How Much Water Is Too Much?

Water is a critical component of a healthy, functioning body and it is important to stay hydrated. However, you should keep in mind that too much of a good thing is still too much.

Excessive fluid consumption can actually work against your wellbeing and contribute to health problems. Fluid overload, or "water intoxication," can lead to serious health consequences, namely swelling of the brain, brain injury, and potentially stroke, which can ultimately cause disability or even death.

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The effects of excessive water consumption are not just due to the total amount consumed—water toxicity can also be a result of drinking too much water too quickly. People may just experience mild effects of "water overdose" at first, with more dangerous effects to follow if consumption continues.

The Consequences of Drinking too Much Water

Your body works to maintain normal function despite the regular variations in fluid levels that you experience throughout the day. The first way your body manages water overload is by simply getting rid of the excess fluid through urine. This means if you drink too much fluid, you will balance out your body's fluid by urinating more. For the most part, your body can keep up if you repeatedly drink more water than you need.

Central Nervous System Symptoms

However, the rapid consumption of large amounts of water can overwhelm the body’s natural ability to maintain normal fluid balance. This causes excess fluid to enter the brain, resulting in brain swelling. Symptoms of brain swelling may include:

  • Confusion
  • Headache
  • Drowsiness, lethargy
  • Dizziness (vertigo): Reported in 14% of patients with severe hyponatremia
  • Severe symptoms including sudden unexpected loss of consciousness, seizures, or stroke.

When the body takes in extreme amounts of fluid, the excess water literally flows into the brain cells through a process called osmosis. This causes brain tissue compression and lack of normal function. Brain cells may experience a disruption to their normal calcium and sodium concentration and begin to function abnormally. This results in the symptoms that may include lightheadedness, dizziness, or confusion.

Hyponatremia, having an abnormally low amount of sodium in the bloodstream, can contribute to the symptoms of nausea, vomiting, or muscle cramps. The condition can also cause brain cell death from physical compression and electrolyte/water imbalances. Hyponatremia can be very difficult to manage medically because it progresses so rapidly and the damage is so severe.

Causes of Drinking Excessive Amounts of Water Too Fast

There are a few circumstances that may prompt an excessive amount of water drinking and potentially overdose:

Health Cleanse

Dieters and other people trying to lose weight may incorrectly assume that drinking an excessive amount of water will "flush" the unhealthy toxins in their body out. While water can certainly help promote balance, you don't want to overdo it.

The ideal amount of fluid consumption for an average person should be between 9 to 12 cups per day, depending on activity levels and some other factors.

In general, thirst is a reliable indicator of the body’s water requirements. Some health conditions such as diabetes and kidney disease may disrupt your normal thirst mechanism and necessitate a consultation with a dietitian or healthcare provider to set guidelines for fluid intake.


It is normal for athletes to drink fluid in order to replenish and cool off during and after a training session, and it is important for the body to stay hydrated during exercise. However, in the setting of extreme physical exertion, thirst may not be the best guide.

Hyponatremia due to excessive drinking and sodium loss through sweating has been seen among marathon and triathlon participants. Devoted athletes who work out beyond moderate levels should obtain professional guidance regarding appropriate fluid replenishment.

Water Games

These activities often seem silly or harmless to young people. Yet some actions that seem innocuous may be quite dangerous. Preschool-aged children and older kids—even as old as college-aged young adults—may think it is funny to challenge each other to drink large amounts of water or other liquids (such as alcohol, which contains mostly water) quickly. But these fun games have unfortunately been known to harm some of the kids who participate in them.

Water overload has been responsible for incidents of brain damage and death in children, teenagers, and young adults who play games involving exaggerated fluid drinking or who use rapid consumption of excess water or fluid in hazing and initiation rituals. The outcome is usually shocking to young witnesses, which can further delay appropriate medical attention and treatment. Thus, the damage may be permanent paralysis, mental incapacity, or death.


If you are drinking an excess amount of water and still feeling very thirsty, then this could be a sign of diabetes (a problem with your pancreas that results in a buildup up blood sugar). Your body manages the excess blood sugar in a very complex way, and frequent urination and constantly feeling thirsty are among the earliest signs of diabetes. Speak with your healthcare provider as soon as possible if you feel you are experiencing this situation.

A Word From Verywell

Water consumption is an important part of healthy body function and balance, and drinking water is generally good for you. That being said, drinking an excessive amount of water can have health consequences ranging from mild to serious. The key to a healthy lifestyle is balance and moderation. Take care of your health by seeking out trustworthy and reliable health information sources.

6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  3. Rondon H, Badireddy M. Hyponatremia. In: StatPearls. Treasure Island (FL): StatPearls Publishing.

  4. Popkin BM, D'Anci KE, Rosenberg IH. Water, hydration, and healthNutr Rev. 2010;68(8):439–458. doi:10.1111/j.1753-4887.2010.00304.x

  5. Danz M, Pöttgen K, Tönjes PM, Hinkelbein J, Braunecker S. Hyponatremia among triathletes in the Ironman European championship. N Engl J Med. 2016 Mar 10;374(10):997-8. doi:10.1056/NEJMc1510409

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By Heidi Moawad, MD
Heidi Moawad is a neurologist and expert in the field of brain health and neurological disorders. Dr. Moawad regularly writes and edits health and career content for medical books and publications.