Water Purification

Purifying water is the most critical piece of knowledge for self sufficient living after a major disaster. It is vitally important that you have a solid understanding about how this is accomplished. Water is needed for just about everything, and if you know the basics of purifying water you’ll be miles ahead of the average person. Any local stream, water reservoir, or lake will become a critical resource that you can use to ensure your survival.

Importance of Knowing How to Purify Water


In a major disaster, where all the basic utilities that you rely upon in your daily life are not available to you, knowledge of self sufficiency will be critical.

Food and water are most critical to your survival, and humans can last a few weeks without food but only a few days without water. If you can secure a means of acquiring fresh water, then you just bought you and your family a whole lot of time to figure out everything else.

So why can’t you just drink out of a stream if you needed water? Well that’s because of bacteria, viruses, and chemical pollutants. Something as simple as deer droppings up stream from you could cause you serious problems.

Diseases that can result from drinking unpurified water include Giardia, Cholera, Typhoid Fever, E-Coli, and Dysentery. These are all very serious diseases and if you become affected by one of these while in a crisis situation it’s going to make surviving a catastrophe much more difficult. ALWAYS ENSURE YOU ARE DRINKING CLEAN WATER!


Standing Puddle

What to Consider…

  • Standing water is the least desirable source as the water often is a breading ground for organisms and insects.
  • Puddles on the street are almost always contaminated with chemicals that have leached out of vehicles.
  • Once the puddle is dried up it probably wont return until the next rains.

Source Quality: LOW

  • Water is flowing which is much more desirable than standing water.
  • The river is surrounded by urban developments making the risk of contamination very high.
  • The water appears murky indicating a high number of particulates in the water.
  • It appears to be easily accessibly by the public adding further risk of contamination.

Source Quality: LOW

Pond or Lake
  • Water is standing and not flowing, could facilitate organisms and insects.
  • Body of water appears to be open for public use. This presents more of a risk of contamination.
  • Appears to be large enough to provide a significant amount of water.
  • Is this source located at a high or low altitude? Higher altitude bodies of water are generally cleaner as they are less likely to collect run off from farm lands or industrial sites.

Source Quality: MODERATE

  • Water is flowing at a fairly fast rate helping to ensure the water is fresh.
  • There is snow along the banks which indicates the water is probably snow run off and therefore fairly fresh.
  • Being at a high altitude helps to keep contaminants from upstream to a minimum.
  • It appears to be fairly remote meaning human-induced contaminants are less likely.

Source Quality: HIGH

Boiling Water for Decontamination

Most preppers are very familiar with the fact that you can boil water as a means of making it biologically safe to drink. Boiling the water will kill bacteria and any organisms that might be in the water. This wont remove any chemical contaminants from the water but at least you know you wont be getting Giardia along with all of it’s nasty symptoms in the middle of a crisis situation.It is also critical that you filter the large contaminants our of the water prior to boiling the water for drinking purposes. Even something as simple as a wet t-shirt folded over itself a few times will work to accomplish this. Pour the water through the t-shirt to ensure no large debris particles remain.

9875492Not many preppers know that it isn’t even necessary to bring the water to a boil. According to the Wilderness Medical Society, bringing the water to 160°F for a duration of 30 minutes or 185°F for 5 minutes has the same affect as bringing it to a boil. However, once the water reaches the boiling stage it is safe to assume that the water is hot enough to kill any organisms (no matter how long the water remains at the boiling stage).

Knowing this can be a big help to you as a prepper. Now you know that if you have a fuel efficient way to bring your water up to 160°F for 30 minutes, then you will have biologically safe water to drink. Preppers have done this with things such as solar cookers.
The downside to using this as a means to purify water is that (as stated above) it does nothing if there are chemical contaminants in the water. The water also needs to cool down prior to drinking it.

If you want to take further precautions to ensure your drinking water is safe for consumption, consider also treating the water with bleach.

Purifying Water with Bleach

1237493Purifying water for drinking using bleach is very practical and doesn’t take the same about of energy to accomplish as boiling water does. In this method you can add a small amount of standard bleach to the water which will make it biologically safe to drink. Using the correct amount of bleach will kill any organisms in the water while still keeping the chlorine levels low enough so that it is safe for human consumption.

When you buy bleach for this purpose make sure that the active ingredient is sodium hypochlorite (NaOCl) with a concentration of between 5.25% and 6%. Some manufactures add Sodium Hydroxide as an active ingredient as well. This additional active ingredient is safe and will not pose any health risk when purifying water.

It is critical to ensure that it is standard bleach with NO additives (such as scented bleach).

