How much water should you drink a day?

Water makes up more than 60% of the human body and is essential to all life and bodily functions. If you're not sufficiently hydrated, you can experience detrimental health effects, including dehydration, which is a leading cause of preventable hospitalizations.

According to Colleen Muñoz, director of the hydration health center at the University of Hartford, chronic low water intake is associated with an increased risk of recurrent urinary tract infections, kidney stones, and some types of kidney disease. It can also increase the risk of type 2 diabetes, heart disease, and dementia.

Currently, the National Academy of Medicine (NAM) recommends men get a total daily fluid intake of 3.7 liters and women get a total daily fluid intake of 2.7 liters. After accounting for roughly 20% of fluids from food, the general recommendation is three liters (101 ounces) for men and two liters (68 ounces) for women.

However, NAM's recommendations are based on population-level data, so a person's individual hydration needs may vary depending on several different factors. Aside from body size and gender, activity level can have a significant impact on hydration needs. Someone who is training for a marathon will need to drink more fluids than someone who is mostly sedentary.

"The amount varies markedly on individuals based on weight, sweat rates, and ambient temperatures,” says Joseph Verbalis, chief of endocrinology and metabolism at Georgetown University.

How to stay hydrated

Instead of trying to stay hydrated from water alone, you can also drink other types of liquids, including coffee and tea.

"There's this myth that coffee is a diuretic and is going to dehydrate you, it's not true," says Juli MacKenna, manager of clinical nutrition at Tufts Medicine MelroseWakefield Hospital. "It makes you pee a little bit more, but coffee counts."

Separately, Dana Cohen, an integrative medicine practitioner, noted that coffee drinking is only a problem in excess. "Anything over four cups of coffee, and it starts to become a diuretic," she said.

Other drinks like milk, juice, sparkling water, and even soda can be appropriate beverages for hydration. However, it's best if your primary source of daily fluids is water to avoid unnecessary calories or sugar.

Some other tips to stay hydrated include adding flavor to your water to make it easier to drink, finding a water temperature that is most comfortable for you to drink, and getting water through food like fruits. If you're concerned about not drinking enough fluids, you can keep a water bottle in every room or set alarms to remind yourself to drink.

In general, if you drink water or other fluids with your meals and when you're thirsty, you will likely be able to stay well hydrated.

"Our kidneys are really, really good at holding on to water when we need it and excreting it when we have too much," says Derek Daniels, a professor of biological sciences at the University at Buffalo.

Overall, "hydration is important, but you don't need to turn drinking water into a full-time job," Reddy writes. "In other words, you can safely leave the 40-ounce tumbler at home."