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

Michael Garrico
Published by Michael Garrico | Co-Founder & Marketing Director
Last updated: November 23, 2023
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Being in the fitness industry for almost a decade, 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 may enhance your metabolism, give you an energy boost, improve skin quality, aid digestion, and have many other benefits.
  • However, if taken in a short time, it could trigger hyponatremia (too low sodium levels in the blood) and cause feelings of dizziness and nausea, or even lead to some more severe health conditions.
  • Some tips to make you drink enough water during the day and prevent dehydration include drinking after a bathroom break, before a meal, flavoring your water, or setting a drink water reminder.

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 [1].

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

Enhancing Metabolism

Water, in general, 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

As the vast majority of water is absorbed in the small intestine, water is vital for keeping things going through your gastrointestinal tract.

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?

It can be dangerous to drink a gallon of water a day only if you have congestive heart failure or end-stage kidney disease.

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.


  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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