Basic Survival Needs: What Do You Need to Survive?

The so-called rule of 3’s is a pretty standard idea in the survival community. It states that a human can live for three minutes without air, three hours without shelter, three days without water, and three weeks without food. It’s not exactly scientific, but it’s a good way to remember how long a person can go without certain things in a survival situation.

The basic survival needs for a human are oxygen, shelter, water, food, and sleep. Sleep is often ignored, but it’s required to keep the brain functioning properly and a lack of sleep will eventually lead to you not being able to supply yourself with the other 4 basic needs.

Let’s look at each of these basic survival needs a little closer.

Five Basic Survival Needs

Your basic survival needs are those things that you absolutely need to have in order to survive. Oxygen, shelter, water, food, and sleep are all necessary.


We need oxygen to survive. Our bodies are designed to breath normal air which is about 20.9%. Occupational Safety and Health Administration (OSHA) has determined that safe oxygen concentrations for humans are between 19.5 and 22% oxygen.

If you’re in an environment that less than 19.5% oxygen, it’s considered to be oxygen deficient. Environments that have more than 22% oxygen are considered to be oxygen-enriched and start to become hazardous as well. Luckily, you’re not likely to encounter either of these unless you work around confined spaces or decide to use a confined space as shelter.


Hypoxia is the name of the condition that happens when the tissue in your body isn’t getting enough oxygen. This can cause damage to the brain and liver in just a couple of minutes.

Most of us don’t need to worry about it, but if you or your family members have asthma or other breathing problems, you should know what to look for.

Common hypoxia symptoms:

  • Changes in the color of your skin
  • Confusion
  • Cough
  • Fast heart rate
  • Rapid breathing
  • Shortness of breath
  • Slow heart rate
  • Sweating
  • Wheezing

You could also find that you don’t have breathing problems under normal conditions, but if you get caught in a riot where tear gas or pepper spray are being used, you could also start to show hypoxia symptoms. Get to fresh air as soon as possible.

Gas masks protect you from things like riot control agents, but they don’t do anything in oxygen-deficient atmospheres!

Drowning is probably the first thing most of us think of when we think of not having oxygen. As the lungs fill with liquid, the body can’t get oxygen and then loses consciousness and eventually dies.

We can only go for 3 – 6 minutes without oxygen. The time varies a little between people but even a couple of minutes without oxygen can cause permanent brain damage.


Shelter helps us regulate our internal body temperature. Shelter is anything from your clothing, to a survival shelter, to our homes. Some animals have heavy coats of fur to help them, we have our brains.

Dressing appropriately for the expected environment is the most basic form of shelter that we have.

In a survival situation, you should get out elements as soon as you can. Hot weather and cold weather are both possible causes of injuries when you’re just trying to make it one more day.

The exact temperature will dictate how quickly it can kill you, but even exposure to somewhat harsh environments without shelter can kill in a matter of hours.

Exposure to the Elements

Exposure to the elements is often one of the first things that cause death in survival situations. As our body temperature drops, we start to experience hypothermia and as it rises we start to experience hyperthermia.

Hypothermia is a medical emergency that happens when you lose heat faster than your body can produce it. Normal body temperature is around 98.6 F (37 C). Hypothermia happens as your body temperature falls below 95 F (35 C).

When your body temperature drops that low, your heart, nervous system, and other organs can’t work normally. If you don’t get treatment, hypothermia can eventually lead to complete failure of your heart and respiratory system and ultimately lead to death.

Hypothermia normally happens due to exposure to cold weather or falling into cold water. You treat hypothermia by warming the victim to raise their body heat.

Hyperthermia is when the body gains heat faster than it can cool itself. It becomes a medical emergency when the body gets to 104 F (40 C).

Heatstroke comes in two forms:

  • Nonexertional heatstroke. This type of heatstroke is caused by simply being in a hot environment which leads to a rise in core body temperature. Nonexertional heatstroke typically occurs after exposure to hot, humid weather, for prolonged periods. It is most common in those with illnesses or adults over 65.
  • Exertional heatstroke. This type of heatstroke is caused by an increase in core body temperature brought on by intense activity in hot weather. If you’re working in extreme heat can find themselves succumbing to exertional heatstroke. It’s most likely to occur if you’re not used to high temperatures.

