We cannot live without water, but it can harm our bodies if we drink too much of it. Absorbing more water than the kidneys can handle can lead to low blood sodium levels. 

This condition is called Overhydration or water intoxication and, in extreme cases, can cause brain damage, coma, and even death.

The average adult needs to drink 3 to 4 liters of water per day, while the kidneys with normal functioning can only process a liter of water per hour.

When there is more water, it remains in the body’s cells, provoking their swelling. This process leads to water intoxication and low blood sodium levels, increasing blood pressure. 

Swelling in the body can be corrected, but if excess water is in the muscles, body fat, or brain, it can lead to serious health problems due to their rigid structure.

Table of Contents

Causes of Overhydration

Overhydration is a fluid imbalance. This condition occurs when the body gets or retains too much fluid. Drinking too much water or your body and not excreting fluids will cause fluid to build up. 

Each individual’s water needs can vary, depending on gender, weather, activity level, and overall health condition. Situations such as a hot environment and illness with fever require more fluid intake than usual.

Certain health conditions and taking certain medications can also cause Overhydration. These health conditions include heart failure, liver disease, kidney problems, non-steroidal anti-inflammatory drugs, and diabetes.

1. Increased fluid intake

glasses - overhydration
A lot of glasses are filled with water. Do not drink this much water at once. (source)

This condition occurs when a person drinks more water than the kidneys can excrete through urine. With the fluid imbalance in the body, more water will collect in the body.

2. Fluid Retention

This condition occurs when the body cannot get rid of water optimally and cause the body to retain moisture. This condition can change in someone who has impaired kidney function.

Symptoms of Water Intoxication

Drinking plenty of water increases the amount of water in your blood volume. This water can dissolve electrolytes, especially sodium, present in the blood.

When the sodium amount in the body falls below 135 mmol / L, the condition is known as hyponatremia.

Sodium is needed to balance fluids between the inside and outside of cells. When sodium levels drop due to excessive water intake, the body suffers from inflammation (swelling of brain cells).

If the brain cells are swollen, it can lead to dangerous and potentially life-threatening consequences. When the brain cells swell, the pressure inside the skull increases, causing the first symptoms of water intoxication, which include:

  • Headache
  • Nausea
  • Vomiting
Headache - overhydration
Man with a headache (source)

In severe cases, more severe symptoms may appear, such as:

  • High blood pressure
  • Confusion of consciousness
  • Double vision
  • Drowsiness
  • Labored breathing
  • Muscle weakness and spasms
  • Failure to identify sensory information

Excessive accumulation of fluid in the brain cells is called cerebral edema, which can affect the brain and cause the brain to be dysfunctional. Water intoxication or poisoning can cause seizures, brain damage, coma, and even death in severe cases.

Fatal Consequence

It is challenging to drink too much water; however, deaths have been reported due to this condition. Many cases of water poisoning have been reported in US soldiers. One report indicated 17 soldiers who developed hyponatremia due to excessive water intake. 

Another report describes three soldiers dying due to hyponatremia and cerebral edema. These deaths occurred due to drinking 2.5-5.6 gallons (10-20 liters) of water in just a few hours.

The symptoms of hyponatremia can be mistaken with signs of dehydration. A soldier was mistaken for suffering from dehydration and heatstroke, died of water intoxication due to repeated oral hydration.

Water intoxication also occurs during sports activities, especially in endurance sports. Overhydration is common in these activities as a means of staying hydrated.

For this reason, hyponatremia often occurs in athletes during significant sporting events such as Marathon. At the 2002 Boston Marathon event, 13% of participants developed symptoms of hyponatremia.

0.06% showed symptoms of critical hyponatremia with sodium levels less than 120 mmol / L. Unfortunately, some cases of water intoxication at these sporting events have resulted in death.

The test of a runner who died after a marathon showed that his sodium level was below 130 mmol / L. He developed hydrocephalus and a hernia of the brain stem, which led to his death.

Psychiatric patients tend to drink excessive water can also be observed in psychiatric patients, especially in people with schizophrenia.

study of 27 people with schizophrenia who died young showed that five died from self-induced water intoxication.

Overhydration Occurrence

Gallon - overhydration
One Gallon of water is 3.7 – 4.5 liters (source)

Excessive hydration and water intoxication occur when you drink more water than the kidneys can excrete in urine. The amount of water you drink isn’t the only factor. How long you drink water also matters.

The risk of developing water intoxication or Overhydration is greater if you drink a lot of water in a short period. The risk decreases if you consume the same amount for a more extended period.

Symptoms of hyponatremia can arise from as little as 0.8-1 gallons (3-4 liters) of water drunk in a short amount of time.

The kidneys can handle about 5.3-7.4 gallons (20-28 liters) of water per day, but they cannot excrete more than 27-33 ounces (0.8-1.0 liters) per hour.

Therefore, to avoid the symptoms of hyponatremia, you shouldn’t drink more than 0.8-1.0 liters of water per hour on average.

