How To Disinfect Water
"Water makes up about 60-70 percent of our body and plays a role in virtually every function in the body — from keeping our blood flowing, our skin healthy and right down to our ability to blink our eyes," Wendy Bazilian, DrPH, RD and author of The SuperFoodsRx Diet says. "Water is our most important nutrient."
Most Americans have the luxury of going to a sink and with the turn of a knob they have access to unlimited drinking water. When you consider living off grid, wilderness survival or the possibility of a crisis situation, it goes without saying that you should be educated and well prepared in every way possible.
In the wilderness you have depend on your own safe drinking water procuring know-how, and keep in mind the fact that it can take some work and time procuring just a few sips of water. Considering how much water we need to stay properly hydrated, don't wait until thirst has set in to make procuring water a top priority.
You could find your next drink in a fast flowing river, a muddy puddle or a tiny pool of week old, bug laden rain water in a groove in a rock. No matter the source (or the flavor!) of the water, it is crucial to your survival that you drink enough or collect water when it's available, and you need to know how to disinfect the water.
You can filter out most of the dirt and bugs through a piece of cloth. Your main concern is actually the disease causing culprits you can't see with your naked eye, waterborne pathogens.
Human and animal waste are the main causes of waterborne pathogens (or microorganisms that live in water that can make you very sick). On this page you'll learn more about distinguishing safe drinkable water from water that should without-a-doubt be disinfected.
If grazing or farming is permitted on or near the land you are exploring, perhaps your best treatment option is boiling—or simply moving on to less-suspicious water sources.
Pesticides, herbicides and other toxins and pollutants associated with agriculture and urban development do not normally impact water sources found deep in wilderness areas. Recreational lands close to communities or farmlands may be more susceptible to such contaminants.
Microcystis From Blue-Green Algae
Cyanobacteria occur worldwide especially in calm, nutrient-rich waters such as freshwater lakes and rivers around the country. When in bloom, it secretes toxins such as microcystins, which can cause liver damage in animals including humans. Cyanobacteria are also known as blue-green algae, are so named because these organisms have characteristics of both algae and bacteria, although they are now classified as bacteria.
With the right conditions, its numbers can explode quickly, and are not only a threat to communities, but are a growing threat to backcountry water too. Normally, if water comes from an underground source, blue-green algae isn't an issue, or if the water is treated by water treatment facilities, this is sufficient to remove these toxins. However, when algae bloom is abundant, and the water source is a lake or pond, such as during the Toledo, Ohio scare in 2013, these methods can become insufficient. No one should ingest raw lake or pond water at any time, and bathing or washing food or dishes in contaminated water should be avoided.
According to the "Walkerton Clean Water Centre" which is a government agency of Ontario, Canada, the best options for removing mycrocystins are carbon based filters, which are 99% effective, and reverse osmosis water filtration, which is 99.9% effective. Boiling water does not remove blue-green algal toxins from the water. Due to the nature of blue-green algae toxins, using a solar still to distill the water isn't considered effective either.
ALWAYS treat any water that shows an algae bloom or harbors significant floating algae, but avoid it if at all possible. It's impossible to detect the presence of toxins in the water by taste, odor or appearance.
Waterborne Disease Causing Agents
It's possible that any water source on Earth could contain waterborne pathogens. The U.S. Environmental Protection Agency reports that 90 percent of the world’s water is contaminated in some way. The contamination by human and animal waste is measured in microns (aka micrometers). A micron equals one-millionth of a meter. (The period at the end of this sentence is roughly 500 microns wide.) The abbreviation for microns (μm) uses the Greek letter Mu.
Below is a list of the main waterborne disease-causing agents, from the largest to the smallest:
Examples: Cryptosporidium parvum, Giardia lamblia.
Size: Protozoa are single-cell parasites that range between 1 to 20 microns. Cryptosporidium (aka "crypto") typically measures between 4 to 6 μm; Giardia cysts range between 1 and 10 μm.
When symptoms appear: From 2 days to a few weeks. Individual protozoa are capable of causing infection.
Characteristics: Cryptosporidium and Giardia can both survive weeks, even months, in cold water. Crypto is a thick-walled egg (an oocyst). Its shell serves as a protective layer for the organism. In still water, the shell's weight usually causes the cyst to sink. The shell also boosts the resistance of Cryptosporidium to disinfectants such as iodine and chlorine.
