8 Ways to Purify Drinking Water

Introduction

Amongst all the necessities for survival, purified drinking water is one of the most critical. You can only survive about three days without water, less if you are trying to survive in a hot climate. That makes water a very high priority.

When we’re talking about pure water, that’s not the same as clean water. You can find a lot of clean water around that’s not pure. The cleanliness of water usually refers to how clear it is. But when we’re talking about purified water, we’re talking about water that doesn’t have anything living in it.

Bacteria, protozoa and other microorganisms can cause serious health problems. Drinking impure water can literally be deadly. While drinking water that isn’t properly purified will usually only cause diarrhea and vomiting, even that can be enough to kill you if you get dehydrated. In a survival situation, all water is suspect; it must be properly purified to ensure that it doesn’t have any of those little critters living in it.

There are many ways to purify water. The majority of them break down into two basic categories: mechanical filtration and chemical purification. Both are effective for making sure that your drinking water is safe for you.

The Details

  • Water Filters. Mechanical filters are probably the most common form of water purification used. Not only can they clean out any microorganisms, but they can also get rid of all the sediment that makes the water cloudy. However, for a mechanical filter to truly provide you with protection from bacteria, it needs to filter down to 2 microns. To filter out viruses as well, it needs to filter down to 0.2 microns. Most mechanical filters can’t filter that fine.

There are a couple of companies that manufacture high quality filters which are back-flushable. That means that clean water can be run backwards through the filter, under pressure, to clean the filter out. These types of filters can be use to filter as much as a million gallons of water before they need to be replaced. While expensive, in a survival situation they are priceless.

  • Chlorination. Chlorine is one of the most common ways around of purifying water. This is commonly used in city water systems and swimming pools alike. Chlorine is uniformly fatal to bacteria, making the water clean. You can easily find chlorine in the grocery store, sold as common household bleach. Don’t get the “color safe” bleach or the scented kinds, just common bleach. Eight drops is enough to purify one gallon. Leave it sit for about a half-hour after adding the bleach to give it enough time to act.
  • Iodine. Tincture of iodine works the same as bleach, except you need to use a little more of it. This is usually 2% iodine, along with 47% alcohol. You need to add a minimum of 20 drops to every gallon of water. If the water is cloudy, you might want to add more, up to double that amount. This is a common method of water purification in many third-world countries.
  • Boiling. This is one of the most commonly known methods of purifying water. While effective in killing all microorganisms, heating water to a boil requires a lot of fuel. The water must come to a full boil and stay there for five minutes. Unless you are going to make coffee out of the water or use it for cooking, you’ll probably want to allow it to cool before drinking it.
  • Pasteurization. It isn’t necessary to boil the water to kill the microorganisms in it; all you need is to get the water up to 158°F (70°C). This is called pasteurization, after Louis Pasteur, a 19th century chemist and microbiologist who discovered the need of purifying drinking water and developed this method for doing so.

If you don’t have a thermometer with you, it can be a little difficult to know when your water has reached the necessary temperature to ensure its safety for drinking. There is a wonderful device, called the WAPI (Water Pasteurization Indicator), designed for use in third-world countries to solve that problem. The WAPI is a plastic capsule that has a wax pellet in it. All that needs to be done is to float the WAPI in the water as it is being heated. When the wax pellet melts, the water is pasteurized.

  • Distillation. Of all the survival methods of water purification, distillation provides the surest way of gaining clean, pure water. However, it is also the hardest to do. To distill water, you need an enclosed vessel to heat the water in. The steam coming off the water is then captured and passed through a cooler to condense it back into water. A coiled copper line is typically used as a condenser. As long as the coil goes downhill all the way, the water will drip down, coming out pure.
  • A Bio-Filter. Besides commercially available filters, it is possible to make an excellent water filter out of commonly available materials. This type of filter, called a bio-filter, will remove 99% of the bacteria in the water, as well as many chemicals. The bio-filter can be made in any container, like a five-gallon bucket.

The bio-filter is made in three layers: gravel on top, sand next, and activated charcoal or activated carbon on the bottom. The water is poured in from the top and allowed to percolate through the layers, coming out purified at the bottom. Each successive layer removes more impurities.

When a bio-filter is first made, the water coming out of it will be muddy with black flecks. This will clear up after several gallons of water are run through it. This cleaning cycle can be reduced by thoroughly rinsing the ingredients before building the filter.

  • Chemical Filtration Tablets. Several companies make chemical purification tablets. The most common of these uses the chemical halogen. While effective, the tablets leave a bad taste in the water. They are also only effective as long as your supply of tablets lasts.

The Bottom Line

While there are a large number of ways of purifying water, they aren’t all uniformly effective. Some are better suited for use at home, while others would be more effective in the wilderness. Since purified water is such an important part of survival, it is highly recommended that you have more than one method available, both in your at-home survival supply kit and in your bug-out bag.