Survival Skills: How to Purify Water

Water is essential to human life. A person cannot go longer than three days without hydration. A person that does not receive liquid of some sort will, within three days exhibit signs of dehydration. Soon that person will die. Many people do not think about hydration on a daily basis. People get water from their food and juices, such as Gatorade and other drinks like colas and coffee. Safe drinking water for the most part, is taken for granted because in industrialized nations, there is not a lack of it. You must learn how to filter and purify water to keep yourself and family alive during a crisis, or when in a survival situation such as being lost or stranded in the wilderness.

Coliform Bacteria, Escherichia coli and Streptococci Are Common Bacteria Found In Water

The water that flows from any household tap is treated and purified to remove bacteria and metals such as lead. The water that is treated generally comes from reservoirs and lakes. The same water untreated can be found inrivers, lakes and ponds.

Filter Water before purifying

Ideally, you will have a way to filter the water. Charcoal and coffee filters are an excellent way to filter water. Have water filtering in mind when packing your survival backpack. Cloth such as a tee-shirt or piece of flannel or even cheesecloth can be used, as well.  A small stainless steel bowl is recommended. Charcoal placed in the coffee filter is the ideal filtering medium for water, it removes heavy metals and other contaminates. However, water filtered with charcoal will still need to be purified to ensure all the bacteria are destroyed. Activated charcoal can be purchased or charcoal as a filtering medium can be made from burning hardwoods.


  1. Make your own charcoal right in camp. Use only hardwoods such as maple, hickory or oak. Pull the wood from the fire when it looks like charcoal. If possible, cover the wood with ashes to smother the fire otherwise; it will simply burn to ashes. Use sand or soil if you do not have enough ash. Once cooled, rinse the ash or dirt off, crush the charcoal and fill a tin can with a coffee filter in the bottom, pouring the charcoal into the filter. Punch a small hole in the bottom of the can to allow the filtered water to drain into another container to be treated or boiled.
  2. Dip with one vessel and filter into another vessel such as an empty water bottle. The cup or bottle used to dip the contaminated water will have bacteria and contaminates at the drink line. Filter the water so the second container’s drink line is not contaminated.

Methods to Purify Water to Make It Safe for Human Consumption

  • Boiling (my preferred method)
  • 2% liquid iodine  (aka tincture of iodine)
  • Typical household 5% Chlorine Bleach Unscented

Water that is safe to drink is called potable water. You may see containers that state they are safe to store potable water or containers that state not to be used for potable water. Containers that are safe to store water in include a well-rinsed milk jug, bottled water containers, vinegar jugs and well-rinsed soda containers. Essentially any container that was used to package food items is considered food safe, and can be used generally to store or transport water.

It is recommended to treat as large a volume as possible at one time. Your water source may dry up, or you may have to vacate your camp in a hurry. Therefore, having purified water stockpiled allows you to travel with purified water.

How to Purify Water by Boiling

Prior to boiling, you should filter as much debris and sediment from the water as you can. You will need the means to start a fire and you must have a vessel in which to boil the water. The water must boil rapidly for at least one minute. Boiling water will cause a loss of water through evaporation, so boiling longer than one minute will cause you to lose water volume. Before drinking, you must let the water cool. Protect the water from contamination by any means possible. Boiled water will have a very bland taste. To enhance the flavor of boiled water or water treated with iodine or bleach, you can add tea plants as mint. Add the enhancements after the water has cooled.

Water that has been poisoned or contaminated with chemicals is not safe to drink even after boiling, treating with iodine or with chlorine bleach. If you suspect your water source is chemically contaminated you must find another source.

How to Filter and Purify Water Using 2% Liquid Iodine Using a Standard Eyedropper as a Measurement

Once again, the water must be filtered to remove sediment and other debris. The iodine will not work as well if the water is extremely cloudy from debris or sediment. The ratio is based on liters. The ratio for iodine is five drops per liter.  If after filtering, the water is still cloudy, you can double the ratio but do not add more than 10 drops per liter. Shake the sealed container well and let set for at least 30 minutes. Tincture of iodine typically comes packaged with its own dropper.

