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Emergency Water Purification
Sanitation of water during an emergency

Regardless of the climate zone, a human needs to meet a certain level of water intake daily. Without proper fluid intake the body begins to show symptoms of dehydration. Symptom start with headaches, weakness and dizziness.

However drinking untreated water can further increase water loss. Water borne diseases such as dysentery, typhoid, and cholera are just a few of the problems we have to deal with. For this reason, it is a good idea to expand your knowledge of water purification methods. Fit the scope of this article we will water purification methods using supplies found in a home and a few items that can be purchased for an emergency. Hurricane Katrina and now more recently the water crisis in Toledo will hopefully bring attention to the importance of emergency water purification methods.

We have several articles covering the importance of proper hydration in several articles. You can find more information at the bottom of the article.

Usually the best methods to purify water are boiling and distillation. The methods covered on this article are for educational purpose only. It is not to be considered medical advice so please do your own research. We are covering purification methods that could be used in an event where a heat source may not be available. A water distiller can be built using common items such as a pressure cooker or tea pot. We will cover distillers in a separate article.

Note: It is very important to remove sediment from the water by filtering. Parasites and bacteria carried inside the solid (soil) particles are harder to destroy. Any time a chemical is used, the mix should be allowed sit for at least thirty minutes.

Water collection

Urban emergency water collection usually differs from wilderness survival methods. However, if we look around, there are still plenty of water sources. First, we must choose our water source wisely. We should try to collect from a water source is free of chemicals. During hurricane Katrina, the water supplies were contaminated with harmful sewage-related bacteria and toxic chemicals. During most urban situations, harmful toxins and chemicals will likely be found in the water supply. Second, we need to remove sediment or particles from the water. Third step is to properly treat the water to make it safe for consumption.

Important: The problem with urban water supplies is the possibility of chemical contamination. It is important that we keep this in mind when gathering water. Their potential toxic effects can cause adverse health defects on humans and animals. Its crucial to avoid long term exposure to these bioaccumulative toxins. Catching rain water is a good way to avoid harmful chemicals. This can be done with rain barrels, tarpaulins (tarps), and containers. Depending on the filter micron rating some of the chemicals can be removed. A micron rating for a water filter is an attempt to quantify the ability of the filter to remove contaminants of a particular size. The physical pore size traps larger particles as they pass through the ceramic filter hopefully removing the harmful pathogens. Below we provide a sample chart.

Some contaminants and their size in microns:

Contaminant size
Contaminant Size
Giardia lamblia
8 to 12 microns
Cryptosporidium parvum
4 to 6 microns
Bacteria (salmonella - E.coli
0.2 to 4 microns
0.004 to 0.1 microns

This list does not include harmful chemicals such as Herbicides, Pesticides, Car fluids (oil,glycol,diesel), Metals, Rodenticides etc. All of which pose health risks to humans.

So what are some of our choices for water purification during an emergency? How we will purify the water depending on how much pre-planning has been done. Some people purchase water filtration systems before being faced with an emergency. Filtration is defined as a physical process that occurs when liquids, gases, dissolved or suspended matter adhere to the surface of, or in the pores of, an absorbent medium. If a water filtration system is unavailable, don't worry we will discuss possible methods of treatment.

CDC Water Treatment Methods for the Backcountry and Travel

Purification Methods

Filtration - Makeshift Water Filters

With the use of sand, charcoal, cloth and other materials some of the contaminants can be removed. Should be followed by boiling or chemical treatment.


1.the volatilization or evaporation and subsequent condensation of a liquid, as when water is boiled in a retort and the steam is condensed in a cool receiver.
2. the purification or concentration of a substance, the obtaining of the essence or volatile properties contained in it, or the separation of one substance from another, by such a process.


Boiling is the surest method to make water safe to drink and kill disease-causing microorganisms like Giardia lamblia and Cryptosporidium, which are frequently found in rivers and lakes.
These disease-causing organisms are less likely to occur in well water (as long as it has not been affected by flood waters). If not treated properly and neutralized, Giardia may cause diarrhea, fatigue, and cramps after ingestion. Cryptosporidium is highly resistant to disinfection. It may cause diarrhea, nausea and/or stomach cramps. People with severely weakened immune systems are likely to have more severe and more persistent symptoms than healthy individuals. Boil filtered and settled water vigorously for one minute (at altitudes above one mile, boil for three minutes). To improve the flat taste of boiled water, aerate it by pouring it back and forth from one container to another and allow it to stand for a few hours, or add a pinch of salt for each quart or liter of water boiled.

