How Long Can You Survive Without Water?

[Nemesis]

(Ron Fontaine)

Importance of Adequate Water

When faced with a survival situation, clean drinkable water is often the most important consideration. People have survived without food for weeks or even months, but go without water for even just one day and the survivor will be in desperate straights indeed.

Knowing that water is by far the most important nutrient for the human body (besides oxygen) and, in particular, during a survival situation when finding potable water may not be easy, the question becomes – just how long can the human body survive without adequate water?

To maintain a high level of health and efficiency even in ideal environments, a minimum of two quarts of clean water per day per person is the generally accepted rule of thumb. In very hot or cold or very dry environments, or if you are physically active, two quarts of water a day may not be enough to sustain life over a period of days or weeks.

Water lost through sweating and normal respiration must be replaced in order to stay healthy and function at top efficiency. Water is also needed to process the food you eat, especially if it is salty or you eat heavy foods like meat.

Environment and Water Needs
In general the higher the temperature the greater your water consumption needs to be. If you are active or exposed to the hot rays of the sun you may need upwards of a gallon of water per day to stay to healthy.

Perhaps surprisingly, very cold environments can be as dry as the driest desert. This is because cold air cannot hold much moisture. This cold dry air serves to dehydrate your body with every breath you take. Cold dry air can also rob your body of moisture via loss from exposed skin. This is one reason why your lips may be prone to chapping. So during cold weather even though you may not be sweating nearly as much as when you are in a hot environment you may still easily become severely dehydrated without even realizing the danger you are in.

Wind can also play a role in the amount of water you need to take in. A dry wind on exposed flesh can suck the water right out of a person. Indeed, the remains of mummified animals and even people are often found in desert regions, their bodies totally dried out.

Effects of Going Without Water
Although two thirds of the human body by weight is composed of water, this water is needed for circulation and other bodily processes including respiration and converting food to energy. If you are losing more water than you are taking in, dehydration will occur.

It has been shown that if you lose just 2.5% of your body weight from water loss, you will loose 25% of your efficiency. For a 175 pound man that is only about two quarts of water. As the survivor dehydrates, his blood becomes thicker and loses volume. This causes the heart to work harder and circulation of blood to be less efficient. In a survival situation, loosing a full one quarter of your physical and mental abilities due to dehydration could mean the end of your life. Bottom line: drink plenty of fluids whether you feel thirsty or not so that you stay a peak efficency.

Survival Times without Water
Ill health, exposure to the elements, shock, and panic can reduce your survival time in any situation. An important additional consideration is whether or not to eat food when there may be an inadequate supply of water. Certainly foods that contain a high proportion of water, such many kinds of fuits and berries may actually aid the survivor in providing water. Meat, dry and salty foods should be avoided as they require water from your body for processing and will serve to dehydrate you further.

The survivor who is in good health, who uses his head, and rations whatever water is at hand may expect to be able to survive according to the following chart. Of course, there are many factors to be considered so your mileage may vary:




Recovering From Dehydration

The good news is you can lose as much as 10% of your body weight through dehydration and suffer no long term ill effects. Simply by drinking several quarts of water you will be restored in a very short time. However, a survivor who has lost this much water from his body will probably not be in a position to find water.

In cool temperatures, a loss of 25% of your body weight in water will probably be the end. If the temperature is over 90 degrees farhanheight then you may not make it even at the 15% dehydration level.

[Kenneth Eames]

Thank you for this. Your chart is very useful. It is an item that preppers need to consider. It could well be that many people will die because of the lack of this knowledge. Kenneth Eames.

[Skvez]

The table is a very vague guideline.
People ask me regularly "how much water do I need to bring" (on camping trips etc), the answer is that only they can answer that.
I've survived my whole life on less than 5 litres of water a day. I don't use (or appear to need) much. By contrast I've a friend who drinks easily three times what I do.

Everyone should spend one weekend measuring what they drink to get an idea of how much they typically use. It varies hugely person-to-person.

Also consider the arguments this is likely to cause if your group has to ration water. I may want to ration at 1 Litre a day while you feel this is killing you and you need 10 Litres a day, which I consider recklessly wasteful.

[Skean Dhude]

Like everything else this is just a guideline and when we look at guidelines we have to generalise. No option about it. Everything is average and everybody is unique. I, like Skvez, don't drink that much most days but some days I drink more just by reflex.

I always recommend testing your theories but in some cases, this is one, you don't want to try too much. Perhaps a good test would be to ration yourself to the guidelines and see how that goes. If you have some over great, if you are well short then you need to recalculate your water stores immediately.

[bigpaul]

common knowledge says: 3 DAYS without water, 3 WEEKS without food, 3 HOURS in either extreme heat or extreme cold.

[Nemesis]

This is extreme guide for survival it offers some information to get better understanding of how long you could expect to live in the shade doing nothing but trying to stay alive and hope you get rescued.

To ration water if it is something a group can’t agree on then you’re in the wrong group with a bad mind-set from the get go.

[bigpaul]

during WW2 the thinking was to ration water but i saw somewhere that rationing is not advised these days, i think it was Ray Mears or someone like that, who said if you've got water drink it, the thinking being you do more harm than good, to your internal organs, if you try to ration water.

[Nemesis]

(30 November 2011, 15:21)bigpaul Wrote: during WW2 the thinking was to ration water but i saw somewhere that rationing is not advised these days, i think it was Ray Mears or someone like that, who said if you've got water drink it, the thinking being you do more harm than good, to your internal organs, if you try to ration water.

Luckily for us BP we live in UK rain is our friend, as long as it is not radioactive. I farm rain because I know it is the best way to replenish my supplies in my area, my rain farm is running 660L constant and my stores far exceed that, a good group will ration and more so when the supplies going out are higher than the supplies coming in.

[bigpaul]

i live in a very mild part of the UK with above average rainfall, so no worries about water collection, i've got 6 large blue (ex farm) tubs waiting to have their lids removed to use as water butts.

[NorthernRaider]

Comment removed at authors request - Off topic