Water purification tablestRainwater collected in clean containers or from plants is usually safe for drinking. However, water gathered from lakes, ponds, streams, rivers, or swamps should be purified, especially if the water source is near human settlements or in tropical environments.  When possible, purify all water you get from vegetation or from the ground by boiling or using iodine or chlorine. Commercial water purifiers and filters can also be used and should be a part of your survival kit.  After purifying a canteen of water, you must partially unscrew the cap and turn the canteen upside down to rinse unpurified water from the threads of the canteen where your mouth touches.  Even the slightest drop of contaminated water on a container or your hands can cause illness.

Methods to purify water

You can use the following methods to purify water.  If the water is cloudy, you may pour it through a cloth or coffee filter to filter the water before beginning the purification process.  A coffee filter will not purify water but it will remove the large particles (which may only be purified on the “outside”).

  • Commercial water purification tablets. (follow the directions provided with the product).  Water purification tablets contain disinfection agents such as chlorine and agents that cause impurities to clump and/or dissolve.
  • Place 5 drops of 2 percent tincture of iodine in a container (about the size of a canteen) full of clear water. If the water is cloudy or is cold, use 10 drops.   Let the water stand for 30 minutes before drinking.  Adding powered vitamin C will kill the iodine taste and odor.  Note that iodine is light sensitive and must be stored in a dark bottle.  Also, many people are allergic to iodine and it should not be used by persons with thyroid problems.
  • Use 2 drops of 10 percent (military strength) povidone-iodine or 1 percent titrated povidone-iodine. The civilian equivalent is usually 2 percent strength, so 10 drops will be needed. Let stand for 30 minutes. If the water is cold and clear, wait 60 minutes. If it’s very cold or cloudy, add 4 drops and wait 60 minutes.
  • Place 2 drops of chlorine bleach (5.25 percent sodium hypochlorite) in a canteen of water. Let stand 30 minutes. If the water is cold or cloudy, wait 60 minutes. Remember that not all bleach is the same around the world; check the available level of sodium hypochlorite in the product.
  • The antiseptic potassium permanganate, commonly marketed as Condy’s Crystals, can be used for for a number of applications, including emergency disinfection of water. The crystals are of a non-uniform size, so you must judge the actual dosage by the color of the water after adding the crystals. Add three small crystals to 1 liter (1 quart) of water. If the water turns a bright pink after waiting 30 minutes, the water is considered purified. If the water turns a dark pink, there is too much potassium permanganate to drink safely. Either add more water to dilute the mixture or save it for use as an antiseptic solution. If the water becomes a full red, like the color of cranberry juice, the solution
    may be used as an antifungal solution.
  • Boil your drinking water. Boiling water is the most certain way of killing all microorganisms and is the safest method of purifying your drinking water. By achieving a rolling boil, you can ensure that you are destroying all living waterborne pathogens.

Note: If using chemical agents to disinfect water, you must be sure they have not expired.  Once chemical products have been opened, they begin to degrade rapidly.

Dangers in impure water

Giardia microorganismBy drinking non-potable water you may contract diseases or swallow organisms that can harm you and may easily lead to potentially fatal waterborne illnesses.  Two of the most prevalent pathogens found in most water sources throughout the world are:

  • Giardia, which causes Giardiasis (beaver fever). It is characterized by an explosive, watery diarrhea, excessive gas, and upset stomach accompanied by severe cramps.  1-2 days of diarrhea is followed by 4-7 days of constipation, still with upset stomach and cramps.  The infection can last for 2-6 weeks or longer.
  • Cryptosporidium, which causes Cryptosporidiosis (also known as Crypto). It is much like Giardiasis, only more severe and prolonged, and there is no known cure but time. Crypto can be fatal.  Symptoms appear 2-7 days after infection.  Diarrhea may be mild, watery, with mucus, and can last from 3 days to 2 weeks. There are often stomach cramps, and lower fever.  Other symptoms include vomiting and dehydration.  It can spread from the intestines to the lungs, ears, stomach, and pancreas.  NOTE: The only effective means of neutralizing Cryptosporidium is by boiling or by using a commercial microfilter or reverse-osmosis filtration system. Chemical disinfectants such as iodine tablets or bleach have not shown to be 100 percent effective in eliminating Cryptosporidium.

Examples of other diseases or organisms are:

  • Dysentery. You may experience severe, prolonged diarrhea with bloody or mucus tainted stools, fever, abdominal pain, and weakness.  You may experience frequent, passage of feces.  If left untreated it may be fatal.
  • Cholera and typhoid. You may be susceptible to these diseases regardless of inoculations. Cholera can cause profuse, watery diarrhea, vomiting, and leg cramps.  The severity of the diarrhea may lead to dehydration and electrolyte imbalance.  Typhoid symptoms include fever, headache, loss of appetite, constipation, and bleeding in the bowel.
  • Hepatitis A. This is an infectious disease of the kidney.  Symptoms include diarrhea, abdominal pain, jaundice, and dark urine. The time between infection and the appearance of symptoms can be between two and six weeks.  This infection can spread through close person-to-person contact or ingestion of contaminated water or food.
  • Flukes. Stagnant, polluted water—especially in tropical areas—often contains blood flukes. If you swallow flukes, they will bore into the bloodstream, live as parasites, and cause disease.
  • Leeches. If you swallow a leech, it can hook onto the throat passage or inside the nose. It will suck blood, create a wound, and move to another area. Each bleeding wound may become infected.