3 Benefits of Drinking a Gallon of Water a Day (And Dangers)

Christiana Mikesch, CPT
Published by Christiana Mikesch, CPT | Senior Coach
Last updated: December 28, 2023
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As a certified personal trainer, I’m well aware that proper water intake is crucial for physical performance, weight loss, and overall health.

While drinking water when you’re thirsty is a reflex, drinking a gallon requires planning, determination, and effort. But is it worth it?

I spent a few days reading the relevant scientific literature on the subject, and I analyzed the data with a medical professional to uncover if there’s a scientifically supported benefit to drinking a gallon of water a day.

Quick Summary

  • Drinking a gallon of water daily can enhance metabolism, boost energy, improve skin quality, aid digestion, and offer numerous other health benefits.
  • However, consuming a gallon of water in a short time may lead to hyponatremia, causing symptoms like dizziness, nausea, and, in severe cases, more serious health conditions.
  • A study from 2003 found on the Journal of Clinical Endocrinology & Metabolism website demonstrated a 30% increase in metabolic rate after drinking 20 oz of chilled water, highlighting the potential weight loss benefits of increased water intake.
  • From my perspective as a fitness professional, drinking a gallon of water a day, when done responsibly, can be a highly beneficial practice for overall health and well-being.

What Benefits a Gallon of Water May Provide?

A woman doing yoga while drinking water

Drinking a gallon of water may provide benefits like headache prevention, weight loss and improved brain function. Moreover, this may provides numerous benefits to the human body, including improved hydration, enhanced digestion, and better overall functioning.

Even though conventional wisdom says you should drink eight glasses of water a day, it’s definitely not a one-size-fits-all type of solution. The exact amount of water consumption necessary to maintain healthy hydration levels largely depends on age, size, sex, and activity level.

Since proper hydration is crucial as your body is 55-65% water, consuming larger amounts (a gallon) will be able to prevent even mild dehydration, as well as bring other important health benefits, according to an article from the National Center for Biotechnology Information website [1].

Let’s take a more detailed look at those benefits.

Enhancing Metabolism

According to another study found on the National Center for Biotechnology Information website, water is responsible for many energy-related tasks, and drinking it stimulates your heat production (thermogenesis) and increases your body temperature [2].

It’s no surprise that a study from 2003 showed a boost in metabolic rate by 30% after an hour of drinking around 20 oz of chilled water [3]. This essentially means drinking water is highly beneficial for weight loss, as boosting your metabolism means burning more calories and, ultimately, losing fat.

Aids Digestion

A person with good digestion because of hydration

From my nutritional counseling sessions, I've learned that adequate water intake is essential for smooth digestion. It helps in the absorption of nutrients in the small intestine and prevents issues like constipation, enhancing overall digestive health.

Therefore, when you don’t take enough water, your stool hardens, becomes dry, and causes uncomfortable constipation [4].

Suppresses Cravings

Dehydration often makes you confuse thirst for hunger, as the lack of electrolytes like potassium and sodium might make you crave food between meals. Water is usually electrolyte-rich, which means adequate hydration can suppress food cravings.

Also, one study suggests drinking only 16 oz of water before eating breakfast, lunch, and dinner can provoke appetite suppression and prevent you from overeating [5]. So drinking a gallon daily may help you lose a few pounds even on its own.

Other benefits 

A person looking up the benefits of drinking water

The benefits of drinking a gallon of water a day also include better brain activity, and that’s no surprise either since the brain is 3/4 (75%) water. Research from 2019 showed that rehydration improved short-term memory, attention, and cognitive performance in general [6].

Staying hydrated keeps the water balance system active which could help you eliminate waste bodily fluids and flush toxins. Moreover, that increased water balance will most likely prevent headaches, improve physical performance, and alleviate dry skin [7].

Could It Be Dangerous to Drink a Gallon a Day?

In my years of training, I've advised clients that drinking a gallon of water per day is generally safe, except for those with specific health conditions like congestive heart failure or kidney disease. It's important to listen to your body and adjust your water intake accordingly.

Otherwise, you can freely drink a whole gallon as it won’t harm you. See, your body will quickly eliminate too much fluid when your organs function properly, especially your kidneys.

“When we drink more than what we need — or don’t drink as much as we need — in healthy individuals, it puts a little stress on our kidneys, but our kidneys are very good at trying to help us return to balance, so generally it will be ok.”
- Kelly Anne Hyndman, PhD

However, this doesn’t mean overhydration is a myth. When this happens, your blood becomes ‘‘watered down’’ as sodium levels in your body drop too low, causing the dangerous state called hyponatremia [8].

