Rule of 3s Survival The Hierarchy of Needs Explained (edit)

Rule of 3 for Survival: The Hierarchy of Needs Explained

A life-changing crisis can happen anywhere, at any time, to anyone. Aside from carrying some supplies in anticipation of such events, a prepper’s knowledge is an essential resource that will increase their likelihood of survival.

The rule of 3s is a set of pointers that can be used as a guide to assess survivability and the course of actions that needs to be prioritized during a crisis. It defines how long an average person can survive without a certain resource, or how much time is needed to make a life-saving decision.

  • 3 seconds to react
  • 3 minutes without air (oxygen) or in icy water
  • 3 hours exposed to extreme weather conditions
  • 3 days without water
  • 3 weeks without food

The rule of 3s is arranged based on the priority of the needed task to accomplish during a crisis. How high a rule ranks in the list depicts the gravity of its importance. In general, failure to address a higher-ranking rule will result in a faster death.

There is no downside to learning the rule of 3s. It is easy to memorize, and extremely useful.

Hierarchy of Rule of 3s

3 Seconds to React

clock time

Perhaps the most important task to prevent injury, and leads to better survival is the recognition that something wrong is happening. A person in a life-threatening situation has 3 seconds to react or make a life-saving decision. Failure to do so will lead to missed opportunities.

For example, in the event of an earthquake, the tremor starts weak and then advances to stronger quakes. Through quick thinking and prior knowledge, one should already be on the move towards getting outside to open space, or under a sturdy table, once the quaking starts to get stronger. One must always stay calm and vigilant to be able to quickly assess the situation and react promptly.

3 Minutes Without Air

under water woman air

Among the organs, the brain is the most sensitive to oxygen deprivation and is the first organ to fail in an event that there is no access to air. Reversible brain damage can occur within 3 minutes of complete lack of oxygen. Longer than this results in irreversible brain damage, permanent disability, or death.

What this means is that any form of oxygen interruption to the brain will lead to injury. It can be caused by:

  1. Any injury that prevents a person from spontaneously breathing (airway obstruction, neck injury).
  2. Displacement of breathable oxygen in the environment such as in the case of carbon monoxide accumulation, or lack of breathable oxygen due to thick smoke in case of a fire.
  3. Massive blood loss reduces blood pressure, subsequently reducing the blood supply (and oxygen supply) to the brain.
  4. Hypothermia reduces blood flow to the brain or can stop the heart.

By identifying these causes, proper intervention can be duly applied in hopes of preventing permanent brain damage.

  1. Remove airway obstruction, and perform CPR.
  2. Leave the room, seek a well-ventilated area.
  3. Immediately stop the bleeding (apply a tourniquet or plug the source of bleed)
  4. Warm the person, or perform CPR.

3 Hours Exposed to Extreme Weather Conditions

extreme weather snow

Three hours is the critical time frame a person can survive when exposed to an extreme environment without an adequate form of protection. This rule applies to maintaining the body temperature at normal levels.

Low ambient temperature, moisture/rain, and wind increase the loss of body heat. At temperatures of 40 to 50 oF (4.5 to 10 oC) with light clothing and no shelter, an average person can die of hypothermia within 3 hours. Even worse, being submerged in a body of water at this temperature after going overboard puts you at a higher and quicker risk for hypothermia. Even at slightly higher than 50 oF, when the weather is wet and windy, or if submerged in 60°F (16°C) to 70°F (21°C) water, hypothermia can also set in (University of Michigan, Medicine Department).

Hypothermia is a body temperature below 95 oF (35 oC). This results in the slowing of the heart, and other metabolic processes which eventually leads to death.

Signs of Hypothermia

  • Shivering
  • Exhaustion
  • Confusion
  • Loss of dexterity
  • Memory loss
  • Slurred speech
  • Drowsiness
  • Temperature below 95 oF (35 oC)

On the flip side, exposure to a hot environment, and under direct sunlight without protection or water to drink leads to heat exhaustion, and heatstroke much faster.

Signs of Heat Exhaustion

  • Headache
  • Dizziness and confusion
  • General malaise (feeling discomfort, unwell, or ill)
  • Excessive sweating with pale and clammy skin
  • Rapid heart rate and breathing
  • Feeling of thirst
  • Temperature of > 4°F (38°C)

If the above conditions persist for more than 30minutes, heat exhaustion progresses to heatstroke and death.

3 Days without Liquid

drought weather

The human body consists of more than 60% water. All metabolic processes essential to life occurs in its presence. As such, an extreme loss, or gradual loss of fluid can eventually lead to death. In an ideal setting where a person stays put in a single location under the protection of a cover, it will take an average of 3 days for a person to die of dehydration.

However, physical activity and a warmer temperature escalate the water loss through sweating and increase in metabolic process. This results in faster consumption of water reserves, and a faster onset of dehydration and death.

Common Pitfalls that Lead to Faster Dehydration

Other sources will tell preppers that it is better to drink suspicious water than none at all. This is fatal advice and should never be followed. Ingestion of contaminants like chemicals, bacteria, viruses, and protozoa results in the hyperactivity of our bowel in an attempt to quickly get rid of these foreign bodies. As a result, fluid absorption is reduced, and fluid excretion through diarrhea is increased, leading to further dehydration.

As such, preppers should always make sure that the water being consumed is treated. There are various ways to purify water in an emergency setting that can take less than 24 hours. One of which is letting filtered (through clothes) water stand under the sun for a minimum of 6 hours. The UV radiation will kill most microorganisms, and reduces the potency of some chemicals.

Another pitfall that leads to faster dehydration is drinking seawater. When seawater is consumed, it raises the blood sodium level, which results in the transfer of fluid inside the cells, into the blood stream. The kidneys will then filter and excrete the excess sodium through urination. However, since the fluid was pulled out from the cells and organs, the person will urinate more fluid than what he drank, worsening the dehydration, and is potentially fatal.

3 Weeks Without Food

bread food

Our bodies are designed to handle short periods of food deprivation. An average person can live without food for up to 3 weeks or more. As long as there is water intake, our body has ways to produce its energy by breaking down muscles and fats. On top of this, several metabolic processes that are not essential to life are either slowed down or completely halted. This process reduces the daily caloric requirement of the body.

Without food intake, our body first consumes the energy reserves in the liver. This usually lasts for 2 to 3 days. If the liver reserves have been depleted, the next source of energy is fats. The energy from fats can last for more than a week until it gets depleted, and the body starts breaking down the muscles.

Fats in general give more energy when broken down. This is why people with more fat reserves can withstand starvation longer, than muscular people with very low body fat.

As starvation ensues, and muscles are broken down, the body can no longer support the metabolic processes needed for life. The diaphragm, a muscle responsible for breathing will eventually fail, resulting in suffocation and death.

The rule of 3s is not absolute. There are various factors like clothing, the physical condition of the person, the climate, and a person’s weight that affect the timing (the 3s) of these rules. Despite this, it is an invaluable guide in prioritizing the actions needed to be taken to increase one’s chance of survival.


Chris Green

Chris has always had an adventurous soul, and his love for the outdoors eventually led him to become a professional life skills advisor. He explains a multitude of different topics ranging from disaster preparedness and wilderness survival to self-sufficiency.

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