Camping & Survival

Water Purification

The EPA reports that 90% of the world’s fresh water supply is contaminated. According to the World Health Organization, 80% of all travel diseases are caused from contaminated water. Tap water, surface water (surface water is any standing or flowing body of water.), ice cubes and even bottled water can all harbor unsafe bacteria, viruses, protozoans and agricultural chemicals. By consuming even the smallest drop of contaminated water, you can get Hepatitis A, E-coli, salmonella, cholera and many other diseases and sicknesses. Most water contaminates come from human and animal waste. They are spread by rain and run-off in surface water.

During a natural disaster, tap water may become undrinkable, and when out backpacking, camping or hiking, it would be unwise to trust any water you come across, even if it looks crystal clear. Water purification will filter out chemicals, contaminants and pollutants from a water source, thus allowing you to drink the water that you find.

There are a number of ways you can purify and sanitize your water. Boiling removes micro-organisms, but chemicals will remain in the water. If you are at sea level, boil water for 5 minutes. If you are at 4,000 meters above sea level, you must boil your water for 20 minutes to remove the bacteria. Remember that even the clearest water, such as in a mountain stream, can still hold bacteria, viruses and chemicals. Traces of agricultural chemical have even been found in mountain streams.

Sanitizing water with the use of chemicals removes micro-organisms. Our cities’ water supplies are sanitized using chemicals and mineral additives. Chemicals work best in clearer water. Typical chemicals used are chlorine gas, chlorine, chlorine dioxide, iodine, ozone, and silver. Ultraviolet light is used in a final stage to ensure that any microorganisms which survive the chemical process are killed. Household bleach in proper amounts can even be used to sanitize water at home. Chlorine is the most used chemical to get rid of water pollutants. Sanitizing can also come in the form of chlorine dioxide tablets, which actually use oxygen, not chlorine, to clean water and is effective against viruses, bacteria, Giardia and Cryptosporidium. One tablet will purify one quart of water. Aquamira also has a water purification tablet. One tablet will treat one liter of water. It also uses chlorine dioxide. These tablets are good for light hiking, hunting, fishing, emergency kits, foreign travel and backcountry adventures.

Filtration systems use ceramics, membranes, glass fibers and/or plastics to filter water. The filters are based on pore size which is the opening size of the holes in the filter. When looking to purchase a microfiltiration system, look for ones that have a rating of 0.3 microns or lower or which use a reverse osmosis membrane system.

Activated carbon or activated charcoal is a very porous substance. In the water-filtration process, the fine granules absorb contaminants and pollutants. Activated carbon/charcoal is tasteless, odorless and non-toxic. The Frontier Filter from Aquamira is a necessity for your emergency and bug-out packs. This filter allows you to drink through a straw directly from the water source. It uses activated carbon and a filter and removes 99.9% of Cryptosporidium and Giardia bacteria such as E-coli. It will filter up to 20 gallons of water before you need to replace it.

When picking water to purify, it is best to choose flowing water as opposed to standing/stagnant water. If you can find a water source that is odorless, clearer, rather than cloudy, and has little floating debris in it, that should be your first choice. But you can still use water that is none of these, and sometimes you will not have a choice. If water is really dirty, let it settle in a big pot or bowl first or use a bandana, cloth or coffee filter to pre-filter out large pieces of sediment. When purifying water, it is best to use a combination of a filter method and a purification tablet.

We all know that traveling overseas can strike us with a case of Montezuma’s Revenge, but even clear, colorless and odorless water can harbor pollutants. Most of us trust our city’s tap water, but natural disasters such as floods, tornados, land slides and other disasters can taint city water. Whether you are traveling, hiking, camping or preparing your emergency pack, purifying water should be one of your first priorities.

The Mission of Cheaper Than Dirt!'s blog, The Shooter's Log, is to provide information—not opinions—to our customers and the shooting community. We want you, our readers, to be able to make informed decisions. The information provided here does not represent the views of Cheaper Than Dirt!

Comments (7)

  1. It has been shown that water pasteurizes at a much lower temperature than boiling. In the right conditions, you can even do it with just sunlight. The guys at have a device to help you do that. If you don’t have a good temperature indicator, just getting water hot enough to begin boiling is more than hot enough to kill any bugs in it, and that will save a massive amount of fuel for you.

  2. Actually, you don’t need to boil water anywhere near as long as you say. I did a bit of a write-up on it on my blog (shameless plug here)

    Basically, even if you’re at a high elevation as long as it boils you’re done. No need to boil it for extended periods of time. The blog post even has a link to the EPA web site with basically the same thing.

    If you’re in a situation where you need to be boiling your water, you are probably running on a very limited supply of fuel with which to boil it. Save your fuel, you might need it later.

  3. I thought about this once a while back… if there were a situation where I need to purify my own water at home, I’m fortunate enough to have a large canning pressure cooker. I should be able to kill just about anything much faster than regular boiling and in large batches at that. Typically a pressure cooker will operate at or above 240 degrees…

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