“There are certain things that can make someone more at risk for it, but the overall thing that happens is that you have too much water and not enough sodium in your body,” Dr. Blake Froberg, a toxicologist with IU Health, told WRTV.

Here’s how to stay safe while ensuring you remain hydrated in the summer heat.

What is water toxicity?

Water toxicity is rare, but can occur especially on hot summer days. Overhydration can lead to low levels of sodium in the blood, which can be life-threatening, according to Julia Zumpano, a registered dietician at Cleveland Clinic’s Center for Human Nutrition. While staying hydrated is important, overhydration can lead to an overload for your kidneys. 

Exactly how much is too much depends on a variety of factors, including weight, age, location, overall health, and whether or not you are pregnant, but as a rule of thumb the Centers for Disease Control and Prevention recommends not drinking more than 48 ounces of water per hour.

What are some symptoms of water toxicity?

According to the Cleveland Clinic, symptoms of water toxicity, also known as fatal water intoxication, include:

• Muscle cramps or weakness
• Nausea and vomiting
• Lethargy, or low energy
• Headache
• Mental status changes

People with underlying medical conditions, as well as extremely active people, such as athletes, are at risk for water toxicity “as they tend to drink large amounts of water, while simultaneously losing sodium through their sweat,” according to the Harvard School of Public Health. “Women and children are also more susceptible to hyponatremia because of their smaller body size.”

Overconsumption of water due to exercise can also lead to water toxicity. Last month, TikToker Michelle Fairburn was hospitalized due to severe sodium deficiency after drinking an “excessive amount of water” as part of the popular 75 Hard Challenge, which includes following a strict diet; completing two 45-minute workouts (one of which must be done outside); drinking one gallon of water; reading 10 pages of a book; and taking a progress picture each day.

If you’re going to exercise and/or be in the heat for an extended period of time, experts recommend incorporating drinks with electrolytes, sodium, and some potassium.

How much water should you drink per day?

While the gold standard for many years has been the 8×8 rule, or eight glasses of eight ounces of water per day, the National Academy of Medicine suggests adequate fluid intake is about 125 ounces for men and about 91 ounces for women.

This includes total fluids from fruits and vegetables, water, and other beverages besides water, such as herbal tea, milk, milk alternatives, and smoothies; however, surgery drinks and soda should be avoided.

“Foods and beverages with caffeine can dehydrate the body, but they do not need to necessarily be avoided if adequate amounts of non-caffeinated beverages are consumed,” says Zumpano.

How to stay hydrated

If you struggle with getting enough water per day, you can try water bottles and/or apps that help track your water intake. Eating fruits and vegetables, such as tomatoes, watermelon, grapes, and pineapples, can also increase your water intake. 

You could experiment with adding flavor, such as lemon, lime, mint, or cucumber to enhance the taste of your water and encourage drinking. Experts also recommend setting timers to remind yourself to drink water at pivotal times, such as a glass before and after each meal.

“Most people do best sipping water throughout the day, but larger amounts may need to be consumed in hot temperatures, when sweating, such as in a sauna or during exercise, or if you are craving water—listen to your body,” says Zumpano. But don’t overdo it.