Decontamination (Cont.)
Updated October 14, 2001



Below are water purifying methods for some toxins. There is wide variance in what works and what doesn't!

Boiling water for 20 minutes is also an acceptable method of water purification, but this is only reasonable for smaller quantities of water. This can present a few problems because the amount of water at the end of 20 minutes' boiling will be considerably less compared to the original amount.

While the standard method of water purification was and is chlorine, sometimes this product simply won't kill everything, as evidenced by the table below. This is the time for a filter.

Certain viral organisms are beyond minute, smaller than bacteria. The smallest bacteria is about the size of the largest virus. They range from 0.002 micron - 0.3 micron. About the only things less in size are herbicides, pesticides, synthetic dyes, metals and salts. So viruses require correspondingly minute filtering. The drawback is that filters for these extremely small particles clog in very short order. To remove every type of virus, you would need one that could filter down to .005. (See Reverse Osmosis chart.) Replacing filters this size, as needed, can get very expensive.

In order to extend the life of the smaller filter, we suggest using a pre-filter - one that removes particles larger than bacteria. This will put the largest load on the less refined filter and allow the smaller one to tackle anything that slips through. Filters that remove bacteria automatically cover the size of giardia cysts and cryptosporidium.

Stan has already checked into filters here and this very, very small size of .005 is not readily available. In fact, these fall into the category of medical grade. Locally, he could only find .5 filters which is 1000 times too big to remove every virus.

Surface filtration-pleated cartridge filters are a good choice. "Pleated cartridge filters typically act as absolute particle filters, using a flat sheet media, either a membrane or specially treated non-woven material, to trap particles. The media is pleated to increase usable surface area. Pleated membrane filters serve well as sub-micron particle or bacteria filters in the 0.1 to 1.0 micron range. Newer cartridges also perform in the ultrafiltration range: 0.005 to 0.15 micron."2

Sweetwater's Guardian Plus+ Purifier says it eliminates 99.9999+% bacteria, 99.9+% protozoan parasites and 99.9% waterborne viruses using both a 0.2-micron depth filter-Guardian filter and a 2.0- micron-ViralGuard cartridge. This does not address small viruses.

Even more high-end water purifiers like Katadyn Combi Water Filter removes bacteria, protozoa, cysts and chemicals, but not viruses.

We're not picking on either of these companies. Stan and I have portable Sweetwater Guardian Plus units. Under normal circumstances these are terrific little purifiers, but we know they aren't effective against all viruses. If you're really concerned about water quality, it might be worth investing in reverse osmosis or
ultraviolet systems.


According to Osmonics, Inc. "RO can meet most water standards with a single-pass system and the highest standards with a double-pass system. RO rejects 99.9+% of viruses, bacteria and pyrogens. Pressure, on the order of 200 to 1,000 psig (13.8 to 68.9 bar), is the driving force of the RO purification process. It is much more energy efficient compared to heat-driven purification (distillation) and more efficient than the strong chemicals required for ion exchange. No energy-intensive phase change is required."3

You can read an impartial article about RO from North Dakota State University here.


How UV purification works:

Water enters the purifier’s chamber. Once inside, it is exposed to UV light. The UV lamp used for this type of germicidal disinfection produces light at a wavelength of 253.7 nanometers (2,537 Angstrom units). At this wavelength, UV light destroys up to 99.9% of all bacteria, protozoa, viruses, molds, algae and other microbes. This includes such waterborne diseases as: E.coli, hepatitis, cholera, dysentery, typhoid fever as well as many others. UV purifiers work best when the water temperature is between 35
oF - 110oF. Extreme cold or heat interferes with the purifier’s performance. One must also look for situations that inhibit UV light from penetrating the water. Turbidity -- the state of water when it is cloudy from having sediment stirred up – will interfere with the transmission of UV.

UV works on the following:

Microorganism Destruction Levels4

(Ultraviolet energy at 253.7 nm wavelength required for 99.9% destruction
of various microorganisms - in µwsec/cm squared)
Bacillus anthracis 8,700 Shigella dysentariae (dysentery) 4,200
Corynebacterium diphtheriae 6,500 Shigell flexneri (dysentery) 3,400
Dysentery bacilli (diarrhea) 4,200 Staphylococcus epidermidis 5,800
Escherichia coli (diarrhea) 7,000 Streptococcus faecaelis 10,000
Legionella pneumophilia 3,800 Vibro commo (cholera) 6,500
Mycobacterium tuberculosis 10,000 Bacteriophage (E. Coli) 6,500
Pseudomonas aeruginosa 3,900 Hepatitis 8,000
Salmonella (food poisoning) 10,000 Influenza 6,600
Salmonella paratyphi (enteric fever) 6,100 Poliovirus (poliomyelitis) 7,000
Salmonella typhosa (typhoid fever) 7,000 Baker's yeast 8,800


This seems to be one of the most popular methods of water treatment. Look over this table5 of doses and reactions times for various organisms and then read Ozone Out for Indoor Air Cleaners before jumping on the ozone train.

Typical Dosage
Reaction Times
Aspergillus Niger (black Mount) Destroyed by 1.5 to 2 mg/1
Bacillus Bacteria Destroyed by 0.2 mg/1 within 30 seconds
Bacillus Anthracis Ozone susceptible
Clostridium Bacteria Ozone susceptible
Clostridium Botulinum 0.4 to 0.5 mg/1
Diphtheria Destroyed by 1.5 to 2 mg/1
Eberth Bacillus (Typhus abdominalis) Destroyed by 1.5 to 2 mg/1
Echo Virus 29 After a contact time of 1 minute at 1 mg/1 of ozone, 99.999% killed.
Escheriachia Coli Destroyed by 0.2 mg/1 within 30 seconds
Encephalomyocarditis Virus Destroyed to zero level in less than 30 seconds with 0.1 to 0.8 mg/1
Enterovirus Virus Destroyed to zero level in less than 30 seconds with 0.1 to 0.8 mg/1
GDVII Virus Destroyed to zero level in less than 30 seconds with 0.1 to 0.8 mg/1
Herpes Virus Destroyed to zero level in less than 30 seconds with 0.1 to 0.8 mg/1
Influenza 0.4 to 0.5 mg/1
Klebs-Loffler Virus Destroyed by 1.5 to 2 mg/1
Poliomyelitis Virus Kills 99.999% with 0.3 to 0.4 mg/1 in 3 to 4 minutes
Proteus Bacteria Very Susceptible
Pseudomonal Bacteria Very Susceptible
Rhabdovirus Virus Destroyed to zero level in less than 30 seconds
Salmonella Bacteria Very Susceptible
Staphylococci Destroyed by 1.5 to 2 mg/1
Stomatitis Virus Destroyed to zero level in less than 30 seconds with 0.1 to 0.8 mg/1
Streptococcus Bacteria Destroyed by 0.2 mg/1 within 30 seconds

It seems no particular system gets rid of everything. Maybe the best solution is several methods in conjunction with each other, to ensure total purification.


If there is ANY chance food has become exposed, toss it. It's not worth the risk. The exception to this are canned goods. They can be successfully decontaminated by soaking them a 0.5% sodium hypochlorite (Clorox) solution. Rinse thoroughly since this solution can corrode metal.