How Much Water Should You Really Drink A Day?

About 50% to 70% of human body weight is water. Without water, we cannot survive. Every cell, tissue, and organ in our body depends on water for its normal functions. Scientific evidence shows that the benefits of drinking water include: 

• Regulates body temperature

• Aids with digestion

• Eliminates wastes through sweating, urination, and bowel movements

• Lubricates joints

• Protects vital organs and sensitive tissues such as the brain and spinal cord

• Maintains fluid and water balance

• Helps organs function properly

• Makes chemicals such as hormones and neurotransmitters

General Guidelines for Daily Water Intake

According to the U.S. National Academies of Sciences, Engineering, and Medicine, the daily fluid intake for an average adult living in a temperate climate should be: 

• 3.7 liters (15.5 cups) for men 

• 2.7 liters (11.5 cups) for women

For adults 51 years and older, the National Academy of Medicine recommends a daily water intake of 3 liters (13 cups) for men and 2.2 liters (9 cups) for women in this age group. This includes water, other fluids, and water content in foods. Approximately 20% of daily fluids are obtained from food and the rest from water intake and other beverages.

Older adults who stay well-hydrated are at lower risk for urinary tract infections, constipation, falls, and other health risks.

Is eight glasses of water enough to drink daily?

It’s common advice to drink eight glasses of water daily. Assuming each glass contains eight ounces of water, eight glasses of water will be equal to 64 ounces or 1.9 liters of water. It’s a reasonable goal to set. Keep in mind that some people may need more than 8 glasses and others less than 8 glasses daily, depending on various factors such as regional climate, age, sex, activity levels, and health history.

Factors That Affect Fluid Intake Needs

Activity Level

Physical activities that make you sweat cause you to lose water. You therefore need to increase your total fluid intake to make up for this fluid loss. It is recommended to drink water before, during, and after exercise to stay adequately hydrated.

Climate and Temperature 

Humid or hot weather can cause increased sweating, requiring additional hydration. High altitudes and exposure to extreme cold can also lead to dehydration. You should, therefore, drink more water if you are in extreme temperatures.

Health Conditions and Pregnancy 

Certain health conditions, such as fever, vomiting, and diarrhea, can cause you to lose fluids. You should drink additional fluid and oral rehydration solutions to replace lost fluids and electrolytes as directed by your healthcare provider. 

Other health conditions in which you may need to drink more water include urinary tract infections and kidney disease, for example, kidney stones. Also, women who are pregnant or breast-feeding may need to drink additional fluids to stay hydrated.

Medications

Certain medications, such as diuretics (water pills), blood pressure medicines, diabetes medications, and psychiatric medicines, can make you pee more, thereby increasing fluid loss from your body. Talk to your doctor about rehydrating while on such medicines.

Signs of Dehydration

The absence of enough water in the body is called dehydration. Dehydration can cause symptoms such as: 

• Headache

• Fatigue

• Dizziness or lightheadedness

• Weakness

• Delirium or confusion

• Dry mouth 

• Cough

• Increased heart rate 

• Low blood pressure

• Loss of appetite 

• Sugar cravings

• Flushed skin

• Muscle cramps

• Swelling of the feet

• Chills or heat intolerance

• Dark yellow urine (normal urine is clear to pale yellow)

• Constipation

Long-Term Health Risks of Chronic Dehydration 

Severe and/or long-term dehydration can lead to serious health complications such as: 

• Electrolyte imbalances

• Heatstroke

• Kidney stones and kidney failure

• Shock

• Coma

• Death

Health Risks Associated with Overhydration 

While drinking plenty of water has many health benefits, overhydration (or too much water) can also cause problems such as hyponatremia. 

Hyponatremia is the medical term for low blood sodium levels. It is a type of electrolyte imbalance in which the sodium levels in blood fall below 135 mEq/L. One of the causes of hyponatremia is water intoxication which occurs when the amount of water intake exceeds the amount of water that can be eliminated by the kidneys. 

Drinking more than 3 liters of water within a few hours or more than 10 liters of water daily for several days can lead to hyponatremia.

Signs and symptoms of hyponatremia include nausea, vomiting, headache, drowsiness, confusion, fatigue, low energy levels, restlessness, irritability, muscle spasms, cramps or weakness, convulsions, and coma. 

How to Determine Your Optimal Daily Water Intake 

Calculating Your Baseline Water Requirement

There are a few different ways to calculate your daily water requirement. 

Body Weight

Before factoring in the levels of physical activity, you can use this equation to establish a baseline on how much water you should be drinking daily: 

Your weight (in pounds) x 0.5 = The amount of water (in ounces) you should drink 

For example, if you weigh 150 pounds (lbs), 150 lbs x 0.5 = 75 oz, which means you should drink 75 oz or 2.2 liters of water daily.

Keep in mind that this formula is a general guideline and your fluid intake will vary depending on other factors such as activity level, climate, and health status.

Physical Activity 

The American College of Sports Medicine (ACSM) recommends adding 12 ounces of water to your daily intake for every 30 minutes of physical activity, which is often consumed during the activity or exercise. Therefore, if your recommended daily water intake is 2 liters and you exercise for 1 hour, you should drink an additional 24 oz or 700 mL of water to stay hydrated. To adequately stay hydrated throughout your exercise, the ACSM also advises you to drink 0.5 liters (17 ounces) of water approximately 2 hours prior to exercise. Endurance athletes may need to drink larger quantities of water to replace fluid loss due to sweating.

