How much water does it take to kill a person? To be honest, not all that much. Paracelsus, the 16th century scientist known largely for establishing the role of chemistry in medicine came up with the concept that everything can be poisonous, or not, depending on the dose. Although modern chemistry has since gravitated away from this belief, the saying still stands true in regards to the earth’s most essential element: water.

It takes about 6 liters of water to kill a 165-pound person, according to a YouTube video recently released by the American Chemistry Society. Surprisingly, death by water, or water intoxication as it’s officially known, happens quite a lot. It’s common among young people who challenge themselves to “water drinking contests,” or athletes who mistakingly over-hydrate while training, Scientific American reported.

Although water is essential to life, when a person drinks too much their blood becomes dangerously diluted of salts. According to Scientific American, this causes a condition called hyponatremia, and severe cases of hyponatremia lead to water intoxication. Some of the main symptoms of water intoxication are headache, fatigue, nausea, vomiting, frequent urination, and mental disorientation

When a person drinks too much water the kidneys cannot flush it out as well and this causes the excess water to enter the cells and cause them to swell. When the brain cells begin to swell the situation can turn lethal fast.

"Rapid and severe hyponatremia causes entry of water into brain cells leading to brain swelling, which manifests as seizures, coma, respiratory arrest, brain stem herniation, and death," M. Amin Arnaout, chief of nephrology at Massachusetts General Hospital and Harvard Medical School told Scientific American.