The Rule of Threes
There is a Rule of Threes that we use to begin teaching survival to kids. It states that you can live for about 3 minutes without oxygen, about 3 days without water, and about 3 weeks without food. That’s not saying you’ll be happy and healthy – it is sure to be a miserable existence, but you can live.
Using the Rule of Threes to inform our survival training suggests that finding food should be the least of our worries. These days it’s pretty hard to stay lost anywhere for three weeks – so don’t expend much time, energy, and thought on getting something to eat.
You do have to stay away from things that will deprive you of oxygen (known allergens, toxins, bears, etc…), but assuming you’ve stayed alive long enough to realize you’re lost and in a survival situation, you’re probably past the 3-minute mark.
How to purify water for drinking
This leaves water. You do absolutely have to figure out how to obtain drinkable water. Even if you can stay alive for around 3 days without water, half of that time you’re going to be useless from dehydration – so water should be one of your first considerations.
You can carry water with you, but water is heavy (8.3 pounds/gallon) and you’ll need a lot (at least 1 gallon per person per day) or more if you are exerting or it is hot.
You can make water safe to drink by boiling it for 3 minutes – but that means you have to have a vessel and the equipment or skills to build a fire.
You can filter water. There are a million kinds of filters on the market, each with their plusses and minuses.
There are even these cool gizmos called SteriPens that shine UV light into your water bottle to sterilize the germs in there so that they cannot multiply in your gut. These are neat but they are reliant on technology (batteries, functioning SteriPen) and they have been known to break in the middle of nowhere. Also, they are reliant on the clarity of the water – you have to be able to actually shine the light through the water, so if there are a lot of particles or mud in the water, UV might not do it for you.
An old, reliable favorite is the chlorine or iodine pills. These tiny pills release enough of their chemical agent to kill everything in your water bottle usually within about 30 minutes. I like these because they weigh nothing and are easy and reliable.
The Rule of Redundancy
The CDC recommends boiling for 3 minutes as the gold standard, or if that is not possible, any combination of 2 other methods – filter+chemical, filter+UV, UV+chemical. In my experience, any one of these seems to be sufficient, but the CDC guys are trying to be extra sure.
That reminds me of another guideline that we use when teaching survival skills – Two is one and one is none!
That means you want to have at least two ways to get every vital function done because one of them is sure to break or get lost (Murphy’s Law). So, if you bring two ways to get water, you’ll have one that works. But if you only bring one, you’ll break or lose it and have none.
That’s why it’s good to bring a full water bottle or two from home/camp, but also keep some chlorine pills or a filter with you when you venture out.