Symptoms: Profuse, often watery diarrhea, vomiting, gas and intestinal discomfort. Most infections last 1 to 6 weeks; rare chronic cases can last up to a year. People with weakened immune systems need to be extra vigilant against contracting cryptosporidiosis.
Precautionary measures: Boiling, mechanical filtration/purification; UV light. Chemicals and halogens are effective against Giardia, but not always Cryptosporidium.
Examples: Escherichia coli (E. coli), Salmonella, Campylobacter jejuni, Yersinia entercolitica, Leptospira interrogans and many others.
Size: 0.1 to 10 microns.
When symptoms appear: From a few days to a few weeks. The number needed to cause infection can vary widely. With Salmonella, for example, infection may require ingesting just a handful of organisms or several thousand.
Symptoms: Diarrhea and potentially prolonged intestinal discomfort. A more serious bacteria-caused disorder, cholera, is rarely encountered in the United States but is fairly common in some countries. It is usually associated with dehydration. It can result in death if not quickly treated.
Precautionary measures: Boiling, mechanical filtration/purification; UV light; chemicals/halogens.
Examples: Hepatitis A, rotavirus, enterovirus, norovirus.
Size: 0.04 to 0.1 micron.
When symptoms appear: From 1 day to several weeks.
Symptoms: Diarrhea, intestinal discomfort. Potentially a variety of other ailments.
Precautionary measures: Boiling, purification; UV light; chemicals/halogens (though contact time, ranging from 5 minutes to 4 hours, is required).
Warning Signs When You're Seeking Drinkable Water
If you're going to be in the backcountry, learn to discern backcountry water. Before deciding to drink untreated water, wilderness travelers should look for danger signs around a water source. Consider treating water if you spot any of the following cautionary tipoffs:
- Water (particularly at lower elevations) near meadows or pastures where animals have grazed or near popular, established campsites.
- Evidence of pack animal traffic or other domesticated animal activity.
- Signs of sloppy human behavior or a prolonged human visit.
If no such signs are apparent, a water source (particularly any at elevations exceeding 7,000 feet) may offer some of the purest, most delectable water on the planet.
How Do You Know If Water's Safe To Drink?
Put simply, it's hard to. With the possibility of bacterial and viral contamination, chemical pollutants, and the potential for animal waste and carcasses upstream in other areas, it's imperative that you have the skills to properly purify drinking water. How you go about treating your water depends on your situation, but when in doubt, be safe rather than sorry.
If you don't have chemical disinfectants or filters, then boiling water is the way to go. (One reason why knowing how to build a fire is so important!) Boiling is a common and reliable way of disinfecting water. *Remember, boiling, filtering, or chemically treating water can remove or kill microorganisms, but it will not remove all synthetic chemical toxins. (This is also the case when using a solar still)
Boil Your Water
Most germs die quickly at high temperatures. The CDC says that water that has been boiled for 1 minute is safe to drink after it has cooled. If no other method of water disinfection is available, very hot tap water may be safe to drink if it has been in the tank for a while. Boiled water will taste better if you put oxygen back into it by pouring the water back and forth between two clean containers. (This will also improve the taste of stored water)
•Boil water vigorously for 1 minute and allow it to cool to room temperature (do not add ice).
•At altitudes greater than 5280, boil water for 3 minutes or use chemical disinfection after water has been boiled for 1 minute. (The reason for the longer boiling time at higher elevations is that water boils at a lower temperature there, and giving your water a couple of extra minutes of boiling time ensures germs will be killed)
*Note that there is no benefit to exceeding these time limits. All that will do is cause some of your precious drinking water go up in steam.
Chemical disinfection is when you add enough of a chemical to your water to kill the germs, but still providing yourself with a safe drink of water. Tablets or packets of powder can be bought at camping stores to disinfect water. These usually combine chemical disinfectants (such as chlorine or iodine) with a substance that makes the water clear and improves its taste. Follow the instructions on the package closely—you may need to wait several hours until all the germs are killed.
In a disaster situation, The American Red Cross recommends that the only agent that should be used to treat water should be household liquid bleach. Other chemicals, such as iodine or water treatment products sold in camping or surplus stores that do not contain 5.25 percent sodium hypochlorite as the only active ingredient, are not recommended for use by the American Red Cross.
It's a good idea to try out products at home before using them in the wild to make sure you don't have any adverse reactions to the chemical you're using. It's recommended that you limit the time you will be using iodine to a few weeks.
