Too Much of a Good Thing Can Kill You
Dr. Mercola

A new review of three deaths of US military recruits highlights the dangers of drinking too much water.

The military has traditionally focused on the dangers associated with heat illness, which has killed a number of healthy, young enrollees. However, pushing the need to drink water too far can also have deadly consequences.

The risk has always been not drinking enough. And then people who aren’t medically attuned get overzealous, inducing recruits to drink amounts of water that endanger their health.

In September 1999, a 19-year-old Air Force recruit collapsed during a 5.8-mile walk, with a body temperature of 108 degrees Fahrenheit. Doctors concluded he had died of both heat stroke and low blood sodium levels as a result of overhydration.

During January 2000, a 20-year-old trainee in the Army drank around 12 quarts of water during a 2- to 4-hour period while trying to produce a urine specimen for a drug test. She then experienced fecal incontinence, lost consciousness and became confused, then died from swelling in the brain and lungs as a result of low blood sodium.

In March 2001, a 19-year-old Marine died from drinking too much water after a 26-mile march, during which he carried a pack and gear weighing more than 90 pounds. Although he appeared fine during the beginning stages of the 8-hour walk, towards the end he began vomiting and appeared overly tired.

He was then sent to the hospital, where he fell into a coma, developed brain swelling and died the next day. It is unclear how much water he drank during the march, but Marines were given a “constant emphasis” on drinking water before and during the activity.

Drinking too much water is dangerous because the body cannot excrete that much fluid. Excess water then goes to the bowel, which pulls salt into it from the body, diluting the concentration of salt in the tissues.

Changing the concentration of salt, in turn, causes a shifting of fluids within the body, which can then induce a swelling in the brain. The swollen organ will then press against the bones of the skull, and become damaged.

Previous cases of water toxicity have been noted in athletes who consume excessive amounts in order to avoid heat stroke. In addition, certain psychiatric patients may drink too much water in an attempt to wash away their sins, or flush out poisons they believe have entered their bodies.

In 1998, the Army released fluid replacement guidelines, which recommend a certain intake of water but limit it to 1 to 1-1/2 quarts per hour and 12 quarts per day.

Military Medicine May 2002;167:432-434



Although water is the best liquid you can drink, and I recommend drinking only water, you can overdo it. There is a difference between optimizing and overdoing. As this study shows, drinking too much water can decrease the sodium in your blood to extremely dangerous levels.


As I have told my patients over and over, whether a world class athlete or a week-end athlete, sip small amounts water… one mouthful (2 to 3 ounces) every 30 minutes while awake for the rest of your life. If you are exercising and/or perspiring then sip a mouthful of water every 15 minutes. Dinking large amounts of water at one time can also disturb the BUN-CREATININE ratio in the blood and cause dehydration and all the attendant problems such as cramping, etc.