Symptoms include headaches, confusion, muscle weakness, seizure, or even coma. Luckily, it happens extremely rarely, and you would have to drink between 1.5 and 2.5 gallons of water in a few hours to trigger it.

On the other hand, if you have kidney stones or a similar medical condition, the general recommendation is to drink even more than your daily needs to clear out the waste products.

How To Stay Hydrated?

A person working out on a treadmill drinking from a water bottle to stay hydrated

To stay hydrated, you should apply some simple tricks like drinking a glass of water after each bathroom break or before each meal.

One easy way would be to eat more fruits and vegetables, especially those with higher water content, like cucumber, watermelon, or pineapple.

If eating instead of drinking water sounds impractical, you could just set your app to remind you to drink water and hydrate regularly.

But if you are serious about drinking a gallon of water daily, in the beginning, you will need to plan for a steady supply of extra water consumption.

The first thing you need is your willpower, which is why you should set a specific goal (the timing and the number of glasses at each point of the day).

To accomplish this goal, it would be helpful to develop the habit of drinking a glass of water after every bathroom break to replenish the fluid levels.

Also, you could do the same before every meal, which will help you suppress your appetite and lead to weight loss.

Lastly, if you aren’t a fan of plain water, you can carry a bottle of water enriched with some fruity or herb flavors to staying hydrated properly.

However, you should always avoid energy drinks, sugary drinks, or sports drinks.


What Happens if You Drink a Gallon of Water a Day for 30 Days?

If you drink a gallon of water a day for 30 days, you will probably feel you have more energy, less craving throughout the day, and an improved skin appearance. These effects may not be the same for everyone since many factors and bodily functions determine water intake requirements.

Will I Gain Weight if I Drink a Gallon of Water?

Yes, you will gain weight temporarily if you drink a gallon of water, but that weight gain is called ‘‘water-weight’’, and it doesn’t burden your body for long. In 24 hours, excess fluids are excreted, and you will either have a net loss or a stable weight for the day.

How Does Hydration Affect Cognitive Function?

Adequate hydration has a significant impact on cognitive functions, including improved memory, enhanced focus, and mood stabilization. Dehydration can lead to decreased concentration, increased fatigue, and mood disturbances.

Can Increased Water Intake Improve Skin Health?

Drinking sufficient water can greatly improve skin health by enhancing hydration, reducing dryness, and potentially alleviating skin conditions like eczema. Proper hydration helps maintain skin elasticity and can contribute to a healthier, more radiant complexion.

What Is the Impact of Hydration on Kidney Health and Function?

Proper hydration is crucial for kidney health as it aids in the filtration of waste products and reduces the risk of developing kidney stones. Adequate water intake ensures efficient functioning of the kidneys and helps maintain overall urinary tract health.

How Does Hydration Enhance Athletic Performance?

Staying well-hydrated is essential for enhancing athletic performance, as it affects endurance, strength, and recovery. Dehydration can lead to decreased performance, increased fatigue, and a higher risk of heat-related illnesses during physical activity.

Why Is Balancing Electrolytes Important When Drinking a Lot of Water?

When consuming large amounts of water, it's important to maintain a balance of electrolytes in the body to prevent conditions like hyponatremia, where low sodium levels can lead to serious health issues. Electrolyte balance is key to proper bodily functions, especially during intense physical activity or high water intake.


  1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2929932/
  2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3762624/
  3. https://academic.oup.com/jcem/article/88/12/6015/2661518
  4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3206564/
  5. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4121911/
  6. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6603652/
  7. https://pubmed.ncbi.nlm.nih.gov/15182398/
  8. https://my.clevelandclinic.org/health/diseases/17762-hyponatremia
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About The Author

Christiana Mikesch, CPT
Senior Coach
Christiana Mikesch, CPT is a personal trainer and author with contributions to publications like the Chicago Tribune and Yahoo. She emphasizes a holistic approach to weight loss, combining an energy-fueling diet, goal-oriented workouts, and daily habits. Her approach avoids short-term goals and fosters a lifelong commitment to health and well-being.
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Lisa Lorraine Taylor, BSc, CPT
Staff Writer
Lisa Lorraine Taylor, BSc, CPT holds a BSc degree in Holistic Nutrition from Clayton College of Natural Health and is the owner of Taylor Made Fitness. Her philosophy centers on cutting through the hype and misinformation surrounding dietary supplements, focusing instead on practical, science-backed strategies for health and weight loss.
Learn more about our editorial policy
Dr. Harshi Dhingra, MBBS, MD is a published peer-reviewed author and renowned physician from India with over a decade of experience. With her MBBS from Bharati Vidyapeeth and an MD from Rajiv Gandhi University, she actively ensures the accuracy of online dietary supplement and medical information by reviewing and fact-checking health publications.
Learn more about our editorial policy

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