Many reported water intoxication cases resulting from drinking large amounts of water over a short period. For example, soldiers developed symptoms after drinking half a gallon of water (1.8 liters or more) an hour.

Another report showed the development of hyponatremia with a water intake of 10-20 liters in just a few hours. Water intoxication and prolonged hyponatremia developed in a healthy 22-year-old male prisoner after drinking 6 liters of water in 3 hours.

nine-year-old girl who drank nearly a Gallon (3.6 liters in total) of water in 1–2 hours developed water intoxication.

A signal from the body

Before reaching the extreme of suffering a disease, the body signals our water level. One of the primary signals is the color of urine.

A straw yellow tone indicates that we are doing the right thing; if it is rather dark, it probably denotes a lack of hydration, while if it is colorless, it means we are drinking in excess.

Another way to identify it is by the times you need to go to the bathroom. Between 7 and 8 times is expected; more than ten could be a warning that we should cut back on fluids. 

In addition, some ailments cause more thirst than usual such as Congestive heart failure, kidney and liver problems, antidiuretic hormone malfunction syndrome, taking non-steroidal anti-inflammatory drugs, or uncontrolled diabetes. 

Schizophrenia, ecstasy, antipsychotic medications, and diuretics are also susceptible to causing excessive thirst.

An appropriate amount of water to drink

amount of water - overhydration
Amount of water you should drink per day (source)

There is no specific amount for how much water you need to drink per day. This amount is different for every person. To determine how much water you need, consider your body weight, physical activity level, and climate.

The Institute of Medicine (IOM) proposes an adequate water intake per day for men to be 125 ounces (3.7 liters) and 91 ounces (2.7 liters) for women.

However, these recommendations include water from drinks and food. Some people like to follow the 8 x 8 Rule, which recommends drinking eight glasses of water a day. However, this rule is not based on research.

A good and easy rule of thumb is to listen to your body and drink water only when you are thirsty. This amount of drinking water should be sufficient to maintain a good hydration level.

People at risk of Overhydration

If a healthy person slightly exceeds the volume of water, then he will get off with just frequent visits to the restroom. 

The kidneys can cope with the excretion of 800-1000 ml of fluid in an hour. Excess water in the body is a problem that can be seen in:

1. Athletes

Athletes - overhydration
Athletes running during hurdle events are probably dehydrated and exhausted (source)

There are cases of runners dying from water poisoning; one of them is Cynthia Lucero, a participant in the Boston Marathon, which took place in 2002.

2. People on Diet

People who are on a diet and taking fat-burning drugs increase their thirst. The complete absence of salt in the diet, muffling of hunger with water, removing toxins, and burning fat with excess water can negatively affect the body’s functioning.

3. Lifestyle

Regulars of various parties and nightclubs are more prone to Overhydration. Dancing in combination with alcohol consumption causes increased thirst.

4. Addiction

Drug addicts and people with alcohol dependence can develop Overhydration. Addictive substances increase thirst.

5. Elderly People

Closer to old age, the body gets rid of excess water less efficiently because the volume of the bladder, the number of renal glomeruli in the corresponding tubules, and the number of sweat glands decrease.

Treatment of Overhydration

Regardless of the cause of excessive hydration, fluid intake should generally be restricted (but only as per medical advice). 

Drinking less than a liter of fluid a day usually improves within a few days. Excessive hydration occurs with excess blood volume due to heart, liver, or kidney disease; it is also helpful to restrict sodium intake, as sodium causes water retention.

Medications that tend to cause excessive hydration are discontinued. Sometimes a doctor prescribes diuretics to increase the excretion of sodium and water in the urine. 

Other medications can increase water excretion and sometimes treat excessive hydration when blood volume is average. Typically, these medications are used when hospitalized and can be closely monitored.


You have to take water when you are thirsty but not beyond the human body’s capabilities. Isotonic drinks are a good option for long-duration exercises: they replenish the levels of sodium and other electrolytes lost during exertion.

On the other hand, to compete in tests with this type of physical demand, the best thing is an excellent professional preparation that teaches how to measure hydration during exercise and regulate sodium levels.

The regular sodium intake should be between 1-1.5 grams of salt for each liter of non-energy drink (1/5 – 1/3 of a teaspoon) and 0.5-0.7 grams of salt/liter in the case of energy drinks.


Drinking adequate water keeps you healthy, but excessive drinking can cause water poisoning. There is a myth that we should drink 8 to 10 glasses of water a day. 

However, the water necessity may vary from one individual to another. So the best way to fulfill the water demand of your body is drinking when you feel thirsty. 

(Last Updated on November 21, 2021 by Sadrish Dabadi)

Ankur Pradhan holds a bachelor’s degree in education and health and three years of content writing experience. Addicted to online creative writing, she puts some of what she feels inside her stormy heart on paper. She loves nature, so she is trying to motivate people to switch to alternative energy sources through her articles.