The colder the water, the less effective the chemical is as a purifying agent. Research has shown that at 50' F (10' C), only 90 percent of Giardia cysts were inactivated after 30 minutes of exposure. If the water temperature is below 40' F (4' C), double the treatment time before drinking. It is best if water is at least 60' F (16' C) before treating. You can place the water in the sun to warm it before treating.
Chemically treated water can be made to taste better by pouring it back and forth between containers, after it has been adequately treated. Other methods include adding a pinch of salt per quart or adding flavorings (e.g., lemonade mix, etc.) after the chemical treatment period.
•Follow the tablet manufacturers' instructions.
•If water is cloudy, double the number of tablets.
•If water is extremely cold, less than 5° C (41° F), an attempt should be made to warm the water, and the recommended contact time (standing time between adding a chemical disinfectant to the water and drinking the water) should be increased to achieve reliable disinfection.
Note: Be sure the tablet size is correct for a liter of water.
Tincture of Iodine - measure out your dose to water.
•If using tincture of iodine 2% solution, add 5 drops to a Liter or Quart of clear water.
•If the water is cloudy, add 10 drops per Liter or Quart. (Note: 20 drops=1 ml.)
•Allow the water to stand for 30 minutes before drinking when the water temperature is at least 25°C (77°F). Increase the standing time for colder water: (e.g., for each 10° less than 25°C (77°F), allow the water to stand for double the time before drinking it.
*Do NOT disinfect water with iodine if you have a thyroid issue, an allergy to iodine or if you're pregnant.
Clear water - Use 1/8 teaspoon or 8 drops of unscented bleach to one gallon (16 cups) of clear water. Mix well and wait 30 minutes before drinking.
Cloudy water - Use 1/4 teaspoon or 16 drops of unscented bleach to one gallon (16 cups) of cloudy water. Mix well and wait 30 minutes before drinking.
*NEVER mix bleach with ammonia or other cleaners.
*Always ensure adequate ventilation when using bleach.
Chlorine dioxide tablets are another disinfectant that now is available in some outdoor stores. This disinfectant has proven to be effective against pathogens, including Cryptosporidium, if the manufacturer’s instructions are followed.
Sanitize Containers Before Storing Drinking Water
1. Using unscented bleach, mix 1 teaspoon (64 drops or 5 milliliters) of bleach to one quart (32 ounces, 4 cups or about 1 liter) of water.
2. Pour this in a clean storage container and shake well, making sure that the solution coats the entire inside of the container.
3. Let sit for at least 30 seconds, then pour out the solution.
4. Allow to air dry or rinse with water that has already been made safe, if available.
Other Water Disinfection Methods
Use Water Filters
A variety of filters are available from camping stores. Most have filter sizes between 0.1 and 0.4 microns, which will remove bacteria from water but will not remove viruses. New “hollow fiber” technology can remove viruses as well. “Reverse osmosis” filters remove bacteria and viruses and can also remove salt from water, which is important for ocean voyagers.
Carbon components in filters and purifiers will remove some (but not all) organic chemicals (pesticides, herbicides, mine tailings, etc.) and inorganic chemicals (such as arsenic and mercury). Carbon often also removes objectionable tastes and odors.
Ultraviolet (UV) Light
Portable units that deliver a measured dose of UV light are an effective way to disinfect small quantities of clear water. UV light can kill bacteria and microorganisms in water because the energy emitted by the light is absorbed by the cells of microbes which prevents the cell enzymes from “reading” DNA. Without intact DNA microbes cannot reproduce. However, this technique is less effective in cloudy water since germs may be shielded from the light by small particles.
In an emergency situation, water can be disinfected with sunlight. Water in a clear plastic bottle, preferably lying on a reflective surface (such as aluminum foil), will be safe to drink after a minimum of 6 hours in bright sunlight. This technique does not work on cloudy water.
The Four Main Steps To Water Filtration
The entire filtration process generally has 4 main steps, coagulation, sedimentation, filtration and disinfection.
1. Coagulation: removes dirt, metals and other particles suspended
in water. Chemicals like Alum are added to the water that form
sticky particles called “floc” which attract the dirt particles.
2. Sedimentation: the combined weight of the sediment and
chemicals stuck together become heavy and sink to the bottom.
3. Filtration: smaller particles are removed as water passes through
a series of filters (sand, gravel, charcoal)
4. Disinfection: if necessary to kill bacteria or microorganisms found in the water, boiling or chemically disinfecting the water is necessary.