The Survival Rule of Three

Have you heard of the survival rule of three? Although it’s just a guide, this handy little rule has been around for a long time and can help save your life in extreme situations.

When you’re out in the wild, anything can, and unfortunately, does happen. So this is why we practice learning new skills and mastering old ones, so should anything actually happen, you’re better prepared for the real survival situations. So what happens if you do find yourself in an extreme survival situation? How long can you last? The rule of 3 helps us understand how long we potentially have before we could potentially meet the end of the line, and each one works as part of the previous; so for example, you could survive 3 hours in a harsh environment without shelter, and you could survive 3 days without water but only if you have shelter to protect from the harsh environment, and so on.

So what are the survival rules of three?

3 Minutes Without Air

You can survive 3 minutes without air (or from severe blood loss) Without oxygen your brain cells start to die, and prolonged periods of oxygen starvation can lead permanent damage. It is believed that we can last a bit longer than 3 minutes, but by this point the damage caused would be very severe.

The brain represents just 2% of body weight, yet it uses about 20% of the body’s oxygen supply. Without it, the brain can’t perform even the most basic functions. The brain relies on glucose to power neurons that control everything from conscious functions like planning and thought to automatic unconscious processes like heart rate and digestion.

Without oxygen, the brain’s cells cannot metabolize glucose, and therefore cannot convert glucose into energy.

When your brain is deprived of oxygen, then, the ultimate cause of brain death is inadequate energy to power the brain’s cells (1)


3 Hours Without Shelter

So as long as you have air in your lungs, we move onto shelter. You can survive 3 hours without shelter in harsh environments and by harsh we mean extreme cold or extreme heat. You may think that it may never get that cold or that hot, even here in the UK, although our weather has a tendency to be a bit miserable most of the time, does it really get that harsh? When you’re up in the fells, or mountains of Scotland or Wales, it can get very cold, and as recently as 1995 in Scotland it recorded -27.2°.

The symptoms of hypothermia are violent shivering, disorientation, memory loss, slow or shallow breathing, slurred speech, drowsiness, exhaustion, or a weak pulse. (2)

Heat stroke is a life-threatening form of hyperthermia. It occurs when the body is overwhelmed by heat and unable to control its temperature. Heat stroke occurs when someone’s body temperature increases significantly (generally above 104 degrees Fahrenheit) and has symptoms such as mental status changes (like confusion or combativeness), strong rapid pulse, lack of sweating, dry flushed skin, faintness, staggering, or coma. (3)

3 Days Without Water

You have air in your lungs and a shelter, so how long can you survive now? 3 days; you can now survive 3 days without water. Water gives us life, it’s why we search for it on other planets as an indication that life could be ‘out there’, so it’s vital that we keep ourselves hydrated at all times. Even the slightest state of dehydration can have negative impacts on our body, causing fatigue and mood changes. Going 3 days without water can cause serious problems, including death. What’s worse is when you’re dehydrated, your blood thickens causing your heart to pump harder to push blood around your body, then with less water your body will struggle to regulate your body temperature, thus resulting in an increased chance of hyperthermia, which we know from above is something we want to steer clear of.

3 Weeks Without Food

So you have your air, your shelter and your water, but no food; Now you have about 3 weeks to survive. Now although this is a reasonably long time to be able to last, you certainly wouldn’t want to get anywhere near the max 3 weeks. In this time your body will begin to shut down and cause all sorts of problems for you. Without sufficient intake of carbohydrates and fats, your body struggles to process water intake as well, leading to dehydration. This is as well as blood sugar problems, blood pressure problems, electrolyte imbalances and mental side effects. You could experience a whole host of problems as a result, such as Edema, Blindness, Kidney Failure, Seizures, and heart attacks.


The survival rule of three



(1) Spinalcord.com

(2) CBS News

(3) NIH.Gov