If boiling is not possible, chemical disinfection of filtered and settled water collected from a well, spring, river, or other surface water body will still provide some health benefits and is better than no treatment at all.


Boiling will not remove or neutralize common chemicals or metals. If the water is contaminated with chemicals (pesticides, petroleum, glycol) then distillation would be an alternative.

One of the most effective methods of using boiling to purify water is Distillation

  • Distillation Systems use a process of heating water to the boiling point and then collecting the water vapor as it condenses, leaving many of the contaminants behind
  • Distillation Systems have a very high effectiveness in removing protozoa (for example, Cryptosporidium, Giardia)
  • Distillation Systems have a very high effectiveness in removing bacteria (for example, Campylobacter, Salmonella, Shigella, E. coli)
  • Distillation Systems have a very high effectiveness in removing viruses (for example, Enteric, Hepatitis A, Norovirus, Rotavirus)
  • Distillation Systems will remove common chemical contaminants, including arsenic, barium, cadmium, chromium, lead, nitrate, sodium, sulfate, and many organic chemicals
  • Source:

Common Chemicals

This includes Flocculation by using military Chlor Floc, Chlorine Dioxide, Iodine, Chlorine, Calcium Hypochlorite, and Potassium Permanganate

Click each item for more information:

  • Chlor Floc
  • Chlorine Dioxide (Potable Aqua, Aquamira)
  • Iodine (Potable Aqua, Coghlans, Polar Pure Plus,)
  • Calcium Hypochlorite
  • Potassium Permanganate

  • Manufactured Filters - ceramic filters or Makeshift filters

    Manufacturers such as Katadyn and Berkley manufacture long term water purifiers. There are also companies that sell the ceramic filter element. Understanding contaminant size and different levels of filtration determined by the filter hole size is important.


    A microfiltration filter has a pore size of approximately 0.1 micron (pore size ranges vary from 0.05 micron to 5 micron)

    • Microfiltration has a very high effectiveness in removing protozoa (for example, Cryptosporidium, Giardia)
    • Microfiltration has a moderate effectiveness in removing bacteria (for example, Campylobacter, Salmonella, Shigella, E. coli)
    • Microfiltration is not effective in removing viruses (for example, Enteric, Hepatitis A, Norovirus, Rotavirus)
    • Microfiltration is not effective in removing chemicals


    A ultrafiltration filter has a pore size of approximately 0.01 micron (pore size ranges vary by filter from 0.001 micron to 0.05 micron.

    • Ultrafiltration filters remove particles based on size, weight, and charge
    • Ultrafiltration has a very high effectiveness in removing protozoa (for example, Cryptosporidium, Giardia)
    • Ultrafiltration has a very high effectiveness in removing bacteria (for example, Campylobacter, Salmonella, Shigella, E. coli)
    • Ultrafiltration has a moderate effectiveness in removing viruses (for example, Enteric, Hepatitis A, Norovirus, Rotavirus)
    • Ultrafiltration has a low effectiveness in removing chemicals

    Makeshift water filters

    Water filters can filter and purify water using different methods.

    * Ceramic filters
    * Chemical treatment
    * Systems that use both

    Ceramic filters

    Built of porous ceramic material, the ceramic filters remove bacteria by capturing the contaminants down to 0.2 micron range. It seems that EPA recommended filter pore size is one micron absolute. By using a pore size smaller than the viruses, bacteria or sediment, the water passes through the filter while the impurities are captured by the filter. Some bacteria and viruses will get past the filter, so it is still a good idea to boil or treat the water.

    Chemical treatment

    Water is often treated with chemicals such as iodine or chlorine in an attempt to kill the harmful bacteria or viruses. Some filters include a chemical treatment stage such as paper treated with iodine. Charcoal is often used to improve the taste of the water.

    Water procurement in an urban survival situation such as an earthquake or hurricane can be tricky. The water can be contaminated with human waste, toxic chemicals, and pathogens.