Climate and Weather

You may need to drink up to 3 liters of water on hot or humid days to prevent dehydration. Remember not to drink it all at once. Make sure you space out your fluid intake throughout the day.

The Centers for Disease Control and Prevention (CDC) recommends drinking 8 ounces (1 cup) of water every 15-20 minutes if you are working outdoors in the heat. This is equal to 24-32 ounces (3-4 cups) per hour. Do not drink more than 48 ounces (6 cups or 1.4 liters) per hour of water, sports drinks, energy drinks, etc. — this can put you at risk of water intoxication.

Special Adjustments

The American Pregnancy Association recommends that most pregnant and breast-feeding women should drink an additional 24-32 ounces (700 mL to 950 mL or 3-4 cups) of water, or a total of 64 to 96 ounces of water  every day. Your healthcare provider may ask you to increase your water intake if you have certain health problems such as bladder infections or kidney stones. 

Other Sources of Hydration 

Other Beverages That Contribute to Hydration 

Drinking water can get boring, and meeting your daily hydration needs can feel like an uphill task. Other healthy alternatives for staying hydrated include:

• Green smoothies made using lettuce, kale, and spinach

• Sugar-free juices such as watermelon juice and cucumber juice

• Coconut water

• Milk

• Broths

• Homemade ice pops

Avoid sweetened juices, energy drinks, and other sweet drinks that are calorie-rich, especially if you are trying to lose weight. Even though they provide some hydration, it’s best to avoid caffeinated beverages such as teas, coffees, and colas. Even caffeinated drinks have calories, and they can have a diuretic effect (make you pee more and lose water, resulting in dehydration). 

Foods with High Water Content 

Another way to consume water is to eat more water-rich foods such as watermelons, melons, oranges, peaches, cucumbers, celery, and lettuce.

Practical Tips for Increasing Daily Water Intake

Set Realistic and Achievable Goals for Drinking Water

If you have decided to drink more water, the first step is to understand your daily fluid needs. Next, you should set a daily goal that is specific and attainable. For example, don’t just say, “I’ll drink more water.” Say, “I’ll drink 2.5 liters of water every day.” Choose a goal that is achievable. If your current water intake is 0.5 liters a day, aiming to suddenly increase it to 3 liters a day can be overwhelming.

Track Your Water Intake

A proven way to ensure adequate hydration is to track how much water you are drinking on a daily basis. There are various ways to do this, such as apps that remind you to drink water and also let you log how much water you’ve consumed. 

Setting reminders on your phone can help you stay on track with adequate water consumption. Keeping a water bottle with you is helpful to ensure water is available. Investing in a transparent water bottle with graduation marks is also a good idea, as these bottles can help you visualize how much more water you need to drink to meet your goal. This will encourage you to drink water throughout the day and achieve your fluid intake goal.

Make Water More Appealing 

Add Flavor to Water

Drinking water is the best way to stay hydrated. Water has zero calories and is free or low-cost. If you are bored of drinking plain water, you can make it more interesting by 

adding natural flavors. For example, slices of lemons or oranges or herbs such as mint or rosemary. 

Ideal Temperature of Drinking Water

Make sure you drink water at a palatable temperature. For example, drinking cool water is more appealing in the summer months, while sipping on warm water can be comforting in colder weather. In terms of the best temperature for water benefits, room temperature or slightly cool water is considered ideal.

How Much Water Should I Drink Everyday?

Thirst is a Good Indicator

One of the most important things to remember is to drink before you start feeling thirsty. Thirst is a sign of dehydration, so if you’re feeling thirsty, you already have some catching up to do.

Drink Water Throughout the Day

Research shows that drinking small amounts of water at frequent intervals is more effective than drinking large amounts of water infrequently. Therefore, it’s important to space out your water consumption throughout the day. Consider drinking water when you wake up in the morning, with meals, before, during, and after exercising, and of course, whenever you feel thirsty.

Tailor Your Water Intake to Personal Health Goals 

Staying hydrated can improve physical performance and treat health problems such as headaches and constipation. If you suffer from symptoms that could be linked to dehydration, set a goal to drink more water and see if you feel better.

Seek Professional Advice

Dehydration can lead to very serious health complications. It’s important to seek professional medical care if you have signs and symptoms of dehydration. For example, if your urine goes from light yellow to dark yellow, call your doctor immediately. Or if you normally rarely feel thirsty but notice a sudden change in your thirst levels.

Frequently Asked Questions

Is 3 cups of water a day ok?

Three cups of water a day is not enough. It is equivalent to about 700 mL or 24 oz of water, which is lower than the recommended daily water consumption for most people. Drinking only 3 cups of water per day may lead to dehydration.

How much water should a 5 foot 3 woman drink a day?

Height does not directly affect the amount of water a person should drink. Factors such as age, gender, weight, activity level, climate, and health status can be used to calculate daily water intake.

How much water should I really drink per day?

Eight glasses daily (with 8 ounces of water in each glass) is a good goal to start with; this will give you 64 ounces (about 1.9 liters) of water daily. However, the recommendations are for a healthy adult to drink 2.7 liters (women) and 3.7 liters (men) every day. How much water kids drink depends on age and other factors.

Is drinking 3 liters of water a day too much?

Drinking three liters of water daily is adequate for someone living in a hot, humid climate or engaging in regular physical activity. However, three liters of fluids may be too much for a person who has heart failure, kidney or liver disease. 

Your healthcare provider can help you decide your daily water intake goal. Whatever your daily water intake goal, it’s important to space it out and not drink all of it in one sitting.