Drinking too much water can be dangerous and has proven fatal. This may come as a surprise to dieters or to athletes who are told to be certain to get adequate fluids. The condition caused by drinking too much water is called water intoxication. It can have several possible effects, which can quickly cause an emergency medical situation.

While most people are safe drinking six to eight glasses of water a day, dieters or athletes may try to get an extra edge by drinking more. Especially high performance athletes like marathon runners may over-drink. This can result in an imbalance of the body’s electrolytes. Too much water can quickly deplete electrolytes like sodium compounds.

Rapid intake of too much water floods the inside of cells when sodium is depleted. This sodium depletion, called hyponatremia, can rupture the cells, either from extra pressure on the cells from without, or from pressure within flooded cells. As cells rupture in various parts of the body, certain symptoms emerge with rapidity. Severe vomiting and nausea are common. Headache may occur as the brain swells. A person may be confused or disoriented.

Symptoms progress and may include seizures, and coma. Untreated cases can and have resulted in death. The hazing incident in Chico, California that caused the death of Michael Carrington in 2005 was the direct result of drinking too much water. As well, Carrington was forced to perform exercises in a very cold basement. His death was noted as heart failure from water intoxication.

Runners have also collapsed by drinking too much water quickly. Some sports drinks replace electrolytes as they replace fluids. Yet not all drinks marketed as “sports drinks” are equivalent. Generally, a doctor will be able to tell one which drinks are the best when one is competing in sports. As well runners are now advised to drink when thirsty, instead of getting ahead of thirst. This helps reduce fluid intake to needed amounts in many cases, though most electrolyte replacing drinks are still better choices than water, which might be consumed in excess amounts to satisfy thirst.

Generally too much water is defined as water consumed above what the kidneys can process in an hour. Extremely healthy kidneys would be able to process about 30 ounces (approx .9 liters) of water in an hour. A person with kidney problems or with only one kidney should drink much less, as per doctor’s instructions.

The person with healthy kidneys could develop water intoxication by drinking about 2 to 3 times what the kidneys can process. For a person with kidney problems or with one kidney, too much water might be defined as just an ounce or two over the recommended amounts.

For people with healthy kidneys it should be perfectly safe to drink two cups of water an hour, and for the dieter, even one cup an hour will fulfill requirements for getting plenty of water. However, drinking too much water in rapid succession can prove fatal and should definitely be avoided.