Prior to starting this process make sure that you do something to filter out the large particles of debris (see the section on boiling water). Add 16 drops of bleach per gallon of water (or 8 drops per 2 liter water bottle) and mix thoroughly. Let the water stand for 30 minutes so that the bleach can adequately disinfect the water.

After the water has sat for 30 minutes, smell the water. If there is a faint smell of chlorine, then you are done and can consume the water. If not, repeat the process by adding 16 more drops of bleach (or 8 drops per 2 liter water bottle), mix, and allow it to stand for 30 minutes.

If the water does not have the faint smell of chlorine at this point, it is best to discard the water and find a new cleaner source. Once you are satisfied with the treatment of the water, you may want to aerate the water to assist in evaporation of the chlorine (which will help the water taste better) prior to consumption. An easy way to do this is to pour the water back and forth between two containers a few times.

Research has shown that the colder the water, the less effective chemical treatments such as this are at purifying water. One study showed that at 50°F, chemical treatment left as much as 10% of Giardia particles alive in the water after 30 minutes of exposure to the chemical treatment. If you are in doubt as to if the water is at the optimal temperature, just allow the water to sit longer than the 30 minutes prior to consumption. Ideal temperature for the water for chemical treatment is at least 60 °F.

Note: Although not required, it is best to use the boiling and bleach treatment methods in conjunction to ensure maximum effectiveness with purifying the water. When doing this make sure you boil the water first and THEN do the bleach treatment.

See the American Red Cross’s recommendations for water treatment

Using a Portable Water Filter

These small portable water filters were originally created for backpackers who spend days on end in the wilderness. When you are spending that much time away from the comforts of a running tap, you can’t carry the required amount of water with you, so you’ll need to find a way to purify what you find.

This is type of filter has been a long standing solution to this problem and it’s great for survivalists and preppers alike. This type of filter uses a ceramic filter element to filter out the bacteria and other unwanted particles. It’s filter also contains carbon which will also remove most chemical contaminants. These are light (about a pound) and highly mobile. These types of filters will generally process hundreds of gallons and the modern filters are rechargeable. So you don’t need to buy new filters, just clean out the one you have.

To you as a prepper, these are a great addition to any survival supply. There is not a lot of instruction to give on these. You put one end in the water you want to filter and pump. The water that comes out is ready to drink. You can use this in combination with the bleach technique mentioned above but it’s really not required. I suggest every prepper have one of these in their bug out bag.

These filters will catch particles in your water down to 0.2 microns in size. Which means they should catch most trouble causing organisms in your water. Keep in mind that viruses are too small to catch with these filters (not much of a concern in remote areas). See the chart below for more info on the sizes of different micro-organisms.

Microorganisms and Their Sizes

Giardia, Cryptosporidium
Cholera, E. coli, Salmonella
Hepatitis A, rotavirus, Norwalk virus
5 microns or larger
0.2 – 0.5 microns
0.004 microns
Filter Type
Water filter
Water purifier
Particle Size Rating
1.0 – 4.0 microns
0.2 – 1.0 microns
Down to 0.004 microns

Purifying Water with Iodine

Using Iodine to disinfect water does not seem to be terribly popular but is a GREAT skill to know how to do. Iodine is a great wound disinfectant that is often found in first aid kits and is shelf stable! If it is not in your kit, it could be a great addition as it not only disinfects wounds but can also be used to treat water for drinking purposes.

You will want an iodine solution called “Iodine Tincture” with a 2% USP content. “USP” refers to the concentration of iodine that is in the solution. The 2% solution is the most commonly available.

To disinfect the water, add 5 to 10 drops of iodine per liter of water (or about 5 to 10 drops per 32 fl oz). Then let the water stand for at least 20 minutes.

Iodine is most effective in warm water. If the water is cold or suspected of having a high number of pathogens, allow the water to sit at least 30 minutes. Also, you can increase the iodine safely to no more than 10 drops of iodine per liter of water. Adjust the number of drops and the exact time you allow it to sit after treatment based in accordance with how clean the water source is.When you drink the water after treating it with iodine, you will notice the taste of iodine is still in the water. This is normal and generally considered safe. Although some people seem to be more tolerant to the taste of water than others. Many survivalists and preppers will also include powdered energy drink mixes along with their iodine so that it may be used as a means of hiding the taste of iodine in the treated water.

A few notes about treating drinking water with iodine: Iodine is sensitive to sunlight and should always be kept in a dark place and/or in a dark colored bottle. Also, avoid drinking iodine treated water if you are pregnant, allergic to iodine, have thyroid problems, are on lithum, or are a woman over 50 years of age. Some people allergic to shellfish have also shown an allergic response to iodine.

Remember that you can always do a combination of these methods if you are really worried about the quality of water. Such as treating the water chemically first, and then filtering the water.