Purifying water is the most critical skill for backpackers, hunters, or anyone in the most basic survival situation. Water is necessary for everything and if you understand the basics of purifying water, then you will be far ahead of the average person. Here are the best 5 methods of purifying water.
Clean, purified water is essential to life
The unfortunate truth is that easy access to clean, potable water is often one of the first things to disappear during a catastrophe. A lack of clean water will quickly lead to dehydration and illness. The human body can survive without water for about 3 days, but keep in mind that it’s under ideal conditions. This means that the latter part of the time frame will be spent in agony. You don’t go from being alive and operating the way you usually do for 70 hours then suddenly dropping dead. It would be an agonizing and painful process.
We often take for granted how much water we use in a single day. We not only need water to drink, but we also need it to prepare food and clean ourselves, our clothes, and our dishes.
Let’s take a look at the water usage of the average person going about their daily routine:
- Morning shower (10 minutes): 15-20 gallons
- Toilet (used 4 times): 5 gallons
- Handwashing, teeth brushing, etc.: 10 gallons
- Washing clothes (one load): 30-40 gallons
- Dishwasher (one load): 4-6 gallons
That is between 60 and 80 gallons of water, not including water that is actually consumed or used to cook food for one person in an average day! After a disaster when water is not flowing from the taps, those activities will need to be altered. Tossing a load of clothes into the washer just won’t be an option. Dishes will need to be washed by hand( the water recycled for another purpose). And flushing the toilet may not be feasible. The one thing that will absolutely not change is your body’s need for hydration.
Why can’t you drink out of a stream?
You shouldn’t drink water directly from a stream because there could be bacteria, viruses, and chemical pollutants. Something as simple as deer droppings present in the stream where you get your drinking water could make you seriously ill or even kill you.
Some of the diseases that can happen as a result of drinking unpurified water include:
- Giardia
- Cholera
- Typhoid fever
- E-coli
- Dysentery
These are all very serious and not worth the risk. It is crucial that you make sure that your drinking water is safe.
Use safe water
After an emergency such as a hurricane, flood, or a water main break, your tap water may not be available or safe to you. In these situations it is crucial to know how to prevent illnesses caused by unsafe water.
After an emergency or disaster:
- If you suspect your water is unsafe, do not use that water to drink, bathe, brush your teeth, wash dishes, wash and prepare food, wash your hands, make ice, or use for baby formula.
- Only use bottled, boiled, or treated water for drinking, cooking, and personal hygiene.
- Follow the recommendations from your state or local health department for treating and boiling water.
- Never use water from boilers or radiators that are part of your home’s heating system. Learn about places inside and outside of your home where you might find other sources of safe water.
WARNING: Water that has fuel, toxic chemicals or radioactive materials CANNOT BE MADE SAFE by boiling or disinfecting. If you suspect that your water may be contaminated with fuel or toxic materials, use bottled water or find a different source.
Where to find your water source:
You can find sources of water in many places both inside and outside of your home. To find water sources inside your home, consider checking the water pipes, water heaters, toilets, and fish tanks. For water sources outside the home, look for nearby ponds, rivers, lakes, or any other body of water. The chart below will discuss potential water sources outside the home and the quality of water in each source.
Potential water sources outside the home:
| Water Source: | Quality: | Things to consider: |
| Puddle | Low | The least desirable water source is standing water because it is a breeding ground for insects and organisms. Puddles on the street are almost guaranteed to be contaminated by chemicals that have leached out of vehicles. |
| Slow-moving river through a town | Low | Since the water is flowing, it is a little more desirable than standing water, but still fairly risky. If the river is surrounded by urban developments then the contamination level will be very high. If the water is murky, that indicates a high level of particulates in the water. A source that is easily accessed by the public has a higher risk of contamination. |
| Lake or Pond | Moderate | Water in a pond or lake is standing and not flowing. This means that it could facilitate organisms and insects. Again, if a water source is easily accessed by the public then the risk of contamination will increase. Bodies of water that are located at high altitudes are generally cleaner because they are less likely to collect run off from farm lands, residential areas, and industrial sites. |
| Fast-moving mountainous river | High | Water that flows at a fairly fast rate is much more likely to be fresh. Being at a high altitude helps to keep contaminants from upstream at a minimum. A fairly remote location will mean that human induced contaminants are less likely. |
5 methods of purifying water
- Boiling water
- Bleach
- Portable Water filter
- Iodine
- Sunlight exposure
Method #1: Boil for decontamination
If you don’t have safe water, you should boil your water to make it safe to drink. Boiling is the surest method to kill disease-causing germs, including viruses, bacteria, and parasites.
You can improve the flat taste of boiled water by:
- Adding a pinch of salt per quart or liter of boiled water.
- OR. Pouring the water from one container to another and allowing it to sit for a few hours.
Steps for boiling water:
- Filter out the large particles in the water.
- Put the clear water in a pot.
- Bring the water to a rolling boil for 1 minute (at elevations above 6,500 feet, boil for 3 minutes.)
- Allow the boiled water to cool.
- Store the water in clean, sanitized containers with airtight covers.
