Drinking an excessive amount of water in a short period can lead to water intoxication (also called water poisoning or hyponatremia), which can be fatal. The kidneys can typically process about 1 liter of water per hour; consuming more than this over several hours risks overwhelming the body's electrolyte balance, especially sodium levels
. Symptoms of water intoxication usually begin after drinking more than 3 to 4 liters of water within a few hours. Severe cases have been reported with consumption of about 6 liters in 3 hours, which has caused death in humans
. The condition causes sodium in the blood to become diluted, leading to swelling of cells, including brain cells. Brain swelling increases pressure inside the skull, potentially causing headaches, confusion, seizures, coma, and death
. In summary:
- Drinking around 6 liters (about 1.5 gallons) of water in a short time (e.g., 3 hours) can be fatal for an average adult
- The kidneys can only remove about 0.8 to 1 liter per hour, so drinking more than this rate increases risk
- Water intoxication symptoms start around 3-4 liters consumed rapidly and worsen with higher intake
- The key danger is dilution of sodium (hyponatremia), causing brain cell swelling and potentially death
Therefore, while water is essential for health, drinking excessive amounts very quickly can be deadly due to water intoxication. The safe approach is to drink according to thirst and avoid consuming large volumes in a short period.
