Can Drinking Too Much Water Be Lethal?
Yes. Consuming extreme amounts of water in a short period can cause fatal water intoxication. The condition, also called acute water poisoning, occurs when blood sodium drops dangerously low.
How Much Water Is Considered Lethal?
There is no single safe lethal dose because risk depends on body weight, kidney function, and speed of intake. In documented fatal cases, adults consumed roughly 6 liters or more within a few hours. For a 70 kg adult, drinking more than about 1 liter per hour over several hours may overwhelm the kidneys and trigger hyponatremia.
What Makes Water Intake Dangerous?
Rapid fluid intake dilutes blood sodium, causing cells to swell. Brain swelling can lead to seizures, coma, and death. Symptoms include nausea, headache, confusion, and muscle weakness. The kidneys can normally excrete about 0.8 to 1 liter per hour, so exceeding this rate increases risk.
For more on water safety and kidney function, see Water Intoxication and Hyponatremia.
