Survival Priorities And The Rule Of Threes


This may seem overly simplistic, but if any of us are going to survive, we must have a basic knowledge of what we need to do in order to survive. That means having an understanding of what will kill us (if we don’t take care of it).

In order to survive, we must understand what our survival priorities are. By that, we need to know which things are necessary in order to survive and understand their relative importance to each other. If any of us are ever caught in a do-or-die survival situation and spend all our time on things which are not critical to our survival – well, the chances are we won’t survive.


The top survival priorities using what is known as the Rule of 3s. It says, you can live: 3 minutes without oxygen, 30 minutes without maintaining your body temperature, 3 days without water, 30 days without food.

Keep in mind that those numbers are not absolutes. A lot depends on the individual’s physical condition and health, as well as environmental conditions. You may not be able to survive as long as three days without water if you are in a hot climate, where your body is losing a lot of water through perspiration. The point is that even though these are not absolutes, they are a good guide because they demonstrate to us the relative difference between the highest survival priorities.

So where does “food, clothing and shelter” fit into all this? Food is on the list, so we know where that comes in; but what about clothing and shelter? Those are both part of the same survival priority; they are used to help us maintain our body temperature, specifically to help us keep from losing core body heat.


We get oxygen from the air that we breathe. Putting it in a simplistic way, every time we inhale, the lungs remove oxygen from the air we’ve breathed in and replace it with carbon dioxide, which we exhale. The human body then uses oxygen for a variety of things. Of those, the brain is the largest user of oxygen. While the brain stores a supply of oxygen, that’s only enough to last for a few minutes. After that irreversible brain damage occurs.

Besides being underwater, we might find ourselves in situations where we are lacking oxygen (if we are caught in a fire or a gas leak). In both cases, other gases are being inhaled into our system, keeping our bloodstream from absorbing the oxygen we need. Other kinds of disasters like the aforementioned pandemic flu or chemical attack could lead to the air we breathe being compromised or unsafe. In these cases, while the air is still technically breathable, based on the survival priorities, our first goal should be to get our hands on a chemical/gas mask that can filter the air and make it safe to breathe.


Body Temperature

The human body is designed to operate within only a very small temperature range. If the core body temperature rises or falls only a few degrees, it’s enough to cause the person difficulty in thinking clearly and control their muscle movements. A few degrees more and it can kill.

The loss of core body temperature is more common and usually more serious than overheating, although both can kill you. Nevertheless, it is easier to lose body heat than gain it. Gaining body heat normally only happens through infections and disease. Yes, it is possible to gain body heat when doing physical activities in a hot ambient temperature, but the body has ways of shedding that heat, keeping it from becoming dangerous. Excess heat generally only occurs in very extreme situations. Excess body heat is called “hyperthermia.”

On the other hand, if the body is losing core heat, it can only do so much to produce more. It is not hard to reach a point where heat is leaving the body faster than it can produce that heat. That’s called “hypothermia.” It’s the biggest killer in the wild. Hypothermia most often occurs when someone gets wet and leaves their wet clothing on, rather than drying off and replacing it. Water is more conductive than air (25 times more conductive) – that’s why we feel extra cold in water even if it’s the same temperature as the air around us (and also why hot water feels ‘hotter’ than hot air of the same temperature).

Clean Water

When we refer to clean water in a survival sense, we’re referring to it being biologically clean. That means that there are no microscopic pathogens in the water (bacteria, viruses and protozoa). While there can be other dangerous things in the water (such as minerals and chemicals) these are the ones we are most likely to encounter, and they bring sickness along with them.

Because we can’t see these microscopic pathogens, it is necessary to assume all water is suspect in any survival situation. Before drinking it, it must be filtered or purified to remove the pathogens. While filtering is the most common method of making water safe to drink in a survival situation, not all water filters work that well. You want at least a 0.2 micron filter.

Water can also be purified by both chemical means and through heat. These will kill the pathogens, even though it doesn’t remove them, preventing them from having any effect on our bodies. That means that on top of water filters, water purification tablets and boiling water are also valid ways of making ‘wild’ water safer to drink.



Food is the lowest priority in the Rule of 3s; mostly because we can live off of stored energy in our bodies. While different experts will tell you different figures about how long a person can live without food (up as high as 100 days), the low end of that range is 30 days. Even if we can survive longer than that, our bodies will function much less efficiently after those first 30 days due to the lack of proper nutrition.

For short-term survival (less than 30 days), we are only concerned with the three macro-nutrients:

Carbohydrates – which break down in the body to form simple sugars, the energy source for our bodies
Fats – which break down slower into simple sugars, giving us long-term energy
Proteins – which are the basic building blocks for new cells. If we don’t eat proteins, our bodies will cannibalize themselves in order to make those new cells

As long as we are receiving those, our bodies can continue to function. But once we use up the stored micro-nutrients in our bodies, it begins to affect our health. As a general rule of thumb, once you go past 30 days, you need to add back in the micro-nutrients (which are mostly found in fruits and vegetables) in order to maintain your body’s health. Micro-nutrients are things like Vitamins, potassium, calcium and so forth.

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