Comments Off on Water Survival – Purification-& Filtration

The average human requires two quarts/liters of water daily just for hydration. During the course of a normal day, you will be hydrated from coffee, juices, teas, sodas and even certain foods, so you may not realize what it actually takes to keep your body hydrated. Once you find yourself lost or stranded water becomes critical to your survival. If the weather is hot, you may need up to one gallon/four liters daily just to replace lost fluids in a survival situation. Dehydration is fatal if not treated by consuming water. Once your body has lost 15 percent of its fluids, organs will begin to fail and this can happen in less than 72 hours if you are sweating heavily, have diarrhea or are vomiting. Body fluids must be replaced, as they are lost.

Wilderness Surface Water Sources

Rivers, lakes, ponds, streams and natural springs are all water sources that you would find in the wilderness. However, surface water will contain bacteria, pathogens and parasites. Animal feces, carcasses of animals, insects, geese, ducks and even humans can contaminate a water source. Consuming contaminated water can cause illnesses that can be fatal in some cases and many times will cause vomiting and diarrhea, which will accelerate dehydration. Surface water must be first filtered and then purified by boiling or chemical treatment before it is considered safe to drink.




Boiling and chemical treatment is not always enough to destroy waterborne cysts. Cysts act as a protective barrier that protects bacteria. Certain cysts can withstand boiling and chemical treatment, and once in the digestive track stomach acids will break the cyst down allowing bacteria into your system. Filtering can remove most if of not all cysts from water if done properly. Cysts are best described as seedpods, or spores that are suspended in water.

A filtering device can be an empty can with a hole(s) in the bottom with filtering medium layered inside. You can also use a two-liter soda bottle. Filtering mediums include charcoal, sand, cheesecloth, coffee filters, gravel and crushed vegetation.

When layering your filtering mediums always place the least porous material at the bottom and the most porous or less dense material at the top. The gravel will filter out the large debris such as pieces of organic matter and insects while the next layer such as sand will begin removing finer particles until you reach the charcoal and cheesecloth, which will filter out even more finer particles including cysts and certain parasites. If you layer opposite of what is described, you will essential “clog” up the filtering mediums with large debris and your water will not filter sufficiently.

Boiling Water to Purify

Boiling is the preferred method but you may not always have access to fire or a vessel in which to boil water.

Remember water boils at lower temperatures at high elevations, for example, Denver Colorado is roughly one mile above sea level. Water boils at 212ᵒF/100ᵒC at sea level while one mile above sea level water boils at 203ᵒF/95ᵒC, which means it must boil longer to destroy waterborne contaminates. Boil for three minutes when you know you are substantially above sea level.

Parasites and bacteria are destroyed by prolonged immersion at a certain temperature. You will destroy all contaminates if you maintain a water temperature of 160ᵒF/70ᵒC for thirty minutes (pasteurization). Use this method if you do not have a container that can withstand high temperatures but would allow you to heat the water to the 160 degrees needed. You will destroy all contaminates by rapid boiling for one minute at 212ᵒF at sea level. If you are unsure of your elevation, boil for three minutes.

Boiling beyond the recommended times can cause you to boil your water away because of evaporation. You can literally boil a pot dry if you allow it to boil to long. Boiling longer than what is recommended has no effect on the purity of the water.


Two Percent Liquid Iodine (Tincture of Iodine)

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Liquid iodine can be found in most drug stores and retail stores with a pharmacy section. Usually the container will have its own dropper included and if not you will need a dropper for accurate measurements. Water once filtered can be disinfected using two percent liquid iodine by adding five drops per one-quart/liter of water or 20 drops to a gallon. Shake the containers well and wait 30 minutes after adding the drops before drinking.

Chlorine dioxide and iodine tablets are the most common water purification tablets that can be purchased in any camping store or camping section. Follow the manufactures directions carefully when using to disinfect a contaminated water source.

Morning Dew

Collect morning dew off grasses and other vegetation by absorbing the moisture using a clean cotton cloth. Squeeze the cloth directly into your mouth or a container. Some individuals claim they can gather up to several quarts a day this way.

Direct Rainfall

Absorb using cloth or collect it in a container as it runs off vegetation. If you collect rainfall from the ground, such as filled depressions after a rainfall it must be filtered and purified before you can drink it.


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