It’s no secret that water is vital to your health.

In fact, water comprises 45–75% of your body weight and plays a key role in heart health, weight management, physical performance, and brain function (1).

Studies show that upping your water intake may offer many health benefits (2).

However, the amount of water you need is a subject of controversy — and drinking too much can harm your health.

This article examines the benefits and downsides of drinking 3 liters (100 ounces) of water per day.

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Staying well hydrated is incredibly important, as water is needed for a variety of bodily processes and central to nearly every aspect of health and wellness.

In particular, this fluid helps regulate body temperature, transport nutrients, maintain brain function, and enhance physical performance (3).

Not getting enough water can be detrimental, potentially causing side effects like nausea, fatigue, constipation, headaches, and dizziness (4).

Therefore, drinking 3 liters (100 ounces) of water per day may help you meet your hydration needs to support better health.

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Drinking enough water is important for many aspects of health, including body temperature, nutrient transport, and brain function.

Increasing your water intake may aid weight loss.

Drinking water just before meals can be especially useful, as it can promote feelings of fullness and reduce appetite.

One study in 24 people found that drinking 500 ml (17 ounces) of water before breakfast reduced the number of calories consumed by 13% (5).

Similarly, a small, 12-week study showed that drinking 500 ml (17 ounces) of water before each meal as part of a low-calorie diet increased weight loss by 44%, compared with a control group (6).

Drinking water may also temporarily boost your metabolism, which can increase the number of calories you burn throughout the day.

In a small study in 16 people, drinking 500 ml (17 ounces) of water temporarily increased metabolism by 24% over 1 hour, which may aid weight loss (7).

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Water may help you feel full and temporarily increase your metabolism, which may bolster weight loss.

Some research suggests that drinking more water can help keep your skin supple and smooth.

For example, a month-long study in 49 people determined that increasing water intake by 2 liters (67 ounces) per day improved skin hydration, especially in those who typically drank under 3.2 liters (108 ounces) of water daily (8).

Another study in 40 older adults linked higher fluid intake to increased skin hydration and skin surface pH (9).

Skin pH plays an integral role in maintaining your skin’s barrier, which can influence your risk of certain skin conditions (10).

Additionally, a review of six studies found that increased water intake reduced dryness and roughness, increased skin elasticity, and enhanced hydration (11).

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Drinking more water may promote healthy skin by increasing hydration and elasticity while reducing roughness and dryness.

Drinking more water may offer several other benefits as well, including:

  • Increased regularity. Multiple studies associate low water intake with a higher risk of constipation. As such, drinking more water may promote bowel movements (12).
  • Kidney stone prevention. One review of nine studies tied higher fluid intake to a lower risk of kidney stones (13).
  • Headache relief. Research suggests that drinking more water can alleviate headaches caused by dehydration or fluid loss (14, 15).
  • Mood improvement. According to one review, increasing water intake may aid both brain function and mood, especially in children and older adults (16).
  • Enhanced athletic ability. While dehydration can impair exercise performance, replacing fluids after physical activity can increase endurance and decrease exercise-induced DNA damage (17).
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Drinking 3 liters (100 ounces) of water per day may aid bowel regularity, prevent kidney stones, alleviate headaches, improve mood, and strengthen physical performance.

While drinking more water may aid your health, 3 liters (100 ounces) may not be the right amount for everyone.

Currently, no official recommendations exist for the intake of plain water alone. The amount you need is based on several factors, such as age, gender, and activity level (18).

However, there are recommendations for total water intake, which includes water consumed through all foods and beverages, such as plain water, fruits, and vegetables.

A total daily intake of around 2.7 liters (91 ounces) for women and 3.7 liters (125 ounces) for men can meet most adults’ needs (19).

Depending on the other foods and beverages you consume, you may not need to drink 3 liters (100 ounces) of water per day to meet your fluid requirements.

Simply listening to your body and drinking when you feel thirsty is one of the best ways to ensure that you’re staying hydrated. In fact, most people can meet their daily needs by drinking water when they’re thirsty (19).

Notably, some individuals, such as athletes and manual laborers, may need more than 3 liters (100 ounces) of water per day (20).

Drinking too much water can be dangerous

Keep in mind that excessive water intake can be dangerous.

Drinking too much can disrupt your body’s electrolyte balance, leading to hyponatremia, or low levels of sodium in your blood (21).

Symptoms of hyponatremia include weakness, confusion, nausea, vomiting, and — in severe cases — even death (22).

Although your kidneys can excrete up to 20–28 liters (4.5–6 gallons) of water per day, they can only process 800–1,000 ml (27–34 ounces) of water per hour (23).

For this reason, it’s important to spread your water intake throughout the day rather than drink it all in a single sitting. Additionally, be sure to listen to your body and adjust your water intake accordingly if you’re feeling unwell.

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Water needs vary based on numerous factors. As drinking too much water can disrupt your body’s electrolyte balance and lead to hyponatremia, 3 liters (100 ounces) may be too much for some people.

Increasing your water intake may provide many health benefits, especially for weight loss and skin health.

While drinking 3 liters (100 ounces) daily may help you meet your needs, it isn’t necessary for everyone. In fact, drinking too much water can be dangerous.

To ensure you’re staying hydrated, drink when you feel thirsty and always listen to your body.