A healthy person can survive without water from less than a day to up to ten days 9.
A Temperate Climate
In a temperate climate that is neither cold nor hot (50-70 °F or 10-21 °C; no sweating), a healthy person may survive without water (and food) for up to ten days 9.
- In y. 1985, a newborn boy has survived in an incubator for 235 hours or almost ten days (from his fourth to fourteenth day) under the rails of 1985 Mexico earthquake 1. Some other “miracle babies” rescued together with him were still alive as of February 2010 10.
- A seven year old boy and his ten year old sister have survived for seven 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 eight days without water and food 5.
- In January 2010, in the town of Sitges in Spain, a 35 year old woman has survived for eight days trapped in an elevator 8.
- In December 1967, in Pittsburgh, Pennsylvania, United States, a 77 year old woman has survived seven 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 earthquake, having survived for eight days without water and food 4.
A Hot Climate
While sitting in a shade 9:
- at 120 °F (48.9 °C), you may live for two days without water
- at 100 °F (37.8 °C) for five days
- at 90 °F (32 °C) for seven days.
Travelling 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 in order to increase your body water stores in preparation for 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 with the urine within few hours 2. When you consume salt along with water, either by drinking sport 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 with 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 overdrinking and not brown, because this speaks for severe dehydration.
When you are about to run out of water, drink frequently in small sips rather than keep water besides 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 in this time would not significantly or at all prolong your survival time.
4. Is it safe to drink seawater?
UsuaIly not, because, roughly, for each liter seawater drunk you have to excrete about 1.5 liters of urine in order to get rid of excessive salt, which results in about 0.5 net water loss for every liter of seawater drunk 11.