Although it depends on your age, activity level, and body demands, you may survive without water only for a few days. Hydration from water and food is essential for optimal body functioning and survival.

Proper hydration is essential to your survival. Your body needs to consume a significant amount of water each day to function properly. This is because you constantly excrete water through sweat and urination, so your body needs to replenish the lost fluids.

You won’t live long without consuming a healthy amount of water. It’s only possible to survive without water for a matter of days. Depending on certain factors, you may be susceptible to dehydration even sooner.

Research into how long humans can go without water is unethical, but press reports have recorded cases of people lasting 8 to 21 days without food or water. However, scientists believe the number, in most cases, is closer to about 3 days.

That’s because your body needs a certain amount of water to maintain essential health functions. The human adult body is about 70% to 75% water. It’s even higher in newborns and infants.

You can’t survive without enough water for very long, but the exact amount of time you can live without water varies. That’s because certain factors contribute to your body’s use of water, including your:

  • environmental conditions
  • activity level
  • age
  • health
  • weight
  • sex
  • food intake

For example, your body will sweat more in a hot climate, expelling more water. Your body will lose water more rapidly if you have a fever, diarrhea, or are vomiting. You’ll also use more water if you’re exercising.

People nearing the end of their lives who are using very little energy may live a few weeks without food and water, according to Canadian VirtualHospice.

Your body is highly attuned to the amount of water you consume. You likely get enough water in your body based on your sensation of thirst. If you drink when you’re thirsty, you’re likely getting enough water in your body on a daily basis.

Dehydration is the medical term for not having enough water in your body to function properly. Without enough water, systems in your body will change.

All the cells in your body require water. Without enough water, they shrink and begin to lose their function.

Your brain will signal your body to urinate less. This will occur through your kidneys. They rely on an adequate water intake to function properly.

Without enough water, the kidneys use more energy and wear on tissue. Your kidneys need to function adequately to flush out waste from your blood. Eventually, your kidneys will cease to function without adequate water intake.

Other organs and systems in your body will cease to function without water:

  • You may not be able to regulate your body temperature.
  • You may not be able to regulate your blood pressure.
  • You may develop an electrolyte imbalance.
  • Your joints may not work properly.
  • You may start to feel confused.
  • Your brain may swell.

Consuming other beverages

Water consumption also includes other beverages like herbal tea and juice. However, some beverages, such as those that contain caffeine or alcohol, can contribute to dehydration.

You don’t get hydration from water and other beverages alone. According to the Academy of Nutrition and Dietetics, food consumption contributes to about 20% of your daily water intake.

Some people may get even more water from their food if they eat a lot of fruits and vegetables, which contain a high amount of water.

Consuming foods high in water will help prevent dehydration. However, food alone isn’t likely to provide enough water to sustain you in the long term.

Water is much more essential to your body than food. People who engage in hunger strikes without food but with access to water can live two months or longer.

In a 2022 narrative study, healthcare professionals recommended that people engaging in a hunger strike drink 1.5 liters of fluids daily to maintain fluid levels. They also recommended 1.5 grams of salt to prevent electrolyte imbalances.

Experts differ on how much water humans need daily. This amount depends on age, weight, sex, and air temperature.

The daily recommended water intake from both beverages and food for adults ages 19 to 30 is 2.7 liters (91 ounces) for women and 3.7 liters (125 ounces) for men.

Some of the side effects and risks of dehydration include:

You must be careful with your fluid intake if you become dehydrated. The appropriate method of rehydration will vary from person to person.

Adults may just need to drink water to rehydrate. Small children may require an oral rehydration solution, which includes sodium in addition to water, to replenish the body appropriately. Children may need to take this solution in very small amounts at first.

If you’re severely dehydrated, intravenous administration of water and salt may be necessary.

Maintaining an adequate amount of water in your body is vitally important to your life. Without water, you’ll only be able to survive a few days.

Generally, your thirst will guide you when it comes to how much water you should drink. Keep in mind that exercise, hot temperatures, and illness may require you to increase your water intake to stay healthy. Contact a doctor if you suspect dehydration.