You can take the following steps to reduce the person’s core temperature:

  • Get them to shade or air-conditioning: If you don’t have air conditioning keep them calm and lay them on their backs with their legs above their heart in the shade.
  • Cool off with damp sheets and a fan.
  • Take a cool shower or bath.
  • Rehydrate by drinking plenty of fluids.

The CDC found that cold weather killed nearly double the number of people that hot weather did.


Everyone knows how important water is to our survival. It’s one of the first things you should store when you start prepping and it’s one of the first things that you’ll need when you in a survival situation.

Based on research, the bare minimum that a human needs to survive is 1 liter a day, but experts suggest that you should be drinking 64 oz of water every day to maintain proper hydration. This amount increases if you live in extreme heat or cold and based on your activity level.

The body relies on water to do the following:

  • Regulating body temperature.
  • Removing waste from the system.
  • Cushion the brain, spinal cord, and joints.
  • Absorbing nutrients into the body.
  • Prevent certain medical conditions.

Losing water will cause the following to happen to the body:

  • Respiration will slow as the mucus in your lungs thickens.
  • The body will begin to overheat when there isn’t enough water to cool it through sweating.
  • The kidneys will have to work harder, eventually failing.
  • Loss of cognitive function will gradually increase stress levels and increase your heart rate.
  • The intestines will absorb as much water from your food as they can and lead to constipation.
% of Body Weight Lost in Water Symptoms
2% Thirst
3% Severe Thirst, Absent-Mindedness, Loss of Appetite
4% Flushed Skin, Irritability, Increased Body Temperature, Exhaustion, Decrease in Urine
5% Headache, Feverish Feeling
8-10% Swaying, Convulsions
over 20% Kidney Failure, Death


Food is arguably the least important part of our survival needs. It’s miserable to be hungry! Luckily, it takes quite a long time to actually die from starvation.

The British Medical Journal published a study that looked at hunger strikes that happened in modern times. The study showed that humans can last 21 – 40 days without food during these self-imposed periods of starvation. All of these hunger strikes ended because of the severe medical effects brought on from the lack of food.

In a survival situation, hunger is going to feel like it’s life-threatening pretty quick, but it won’t kill you for a long time. Most people can survive 45 – 60 days without food before dying, but they are basically rendered immobile and unable to care for themselves long before that.


I’m really surprised to see that most people don’t consider sleep to be a necessity for survival! After just a couple of days without sleep, you can lose a lot of your ability to reason and you may even start to hallucinate.

The longer you go without sleep, the less you’ll be able to think clearly and creatively. This can be a killer in a survival situation. A lack of sleep causes distraction, increases the risk of accidents, and decreases the effectiveness of the central nervous system, endocrine system, immune system, respiratory system, and digestive system.

Not sleeping also causes psychological risks that can be fatal when you’re trying to make it out of a horrible situation intact. The psychological risks of not sleeping include:

  • Impulsive behavior
  • Anxiety
  • Depression
  • Paranoia
  • Suicidal thoughts

The National Sleep Foundation did a study that examined how much sleep we actually need. This is how much sleep we need based on age:

  • Older adults, 65+ years: 7-8 hours
  • Adults, 26-64 years: 7-9 hours
  • Young adults, 18-25 years: 7-9 hours
  • Teenagers, 14-17 years: 8-10 hours
  • School-age children, 6-13 years: 9-11 hours
  • Preschool children, 3-5 years: 10-13 hours
  • Toddlers, 1-2 years: 11-14 hours
  • Infants, 4-11 months: 12-15 hours
  • Newborns, 0-3 months: 14-17 hours

Routinely getting less sleep than what’s listed can lead to chronic sleep deprivation which has its own risks.


We need oxygen, shelter, water, food, and sleep to survive. We see a lot of people discussing oxygen, shelter, water, and food all the time, but sleep is overlooked a lot more than it should be.