    We decided to build a filter that could be put together with items from a hardware store or even your backyard. Filters can be built using drink bottles, aluminum cans, and coffee cans.

    Items used to build emergency filter:

    * Sand
    * Charcoal
    * Sphagnum (peat moss)
    * Cloth
    * Moss
    * Ultraviolet light
    * Stones

    Attempting to make a multistage filter we used sphagnum. After reading several sources claiming that sphagnum would release iodine into the water, we decided to give it the practicalsurvivor trial.

    Iodine test

    To properly treat water with iodine a level of 8 PPM (parts per million) is recommended. If the water has heavy sediment, the level would have to increase from 8 PPM to 16 PPM. Water is then allowed to sit for 10 minutes for full treatment.

    Test 1 - First we want confirm that sphagnum will release iodine. Using iodine test strips we pour ten ounces of distilled water into a bowl. We drop the test strip into the water and leave it for 30 seconds. Iodine levels were not present.

    We follow up by adding peat moss purchased at a department store. We tested with the sphagnum in the water and after removing it. The iodine test strips are color based so our concern was that the tint of the sphagnum would alter our test results.

    Results Test 1 - 1.0 PPM after 30 seconds of exposure to the peat moss. Although 1 PPM is not enough to properly treat water, removing sediment from the water coupled with low level iodine should help to rid the water of some of the contaminants.

    Test 2 - For our second trial, we built a multistage filter using a 2 liter soda bottle.

    Filter stages:

    1) Base layer closest to the mouth of the bottle - Green moss
    2) Sphagnum
    3) Charcoal and Peat moss mixture
    4) Stones

    Instead of allowing the water to simply go through the filter, we wanted to increase contact time with the sphagnum in hopes to increase iodine levels. The stages are set up to help remove sediment and possibly some of the parasite. Charcoal is used to improve the smell and taste of the water. Charcoal can also help remove some of the and bacteria.

    Results Test 2 - Iodine Level 1 PPM. Increasing the contact time with the peat moss did not increase the level of iodine. Increasing the treatment time is part of the treatment.

    All the testing was done with sphagnum purchased at a store. Testing with sphagnum moss from a peat bog might show a higher level of iodine.

    Treatment with iodine from iodine crystals will get the proper iodine levels of 8 PPM. The chemical strips measure up to 5 PPM. This is a sample after only seconds of contact:

    Chemical Water Purification

    Using household items:

      Potassium permanganate
      Iodine tincture
      Bleach, Calcium Hypochlorite
      Hydrogen Peroxide

    Potassium Permanganate - (Condy's Crystals) can be purchased online or at hardware stores. Potassium Permanganate is sold as a water softener. Can be purchased in both powder and pill form (permitabs). This chemical compound has many uses from fire starting to water purification. Just a few crystals can treat a quart of water.

    ( aproximately 0.01% solution) 1 gram per liter (3 - 4 crystals) is suggested by some sources but EPA recommendations are recommended.

    20 mg/L with a 24 hour contact time for bacteria
    50 mg/L with a 2 hour contact time for viruses

    Iodine tincture - Around eight drops per liter or about thirty per gallon

    Bleach - Two drops of bleach per quart 1/8 teaspoon (or eight drops) of regular, unscented, liquid household bleach for each gallon of water. Note: Be mindful that household bleach degrades over time.

    As per EPA suggestions:

    Water purification by Bleach
    Available Bleach Drops per Quart/Gallon of Clear Water Drops per Liter of Clear Water
    10 per Quart - 40 per Gallon
    10 per Liter
    2 per Quart - 8 per Gallon (1/8 teaspoon)
    2 per Liter
    1 per Quart - 4 per Gallon
    1 per Liter

    Hydrogen peroxide - (untested) During research we found recommended thirty-five to fifty percent concentration being used.

    Manufactured Filter Systems

    There are several manufacturers that make water filters for the home. Although a personal unit could be used as a last resort, it may not be sufficient for a family. Larger models usually cost in the range of two hundred dollars or more. Katadyn makes a nice gravity microfiltration system named the Katadyn TRK Drip Gravidyn Water Filter

    emergency water filtration

    To view details Click Here Katadyn TRK Drip Gravidyn Water Filter

    A few other filters to take a look at in the 0.2 micron to 0.5 micron range are:

    Click the filter name for more information:

    During our research we also found a great filter from Simply Water company. We were able to build a long lasting (up to eight month) water filtration system for under fifty dollars. The system is built using two buckets or trash cans. With the proper tools the build time was under 10 minutes.

