Even under favorable conditions, humans can only survive around five days without water. Alarming misdirections in the body occur after just a few hours. The brain suffers particularly quickly with fluid deprivation.
Drink water – your body will thank you
Sufficient drinking is essential for the body to function optimally. Günter Wagner, nutritionist and board member of the German Institute for Sports Nutrition, gives two to two and a half liters a day as a guideline for normal activity. If we absorb less fluid, the body works on a low flame.
The brain is particularly dependent on water: it consists of around 77 percent of the element. The liver, muscles and skin also have a fluid content of well over 60 percent. These organs are therefore particularly sensitive to a lack of water.
Circumstances of dehydration
When the body shows the first signs of dehydration depends on age, gender, activity and weight: the less a person weighs, the faster their body dries out. If the person moves more, he also loses more water through sweat. According to Wagner, active people, regardless of weight, consume around two and a half liters of fluid per day. A person weighing 70 kilos therefore loses about 0.2 liters of water per hour.
The deficiency initially affects the blood: it thickens, therefore flows more slowly and thus also transports oxygen and nutrients to the organs with a time delay.
Five hours without water: the effects
The first few hours of fluid deprivation include dry mouth and dry lips. After five hours at the latest, people begin to feel thirsty and uncomfortable. In addition, there are restrictions on movement: For example, those affected have to make greater efforts to perform a movement than with a well-hydrated body. In addition, body temperature and pulse increase because the thicker blood has to be pumped through the body with more effort.
The cognitive functions in particular deteriorate a few hours after the last drink: The concentration, ability to react and learn decreases. For example, the error rate when driving a car increases and it is more difficult to listen to a lecturer or conversation partner. The Rosbacher Drinking Study VI, in which Wagner participated, impressively demonstrated the importance of adequate hydration: “Drinking in the morning or during class alone improved the subjects’ IQ by five percentage points”.
The metabolism suffers from fluid deprivation
Ten hours after the last drink was consumed, there was further severe loss of performance: the concentration decreased even more, you became sleepy and impatient. In addition, the metabolism slows down – the added substances are therefore consumed more slowly.
If a person who weighs 70 kilos does not consume liquid for a whole day during normal exercise, this corresponds to a loss of water of around two and a half liters or four percent of their body weight. Significant circulatory problems, headaches and dizziness occur.
The consequences of two days without water
On the second day without water, sufferers experience the following symptoms:
- Shortness of breath
- problems walking
- tingling in the limbs
- Low to no saliva formation
- Difficulty speaking
- Strong decrease in mental performance
The symptoms become massive and the condition of the person more critical. After 48 hours, i.e. two complete days, a person weighing 70 kilos has a water deficit of around ten percent of their body weight.
Death threatens from day three
If the person does not drink drinks for more than two days, he falls into delirium and shows dramatic symptoms:
- Inability to swallow
- Problems hearing and seeing
- Dry and senseless skin
On the third day, the deficit was 11 to 20 percent based on body weight. With a water shortage of more than 20 percent, humans are no longer viable. Death from fluid deficiency is heralded by cramps, swollen tongue, and painful urination.
Incredible but true: A person survives 18 days without water
When water is removed, people usually die after five days. One who has endured much longer is the Austrian Andreas Mihavecz: he survived a whole 18 days with almost no fluids. Only the condensed water that he licked from the walls was available to him. In 1979, police officers mistakenly arrested him. They took him to a cell in the basement of the area and forgot him there. After 18 days, one of the officials found him because a strong stench had developed. Mihavecz was immediately transported to the hospital and nursed there again.
What you absolutely have to think about before your next outdoor trip.
So please do not forget to think of enough water for your next hike or camping.
If you are out and about in nature and have no access to fresh drinking water, we recommend that you take a mobile water treatment with you. Or you can boil the water that you have, for example from a river or a brook, over the fire to kill harmful bacteria.
Please don’t just drink the water from the river or a lake, our body is not used to dealing with the bacteria in this water. You would be very bad after a few hours or a day.
So before you go on an outdoor trip, think about how you can best supply yourself with water in the great outdoors. That is actually the most important thing about outdoor survival.