“How long should you boil water to make it safe to drink?”
When I ask this question to small groups, I usually get a lot of different answers. They range from 1 minute to 30 minutes. Thirty minutes is a long time! In fact, a lot of the water would be lost to steam if you boiled it for 30 minutes. You’d have create a primitive way to capture that steam, allow it to cool, and then collect the water as it condensed back to liquid form.
Fortunately, 30 minutes of rigorous boiling is not required to kill pathogens.
When you are in survival mode, whether simply lost in the woods during a weekend campout or after a major natural disaster such as a regional flood, it’s critical to stay hydrated. Next to air and shelter, water is the next most important item to seek out.
Under stressful conditions, going just a couple of days with too little water can be debilitating and even life threatening. It’s important to stay hydrated and watch out for the signs of dehydration.
However, you don’t want to risk making matters worse by drinking water that may be contaminated with pathogens such as giardia or cryptosporidium. They can cause diarrhea, gastrointestinal discomfort, and other issues that will make survival extremely tough.
You must purify the water before drinking it. Even clear, fast moving water can carry microscopic organisms that will wreak havoc on your digestive system.
There are many ways to make water safe to drink. Chemicals such as iodine and chlorine can be used to kill unwanted microorganisms. Ultraviolet light can also be used to retard their ability to reproduce, making it safe to consume infested water. You can also use a filter to remove the disease causing parasites.
All of these have their place in survival. However, they are typically dependent on a non-renewable source. You can run out of chemicals. You will run out of batteries for the ultraviolet Steripen. Filters will get old and will need to be replaced.
Fire, on the other hand, is renewable. As long as you can make a fire, even by rubbing two sticks together, you can have fire. And if you have fire and a container to put water in, you can purify water.
According to the EPA, waterborne illnesses can be prevented by bringing water to a boil for 1 minute. Water boils at 100C or 212F. Typically, most pathogens are dead before the water even begins to boil. 185F will kill most microorganism in just a few minutes.
If you are familiar with the Ideal Gas Law, you know that temperature, volume, and heat are proportionally related. What does this mean to us? At higher elevations, there is less pressure so a longer heating time is required to achieve the same affect. A safe rule of thumb is at elevations greater than 5,000 feet, water should be brought to a boil for 3 minutes.