker urine is often an indicator of dehydration.

For personalized advice and to determine the precise amount of water that’s right for your individual needs, consulting your doctor or a registered dietitian is always a good step. They can assess your specific health status and lifestyle factors to provide tailored recommendations.

To actively prevent dehydration and ensure your body has the fluids it requires to function optimally, make water your primary beverage choice throughout the day. It’s a beneficial habit to drink a glass of water:

• With each meal and in between meals, spacing out your fluid intake throughout the day.
• Before, during, and after any physical activity or exercise.
• Whenever you feel thirsty, responding promptly to your body’s thirst cues.

Is It Possible to Drink Too Much Water?

While it’s important to stay hydrated, drinking excessive amounts of water is rarely a concern for healthy, well-nourished adults with normal kidney function. However, in specific situations, overhydration can become a problem. Athletes, for instance, might occasionally drink too much water in an attempt to prevent dehydration during prolonged or intense exercise.

When you consume an excessive amount of water, your kidneys may not be able to eliminate the excess fluid quickly enough. This can lead to a dilution of the sodium content in your blood, a condition known as hyponatremia. Hyponatremia can be serious and even life-threatening in severe cases, as sodium is crucial for various bodily functions, including nerve and muscle function. It’s important to maintain a balance and drink water in appropriate amounts, listening to your body’s needs rather than drastically overdoing it.

From Mayo Clinic to your inbox

Sign up for free and stay up to date on research advancements, health tips, current health topics, and expertise on managing health. Click here for an email preview.

Products and Services

See also

References

1. Office of Patient Education. The heat is on! Precautions for people with diabetes during the summer months. Mayo Clinic, 2018.
2. Auerbach PS, et al., eds. Dehydration and rehydration. In: Auerbach’s Wilderness Medicine. 7th ed. Elsevier; 2017. https://www.clinicalkey.com. Accessed Oct. 9, 2020.
3. Water & nutrition. U.S. Centers for Disease Control and Prevention. https://www.cdc.gov/healthywater/drinking/nutrition/index.html. Accessed Oct. 2, 2020.
4. Dietary reference intakes for electrolytes and water. U.S. National Academies of Science, Engineering, and Medicine. https://www.nationalacademies.org/our-work/dietary-reference-intakes-for-electrolytes-and-water. Accessed Oct. 2, 2020.
5. Franklin BA. Exercise prescription and guidance for adults. https://www.uptodate.com/contents/search. Accessed Oct. 2, 2020.
6. High-altitude travel & altitude illness. U.S. Centers for Disease Control and Prevention. https://wwwnc.cdc.gov/travel/yellowbook/2020/noninfectious-health-risks/high-altitude-travel-and-altitude-illness. Accessed Oct. 2, 2020.
7. Bardosono S, et al. Pregnant and breastfeeding women: Drinking for two. Annals of Nutrition & Metabolism. 2017; doi:10.1159/000462998.
8. Sterns RH. Maintenance and replacement fluid therapy in adults. https://www.uptodate.com/contents/search. Accessed Oct. 2, 2020.
9. Gordon B. How much water do you need. Academy of Nutrition and Dietetics. https://www.eatright.org/food/nutrition/healthy-eating/how-much-water-do-you-need. Accessed Oct. 2, 2020.
10. 10 tips: Make better beverage choices. U.S. Department of Agriculture. https://www.choosemyplate.gov/ten-tips-make-better-beverage-choices. Accessed Oct. 2, 2020.
11. Thomas DT, et al. Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and American College of Sports Medicine: Nutrition and athletic performance. Medicine & Science in Sports & Exercise. 2016; doi:10.1016/j.jand.2015.12.006.
12. Armstrong LE, et al. Water intake, water balance, and the elusive daily water requirement. Nutrients. 2018; doi:10.3390/nu10121928.