- Drink Me.
“Bringing the water to 160°F for a duration of 30 minutes or 185°F for 5 minutes has the same effect as bringing it to a boil.”
The Wilderness Medical Society
Not many people know that it isn’t even necessary to bring the water to a full boil. The Wilderness Medical Society states that “Bringing the water to 160°F for a duration of 30 minutes or 185°F for 5 minutes has the same effect as bringing it to a boil.” Knowing this in a survival situation can be a life saver.
The downside to using this method is that it does nothing if there are chemical contaminants in the water.
Visit my guide to learn more about this method of water purification:
Method #2: Purify water with bleach (CDC recommendations)
If you don’t have bottled water and if boiling is impossible, you can make small quantities of safe drinking water by using a chemical disinfectant such as unscented household chlorine bleach, iodine, or chlorine dioxide tablets.
Disinfectants are not as effective as boiling at killing more resistant germs such as the parasites Cryptosporidium and Giardia, but they can kill most harmful or disease-causing viruses and bacteria.
*If you follow the manufacturer’s instructions correctly, chlorine dioxide tablets can kill cryptosporidium.
It’s important to know that bleach comes in different concentrations. Read the label of the bleach you are using to find its concentration before you start to disinfect water.
Steps to disinfect water with bleach:
If the water appears cloudy, filter it through a clean cloth, paper towel, or coffee filter OR allow it to settle. Then, draw off the clear water and proceed to the following steps.
- Locate a clean medicine dropper, teaspoon, or metric measure (milliliters) from your medicine cabinet or emergency supply kit.
- Locate fresh liquid chlorine bleach that has been stored at room temperature for less than a year.
- If the label doesn’t have instructions for disinfecting drinking water, check the “active ingredient” on the label to find the sodium hypochlorite percentage. Then use the info in the tables below as a guide.
- Thoroughly stir the mixture.
- Let it stand for at least 30 minutes so that the bleach can adequately disinfect the water.
- Make sure that the water has a faint chlorine smell.
- Store the disinfected water in sanitized containers with airtight covers.
- Drink.
To disinfect water using bleach that has a 5%-9% concentration of sodium hypochlorite (most common in the US.) If the water is cloudy, murky, colored, or very cold, double the amount of bleach listed below
| 1 quart/ liter of water | 1 gallon of water | 5 gallons of water |
| If you have a dropper: Add 2 drops of bleach | If you have a dropper: Add 8 drops of bleach | If you have a dropper: Add 40 drops of bleach |
| If you have something that measures milliliters(mL): Add 0.1 mL of bleach | If you have something that measures milliliters(mL): Add 1/2 mL of bleach | If you have something that measures milliliters(mL): Add 2 and 1/2 mL of bleach |
| If you have a measuring spoon: Add a tiny amount (too small to measure) | If you have a measuring spoon: Add a little less than 1/8 teaspoon | If you have a measuring spoon: Add 1/2 teaspoon of bleach |
To disinfect water using bleach that has a 1% concentration of sodium hypochlorite (this concentration is not common in the US, but is used in other countries.) If the water is cloudy, murky, colored, or very cold, double the amount of bleach listed below
| 1 quart/ liter of water | 1 gallon of water | 5 gallons of water |
| If you have a dropper: Add 10 drops of bleach | If you have a dropper: Add 40 drops of bleach | If you have a dropper: Add 200 drops of bleach |
| If you have something that measures milliliters(mL): Add 1/2 mL of bleach | If you have something that measures milliliters(mL): Add 2 and 1/2 mL of bleach | If you have something that measures milliliters(mL): Add 12 and 1/2 mL of bleach |
| If you have a measuring spoon: Add 1/8 teaspoon of bleach | If you have a measuring spoon: Add 1/2 teaspoon of bleach | If you have a measuring spoon: Add 2 and 1/2 teaspoon of bleach |
After the water stands for 30 minutes do a smell test. If the water has a faint chlorine smell, then you are done and can consume the water. If not, repeat the process adding the same amount of chlorine, mix, then let it stand for 30 more minutes.
At this point, if the water still doesn’t have a faint smell of chlorine, then you should discard the water and find a cleaner source. Once you are satisfied with the treatment of your water, it is a good time to aerate the water. This will assist in the evaporation of the chlorine prior to consumption. The easiest way to do this is to pour the water back in forth between two sanitized containers a few times.
Research has shown that the colder the water is, the less effective chemical treatments are at purifying water. The ideal temperature for the water for chemical treatment is at least 60 °F.
Note: Though not required, it is ideal to use the boiling and bleach treatments in conjunction to ensure the maximum effectiveness for purifying water. Make sure that you boil the water first then follow it with the bleach method.
Method #3: Use a Portable Water Filter
There are small, portable water filters that were originally created for backpackers who spend long periods of time in the wilderness. Water is very heavy and when you spend that much time away from the comforts of running tap water, it is unrealistic to carry the water that you need. Instead, you will need a way to purify the water that you find on your journey.
