Can You Drink Too Much Water? What Everyone Should Know About Water Toxicity

by | Read time: 5 minutes

Staying hydrated is important to good health. But drinking too much water can have dangerous – and even deadly – consequences.

Recently, a 35-year-old woman in Indiana died after becoming overhydrated. Ashley Summers was dehydrated after a weekend of boating and tried to make up for it by quickly drinking large amounts of water, including four bottles in less than a half-hour.

The water was too much for her body, creating a condition known as water toxicity. As Summers’s brain tissue swelled, she fell unconscious and subsequently died.

The tragic and frightening story is a reminder that even when it comes to water — something essential to life — it is possible to get too much of a good thing.

Concept of Can You Drink Too Much Water Represented by Woman Taking a Break from Run in Park Drinking Bottle of Water

Why is too much water dangerous?

Consuming too much water too fast can be dangerous in several ways.

Overhydration can dilute blood electrolyte levels, impacting heart and organ function, says Nancy Farrell Allen — a Fredericksburg, Virginia-based registered dietitian nutritionist, and founder of Farrell Dietitian Services

“Excess water can also displace nutrients received from other foods and beverages,” says Farrell Allen, who is also a spokesperson for the Academy of Nutrition and Dietetics. Drinking too much water also puts a demand on kidney filtration and bladder control, she notes.

When you consume too much water too fast, it can cause sodium levels to fall dangerously, a condition known as hyponatremia. Sodium is crucial to keeping a proper balance of fluids inside and outside cells.

As sodium levels decrease, water rushes into your cells, causing them to swell. In your brain, this can lead to pressure that triggers symptoms such as:

  • Confusion
  • Drowsiness
  • Headaches

A spike in blood pressure and a lower heart rate (bradycardia) can follow.

Eventually, the situation can become so dire that you can have seizures or fall into a coma. In a worst-case scenario, death can follow.

Who is at risk of drinking too much water?

Endurance athletes are among those at greatest risk, because they are in danger of consuming too much water without properly replacing electrolytes such as sodium.

A study of runners in the 2002 Boston Marathon found that 13% had symptoms of hyponatremia, and 0.6% were in a critical phase of the condition.

Other research has found that members of the military also are at higher risk of drinking too much water during training and thereby falling prey to water toxicity.

Some people drink water compulsively, a condition known as psychogenic polydipsia. This can put them at risk of consuming dangerously high levels of water during a short period.

However, as the tragic story of Ashley Summers shows, anyone can develop life-threatening water toxicity if they are not careful.

How to drink water safely

The key to staying hydrated and doing so safely is to consume water slowly and regularly throughout the day.

“Do not drink water rapidly,” Farrell Allen says. “Consume that content over an extended period of time.”

Most experts suggest that you drink about eight 8-ounce cups of water every day, Farrell Allen says.

“Another rule of thumb is to consume half your body weight in ounces,” she says. That means a man who weighs 150 pounds would try to drink 75 ounces of water each day.

One way to make sure you get enough water — and not too much — is to put yourself on a hydration schedule. Farrell Allen has her patients divide their daily water intake into three timed periods:

  • 6 a.m. to 11 a.m.
  • 11 a.m. to 3 p.m.
  • 3 p.m. to 7 p.m.

Adhering to that schedule and only drinking your allotted portion during these periods prevents people from drinking water too rapidly and encourages them to hydrate over an extended period. “Give your body time to process it slowly,” Farrell Allen says.

The Centers for Disease Control and Prevention says you should not drink more than 48 ounces of fluids — about 1.5 quarts — in an hour. This includes water, sports drinks, energy drinks and other beverages.

Your kidneys can remove a lot of water from your body each day – up to 20 to 28 liters. However, they cannot excrete more than 1 liter in a hour. This is why drinking a lot of water rapidly can be so dangerous.

Staying hydrated

Of course, for most of us, being dehydrated is a much bigger threat than taking in too much water.

Drinking water consistently throughout the day is a key to avoiding dehydration. “You want to drink water before feeling thirsty,” Farrell Allen says, noting that thirst itself is a sign that you are becoming dehydrated.

Also, keep an eye on the toilet bowl. “Urine should be colorless or pale yellow,” Farrell Allen says. “Dark urine may signal an insufficient water intake.”

Take a proactive approach to staying hydrated. Farrell Allen suggests planning ahead if you are on the go by using a portable cooler or insulated cup tumbler to make sure beverages — water, milk or juices — are available.

You can also include food items that contain a good water content, such as watermelon, tomatoes and other fruits.

“Take water breaks in hot weather — even in an ice rink if exercising heavily,” she says.

She also suggests that after consuming potentially dehydrating diuretic beverages — including caffeine beverages such as coffee, tea and energy drinks – you follow them up with a glass of water. Finally, consume electrolyte- and carbohydrate-rich beverages any time you exercise for at least 60 minutes.

“These all help to space out your water consumption,” Farrell Allen says.

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