In wilderness survival there’s an old maxim called the rule of threes. The rule of threes is there to remind you of the most immediate issue that must be solved first. It helps to focus on what is most essential and how long you will survive without it. So what is the rule of threes?
The first rule of three is that you can’t survive more than three minutes without oxygen or in icy water. While some free divers have been known to be able to survive up to 10 minutes holding their breath, most people cannot hold their breath for more than three minutes. Additionally, people who train for polar plunges can last typically longer than three minutes in icy water. However without training most people succumb to hypothermia cramping and start to drown from intense shivering after being in icy water for three minutes.
The second rule of three is that you can’t survive more than three hours without proper shelter in a harsh environment. A harsh environment would be one where hyperthermia can be induced. Additionally, any environment that is too wet or entirely too dry could be considered a harsh environment. Preventing hyperthermia is why hikers are told when going through the desert to take shelter during the day in the shade. It is also why we construct lean two shelters in temperate woods while camping at night. Although the human body is capable of self-regulating its temperature to some degree in extreme environments, the human body even in tip top shape, has difficulty keeping its temperature in its perfect range without some shelter in such environmental extremes.
The third rule of three is that the human body can only survive up to three days without water if sheltered from a harsh environment. Dehydration actually starts to set in within the first 24 hours. Dehydration can cause delirium, cramps, confusion, and lethargy. Dehydration can be lethal. That’s why it’s extremely important to find a source of water that is safe to draw from and purify as soon as possible when out in the wilderness. Most sources of water that are flowing with plants that are living by the edges or the banks are safe to purify or filter. Never drink unfiltered or unpurified or unboiled water in the wilderness.
There are multiple ways to make water safe for drinking out in the wilderness. You can boil it for a minute at sea level. You can use iodine tablets that are made specifically for purifying water. You can also purchase a water filter that can filter down to two microns. A very thorough way of making sure that you have clean water is to first filter it, then boil it, and then add purification tablets. Consuming unpurified water can lead to many different diseases such as travelers’ diarrhea, Giardia, and even hepatitis.
The final rule of three is that a human being can survive three weeks without food if you have water and shelter available to you. Now it has been proven that most Americans can survive a little bit longer than three weeks if they are healthy and have a little bit of fat on their body. The longest a human being has been recorded to have gone without food is a little over a year. This was done under medical supervision and primarily to lose weight for health reasons. No one should fast purposefully without medical supervision for more than 24 hours if at all possible. As a general rule however, human beings should not go without food for three weeks. There are multiple ways to find food in the wilderness. Human beings can fish and hunt, but one can also forage and gather nuts and seeds.