How long can you live without water?

If you are healthy, you may survive without water from less than a day to up to 10 days, which depends mainly on how much you sweat ⁹.

People have survived for more than 6 weeks and some even for several months without food.

Survival Without Water In a Temperate Climate

In a temperate climate that is neither cold nor hot (temperature range 50-70 °F or 10-21 °C, which allows no or only minimal sweating), a healthy person may survive without water (and food) for up to 10 days ⁹.

According to online newspaper reports, people of different ages, from newborns to 80-year-old woman have survived for several days without water.

In y. 1985, a newborn boy has survived in an incubator for 235 hours or almost 10 days (from his 4th to 14th day) under the rails of 1985 Mexico earthquake ¹.
A seven-year-old boy and his 10-year-old sister have survived for 7 days under the rails of the 2010 Haiti earthquake, but one of their younger brothers has not ⁷.
In October 2004, in Redmond, Washington, United States, a 17-year-old girl was found trapped in the car after the accident, having survived for 8 days without water and food ⁵.
In January 2010, in the town of Sitges in Spain, a 35-year-old woman has survived for 8 days trapped in an elevator ⁸.
In December 1967, in Pittsburgh, Pennsylvania, United States, a 77-year-old woman has survived 7 days locked in the basement without water and food ³.
In January 2004, in the Iranian city of Bam, a 97-year-old woman was rescued from the ruins of the earthquake, having survived for 8 days without water and food ⁴.

Survival Without Water In a Hot Climate

While sitting in a shade ⁹:

at 120 °F (48.9 °C), you may live for 2 days without water
at 100 °F (37.8 °C) for 5 days
at 90 °F (32 °C) for 7 days.

Traveling in the desert at 104 °F (40 °C) daytime, ~68 °F (~20 °C) night time without water can limit your survival time to 16 hours ².

Frequently Asked Questions and Dehydration Facts

1. Does it make sense to drink a lot of water to increase your body water stores in preparation for the time when you expect to be without a water source?

When you are already well hydrated (you have your usual weight) and you continue to drink, you will excrete any excessive amount of water in the urine within few hours ². When you consume salt along with water, either by drinking sports drinks or by eating salty foods, or when you drink water with glycerol, the water will stay in your body for few additional hours, but not likely for more than 24 hours.

2. What would be a good drinking plan when you have a limited amount of water available?

Drink water when you are thirsty. Postponing drinking does not prolong your survival time ². Drink few sips of water at the time frequently rather than drink pints of water at once, because this stimulates excretion of water in the urine, even when you are dehydrated. You can have a goal to drink as much as needed to excrete plain yellow urine — not clear urine, because this may indicate excessive drinking and not brown because this speaks for severe dehydration.

When you are about to run out of the water, frequently drink in small sips rather than keep water beside you. Cold water helps to reduce your body temperature and thus reduce sweating. Drinking water does not stimulate sweating ².

When you are severely dehydrated, and you feel you might faint, and you have only small amount of water available, drink it all, because when you lose consciousness, you cannot drink.

3. Can you drink urine to postpone dehydration?

In a temperate climate (50-86 °F or 10-30 °C), many healthy people can survive 7-10 days without drinking any water. Drinking urine at this time would not significantly or at all prolong your survival time.

4. Is it safe to drink seawater?

Usually not, because, roughly, for each liter seawater drunk you have to excrete about 1.5 liters of urine to get rid of excessive salt, which results in about 0.5 net water loss for every liter of seawater drunk ^[10].

By drinking 1 liter of seawater, which contains about 3.5% of salt, you consume 1,200 milliosmoles (mOsm) of excessive salt, which needs to be excreted by the urine ^[10]. The kidneys are able to excrete about 1,200 mOsm of solutes per liter of urine but because they need to excrete about 600 mOsm per liter of urea and other products of metabolism, they can excrete only 600 mOsm of salt. The remaining 600 mOsm of salt from seawater will need additional 0.5 liter of urine in order to be excreted.

5. Can dehydration lead to hypovolemic shock?

Yes, severe dehydration can lead to heat stroke or hypovolemic shock.

References

How long can you survive without water?