    Note: A lot of people contacted us asking for the link to purchase the filter.
    To purchase the filter Click Here

    Parts List

  • 1 Ceramic Filter Kit - pre-filter sock and a spigot included
  • 2 Five Gallon Buckets
  • Drill
  • 1/2"Drill Bit

  • Note: Set of 2 filters

    The kit consists of one ceramic filter, pre-filter sock and a spigot. The appropriate nuts and washers are included with the kit.

    The ceramic filter has a filtration efficiency is 0.5 micron (Note: March 2011, the filter hole size was reduced from 0.5 to 0.2 micron) and has been tested for removal capabilities of contaminants such as Cryptosporidium, E. Coli, Vibrio Cholerae and will also help remove chemicals and poisons such as Arsenic, Pesticides, Lead and Aluminum. A filter such as this one would have been an excellent source of water during hurricane Katrina.

    Filter performance:

    • Flow rate / Up to 1 gallon of clean water per hour (gravity flow)
    • Filter will accept water from floods, lake, rain, well, tap, river or stream
    • Cleansable with clean damp cloth
    • Once in use, filter will last 6-8 months

    Filter construction was simple. We used a 1/2" drill bit to make three holes. The spigot hole needs to be a little larger than half inch. One hole is drilled at the bottom of the clean water bucket (blue bucket), one hole on the lid of the clean water bucket and one hole at the bottom of the unclean water bucket. More details on this video:

    We used a blue bucket as our clean water bucket and a white bucket for the contaminated water. (for illustration purposes) The spigot allows us to access the clean water without having to open the system. Note: Test the unclean water bucket for leaks before using the system. We would not want the contaminated water to drip into our clean water supply.

    The lid on the clean water bucket will need a hole to allow the water to drip down.

    The top bucket (white unclean water) bucket will need a hole at the bottom center. This will allow us to push the filter through and for the water to work its way through the ceramic filter.

    We installed the pre-filter sock to protect the filter during installation. It would be a good idea to use a piece of cloth to help filter some of the sediment out of the water if possible This should help ensure longer filter life. The filter can be cleaned using a damp cloth.

    Removal Capabilities

    Removal capabilities as follows:

    • 99% Arsenic 5 and 99% Arsenic 3 (special order)
    • 99% Hydrogen Sulfide (H2S)
    • 95% Chlorine and Chloramines
    • 98% Aluminum
    • 96% Iron
    • 98% Lead
    • 90% Pesticides
    • 85% Herbicides
    • 85% Insecticides
    • 90% Rodenticides
    • 95% Poly Aromatic Hydrocarbons
    • 99.999% of particles larger than 0.5 micron (Staffordshire University Labs)
    • 99.7% of particles larger than 0.3 micron (Staffordshire University Labs)
    • 98% of particles larger than 0.2 micron (Staffordshire University Labs)
    • 100% Giardia Lamblia
    • 100% Cyclospora
    • 100% removal of live Cryptosporidium (WRc Standard)
    • 100% removal of Cryptosporidium (NSF Standard 53 – A.C. fine dust)
    • 100% removal of E. Coli, Vibrio Cholerae (Johns Hopkins University)
    • 99.999% removal of Salmonella Typhil, Shigella Dysenteria, Kiebsiella Terrigena

    Other options

    Another option that seems to be popular is the Sawyers Point Zero Two Bucket System

    We hope to continue our testing of different filters and add to the page.

    Please see related articles:

    Methods such as chemical treatment, boiling, solar stills and distillation are covered in the articles below.

    Water Filtration on the Move

    Click title or picture for full article.

    Life Straw Water Filter

    Click title or picture for full article.

    Aquamira Frontier Pro

    Click title or picture for full article.

    Water Purification Methods

    Click title or picture for full article.

    Solar Still

    Click title or picture for full article.

    Perspiration / Vegetation Bags

    Click title or picture for full article.

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