How to Filter and Purify Water Using Chlorine Bleach

The ratio for chlorine bleach is also based on liters. When using five percent chlorine bleach, which is found in most homes, add two drops per liter. If cloudy after filtering, double the amount. Never exceed 4 drops of chlorine bleach per liter. If the chlorine bleach you are using is less than five percent such as one percent chlorine, use 10 drops per liter, never exceeding 20 drops per liter. Some chlorine bleach can contain between 7 and 10 percent chlorine, if this is the case, only use one drop per liter and do not add more than two drops per liter. The water once treated must set for at least 30 minutes. Do not use the dropper from the iodine bottle. Purchase and carry an eyedropper specifically for the bleach.

One thought on “Survival Skills: How to Purify Water”

  1. Boiling water kills any biologicals that are in it, but it does not “purify” water. It does not remove any harmful chemicals, or heavy metals. Iodine can harm people with thyroid problems, or the fetus of pregnant women. Those warnings are on the labels of iodine tablets so it probably harms you as well, even if its not immediately apparent. It is a well established fact that chlorine does harm the body over time. Do the research on the net. Besides they both make the water taste like it’s coming from the drain pipe at a chemical plant. Most residential city water has lead because the old pipes leading up to the houses were joined with lead sauder, as well as having floride which is also toxic and accumulative in the body. If all your worried about is the biological hazards then boil it. And don’t wash the ashes off the hard wood charcoal with dirty water that has not been boiled.

    My prefered method is a combination of several methods of cleaning the water the best I can in primitive conditions. It is a little expensive, but is the cleanest water you can drink in the wilderness or a catastrophy situation. It’s even cleaner then what comes out of most peoples tap. It is way cheaper then some highend filters today and alot better, and use up about the same amount of room in my pack. I bought a 1 micron biodiesel filter online, (pack of five washable filters for $25.00) and two gravity feed .1 and .2 micron water filters (Point One 3-Way Inline Water Filter $45.00, and the Platypus Gravity Works $109.00) and use parts of both. I also made an additional filter of 1″ PVC 7 inches long to put hardwood charcoal into for filtering chemicals and heavy metals.

    This is how it works. I have a Camelback 2 litre water blatter and 2 Stanley 1 litre Munti-use bottle/cups. I use the hoses, the quick connectors, and the filter of the Sawyer, plus the dirty bag of the Platypus. I forgot to mention, I use my REI 10 litre camp bucket ($10.00) that folds up into its own pouch to the size of pack of Camel short cigarets to collect my water. I take it back to my base camp where I filter the water through a funnel I made from the biodiesel filter into the 4 litre Platypus dirty bag. (You can find the instructions to make this funnel on youtube under the title “Homemade ultralight one micron backpacking water filter”.) Anyway a hose runs from the Platypus dirty bag (that holds the prefiltered water down to 1 micron) to the sawyer filter that filters it down to .1 microns. A few inches further down the hose is my home made hardwood charcoal filter made from PVC. By the time the water flows through these filters all biologicals that I would worry about are gone, as well as all the chemicals and heavy metals that I am capable of removing. If I suspect that virus’s might be present (highly unlikely in North America) I use the completely non toxic and highly beneficial to your health, Aerobic 07 Stabalized Oxygen and wait 1/2 to 1 hour before drinking. (Aerobic 07 kills all harmful biologicals and is used by NATO) The Sawyer filter has a 1 million gallon guarantee with proper backflushing, and Platypus has a 1500 Litre. I use the platypus for a backup. All the filters have quick connections and my Camelback can be fitted with the filters quickly so I can fill it with dirty water and drink clean water from the bite valve if I,m in a hurry.

    In my small emergency survival kit which I carry in my day pack, I carry Katadyne Micropur Mp1 tablets, my Stanley 1 litre water bottle/cup which holds my small survival kit inside it has a stainless bottom that screws off to boil water or cook in. It also it has a bandana in it for prefiltering, my small bottle of Aerobic 07, and four foot of hose for those hard to reach water places like small rain puddles. Drop in Katadyne tablets wait and then drink with the bandana straining out the big stuff.

Leave a Reply

Your email address will not be published. Required fields are marked *