These filters have been a long-standing solution for both preppers and survivalists. This filter type utilizes a ceramic filter element to filter out bacteria and other undesirable particles. Additionally, the filter contains carbon will remove most chemical contaminants. These filters are light, very portable, and will generally process hundreds of gallons. The modern filters are rechargeable.
If you are choosing a portable water filter:
- Pick one that has a filter pore size that is small enough (absolute pore size of 1 micron or smaller) to remove parasites such as Giardia and Cryptosporidium. Portable water filters do not remove viruses, and most portable filters do not remove bacteria either.
- Carefully read and follow the manufacturer’s instructions for the specific water filter you are using.
- After filtering, add a disinfectant such as iodine or chlorine to the filtered water to kill any viruses and bacteria.
For more information about water filters that can remove parasites, see CDC’s A Guide to Water Filters.
Using a portable water filter:
- Put the intake of the filter into the water source.
- Push or pump water through the filter element.
- Collect the filtered water and store in a clean, tight container.
- Drink up.
Sizes of harmful organisms:
| Type: | Examples: | Spore size: | Necessary filter type: |
| Protozoa | Giardia, Cryptosporidium | 5 microns or larger | Water filter |
| Bacteria | E. coli, Cholera, Salmonella | 0.2 – 0.5 microns | Microfilter |
| Viruses | Hepatitis A, Rotavirus, Norwalk virus | 0.004 microns | Water purifier |
Method #4: Iodine Water Purification
Using iodine to disinfect water is not the most popular method, but it is a great skill to have in your toolbox. In addition to being a good water purifier, iodine also works well as a wound disinfectant and it is has a good shelf life.
Iodine, tablets with iodine(tetraglycine hydroperiodide), or chlorine tablets kill most germs, but not Cryptosporidium. Water that has been disinfected with iodine is NOT recommended for pregnant women, people with thyroid problems, people on lithium, women over the age of 50, or those with known hypersensitivity to iodine. Some people with shellfish allergies are also allergic to iodine. It’s also not recommended for continuous use—don’t use it for more than a few weeks at a time.
Also, iodine is sensitive to sunlight and should be stored in a dark place or in a dark colored container.
Purifying water with iodine
To use iodine, go to your local pharmacy and pick up an iodine solution called “Iodine Tincture” with a 2% USP content. “USP” refers to the concentration of iodine in the solution.
- Filter out the large particles in the water.
- Add 5 to 10 drops of iodine per liter of water.
- Let the water sit for a minimum of 20 minutes.
- You can optionally add a powdered drink mix to enhance the flavor.
- Drink.
Iodine works best in warm water. If you suspect that the water may have a high number of pathogens or if the water is cold, allow the water to sit for at least 30 minutes after adding the iodine. You can safely increase the iodine to no more than 10 drops per liter of water.
After treating the water with iodine, you will notice a distinct taste. This is normal and does not indicate that the water is unsafe to drink. This is why survivalists and preppers often pack drink mix to disguise the iodine flavor.
Method #5: Sunlight Exposure (SODIS)
The ultra-violet rays in sunlight can naturally kill germs in water. This makes it possible to render water safe to drink by exposing it to sunlight for a prolonged period of time. This method is known as SODIS or Solar Water Disinfection.
*If the water has a harmful chemical or radioactive material in it, solar disinfection will not make it drinkable.
Solar disinfection is a method that utilizes heat and UV radiation to kill parasites and bacteria in the water. Solar disinfection works by placing contaminated water in a transparent container and exposing it to strong sunlight for 6 to 8 hours if sunny, or 2 full days (if cloudy.)
This method is appropriate when the water is clean and clear and transparent containers for the treatment are available.
Make sure that the water is as clear as possible before applying this method. If the water is murky or contains a lot of particles, filter it first through fabric or any kind of improvised filtration system to get it as clear as possible.
How to use sunlight to disinfect water:
- Find a clear glass or plastic water bottle that is no larger than 2 liters (smaller is better.)
- Remove any labels and make sure that the container is as clear as possible.
- Fill container with the water that needs the treatment.
- Lay the bottle on a flat, level surface with direct exposure to the sun.
- Let it sit for 6-8 hours in the sunlight (or 2 days if it’s cloudy.)
- Shake the water vigorously.
- Drink.
Water purification in hot climates using sunlight: SODIS Method | PeakSurvival
It is good to be familiar with this method because all you need is a clear, plastic (or glass) bottle, water, and some sunlight. Since the water needs to be exposed to direct sunlight in order to destroy any organisms it contains, keep in mind that the larger the container is, the harder it will be to kill the organisms inside. The more water that the sunlight needs to travel through, the less effective it is at killing organisms at the bottom of the container.
The most important survival skill you can having is knowing multiple methods of water purification. If you are familiar with these methods and proficient at applying them, you should be able to make water drinkable even in the worst conditions.
If you are concerned about water quality, you can always combine methods such as filtering the water first then treating it chemically. It is worthwhile to spend more time treating your water or even treating the water twice. Clean and purified drinking water is essential to survival.
Have you ever tried any of these methods before? Are there some methods that seem more dependable than others to you? Comment below to share your thoughts.
See you soon!
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