Water Purification
Once you have your water, you need to purify it to make sure that it is
not contaminated with material that will cause sickness or death. The most
common contaminants are biological hazards, organic and inorganic toxins.
The most common methods of water purification are boiling, adding
disinfectants, and various types of filtering.
Most biological hazards consist of naturally occuring bacteria and other
organisms.
BIOLOGICAL HAZARDS
BOILING. Boiling water for one minute will kill all bacteria. However,
since additional various organisms that are harmful and commonly found in
water are not bacteria, 15 to 20 minutes of boiling is needed to kill these
other organisms to give you sterile water.
DISTILATION. Distilation is the most reliable method for obtaining pure
water as the resulting water is sterile, soft, nuetral in pH and removes
all other contaminates as well. If the distiller does not have some sort of
system that preheats the water to remove various gases, the various gases can
be collected in the distillate if all boiled off contaminants are not purged
by running steam through the condensor at the begining of the batch.
DISINFECTANTS. The most common disinfectant is chlorine. Chlorine is a
poisonous gas and hazardous to handle. Two safer forms of chlorine are common
household bleach which is a 5.25% solution of sodium hypoclorite, and dry pool
chorine ("burn out" or "shock treatment) which is 65% calcium hypoclorite. Dry
pool chlorine can be used to make a solution that is the same concerntration as
household bleach, 24.5 grams (about 10 Tablespoons) of powder in 1 gallon of
water. This mixing MUST be done in a very well ventilated area and stored in
an air tight enclosure since it gives off enough chlorine gas to cause
problems. Please note that many bleaches state, "not for human consumption."
If the listed ingrediants contains anything other than sodium hypochlorite,
avoid it. If it contains ONLY sodium hypochlorite, it is okay. For water
purification use hypochorite solution in the following mixes
Volume clear water cloudy water
1 Quart 2 drops 4 drops
1 Gallon 8 drops 16 drops
5 gallons 1/2 tsp. 1 tsp.
Allow at least 30 minutes for the chlorine to kill all microorganisms.
Tuberculosis organisms are the only organism that is resistant to chlorine.
Use a 1 to 10 solution for cleaning instruments and surfaces. Do NOT use
hypochlorite solutions for irrigating wounds (as was done in WW1) as the
hypochlorite dissolves blood clots.
Iodine is extremely toxic. One source of iodine are the solid crystals.
How to use iodine to sterilize water. Put 4-8 grams of iodine crystals in a
1 oz. glass jar (must have glass or bakelite stopper otherwise the iodine will
react with the plastic or metal stopper and destroy it.) Actually 0.1 gram is
adequate for the job, but using a larger amount of iodine creates a saturated
solution much quicker.
Put in 1 oz. (1 tablespoon or 3 teaspoons) of water (at least room
temperature, body temperature prefered).
Close stopper and shake for several minutes. You now have a saturated
solution. A saturated solution is when as much solid has disolved in a liquid
as it can.
Carefully pour off 10ml (10cc, 2 teaspoons) of the saturated solution.
REMEMBER, the iodine crystals are VERY TOXIC! The reason that adding more
water than needed is suggested is so that you need not tip the bottle over too
far thus spilling some crytals.
Add the 10ml (2 teaspoons) of saturated solution to 1 liter (1.06 quart) of
water.
Let stand at least 15 minutes at 77 degrees F. or higher. Make sure all
of the interior surface including lid get treated.
Another form of iodine is the familiar tincture of iodine which is 2%
iodine and 2% sodium iodide in alcohol. Use 3-5 drops of tincture per quart of
clear water and 10 drops of tincure in cloudy water. Please remember, very old
tincure or tincure that has been left unstoppered may have lost some of its
alcohol due to evaporation and whould have an excessive concentration of
iodine.
Betadines are not suitable for water purification. Betadine scrub should be
only used for cleaning intact skin as it is very toxic to tissues. Betadine
solution when diluted 1:100 (3 drops per ounce of water) is suitable for
cleaning wounds.
FILTERING. Only extremely sophisticated filters are precise enough to
remove micro organisms. One device that is able to do this is the Katadyn
family of water filters from Switzerland. It consists of a core of ceramic
material whose holes are so small that no living organism can pass through.
There are available synthetic woven filters for use in industry that are able
filter out micro-organisms. Example, Coors beer is pastuerized by the micro
filtration process.
INORGANIC HAZARDS
Toxic substances like arsenic, various heavy metals, aluminum, etc. are
a less common hazard. They can be found however in water near mining sites and
in areas that have alkaline lakes. A lack of normal plant growth around a
water source or unusually colored algae are frequently signs of abnormal pH or
unusual contamination.
Many of these toxins are only water soluable if the water has an unusual pH
factor. That is these factors can only be in solution in the water if the
water is fairly acidic (low pH) or fairly alkaline (high pH). Totally neutral
pH is 7 and most water sources will be between 5 and 8 in pH. If you have the
papers to measure pH and add lyes or acids to the water to bring the pH within
a normal range, the metal may go out of solution and become a solid, but in
particles that are so small that they stay suspended in the water. Letting the
water set overnight will allow the particles to drop to the bottem, but since
they are so small pouring the water from the container might be enough to put
them back in suspension again. A better method would be to filter the
neutralized water. A microfiltration filter could be used for this, but even
common laboratory filter papers would remove most of the precipitated solids,
even though common filter paper is not fine enough to filter out biological
hazards. Many inorganics are highly reactive and are adsorbed by dirt or
activated carbon filters.
Some inorganic hazards like asbestos fibers are mechanically hazardous, any
filtration method will remove this items. If no filters are available, just
letting the water stand still for several hours or overnight with help reduce
contamination. Siphoning water off of the top of standing water is the best way
to remove the water as pouring the container will kick up the sediment again.
A NOTE ON LABORATORY FILTER PAPERS
These filters should be used to prefilter any water that you are going to
treat. They aren't suitable for an entire process, but their removal of
larger contaminants improves preformance of disinfectants and extends the
working life of microfiltration units. Filter papers come in various speeds.
The faster the speed of the paper, the less that is filtered out. Filter
papers are very inexpensive, lightwieght and compact. For maximum effect you
can prefilter water through a fast filter and then put that water through a
slow filter.
ORGANIC HAZARDS
These substances can be removed via activated carbon filters. An item to
note about activated carbon filters: water or moisture in the carbon filters
is a breeding ground for biological organisms. Many filters are doped with
silver compounds to prevent or retard organism growth.
SOIL FILTERS
The book NUCLEAR WAR SURVIVAL SKILLS, in addition to having good information
on water storage and transporation, has an excellent design for a water filter
based on a bucket, gravel, towels and dirt.