The Collection
and Purification of Drinking Water
Rules
of survival dictate that shelter and water are the top two priorities in any
survival situation whether you are lost in the wilderness or because a natural
disaster destroyed your community or city's infrastructure. Shelter can be
subjective and in some cases, a person's clothes constitute shelter. Therefore,
water is your main priority when you find yourself stranded or lost in the
wilderness or in any situation where your water source is suspected of being
contaminated with bacteria, pathogens and parasites.
Water Sources
Fresh
surface water is any body of water on the earth's surface that is not
considered seawater. Sources of fresh surface water include lakes, ponds,
rivers and streams. These sources of water must be filtered and purified before
they are safe to consume. Ninety seven percent of the water found on the
earth's surface is saltwater.
Ground
water is any water that originates from beneath the surface such as aquifers,
natural springs and underground rivers and lakes. In years past people living
in the countryside usually obtained their drinking water from natural springs
or hand dug uncapped/open wells. In today's world there are very few if any
places on the earths surface that humankind or animals have not tread.
Animals
and humans along with insects and naturally occurring bacteria can and will
contaminate any water source if they have access to it. Surface water is
usually contaminated by ground runoff that contains, pesticides, herbicides,
animal and human waste, poorly designed well/spring houses, and poor sanitation
measures at the point of collection. Even though the water has been filtered
through layers of earth and rocks groundwater can be contaminated at the point
of use. To be safe, and if you have the means, you should filter and purify any
ground water source if it is to be used for drinking water.
Alternative
Water Sources
These
sources can be found in various setting to include urban and rural areas.
Alternative sources include swimming pools, hot tubs, public fountains,
backyard water features, rain barrels used to collect water from roof runoff
and cisterns that are filled from rainfall. These sources must be filtered and
purified before they are safe to drink.
Waterborne
Dangers
Bacteria and parasites that can be present in a
water source include Coliform Bacteria, which is not a single strain of
bacteria but a group that includes E. coli. These types of bacteria may
not affect all individuals the same depending on their immunity and the strain
of bacteria. Cryptosporidium
is a parasite that causes
cryptosporidiosis and Giardia
is another parasite that can be found in water. These are just a few that can
be found in virtually any untreated water source, also you will find cholera,
typhoid and hepatitis present in many untreated water sources.
Collection Filtration and Purification
Coffee
filters, sand, gravel or clean cotton cloths will remove debris, insects,
certain waterborne cysts that contain bacteria and sediment from water. You can
obtain sand/silt and gravel from riverbanks, lakeshores and small streams. Once
filtered the water can be boiled or chemically treated. Charcoal will remove
insects, odour, sediment, debris, pesticides, herbicides, fuels, waterborne
cysts and most solvents from the water.
You
can make a filtering device from an empty and clean food storage can or large
plastic bottle by placing one or several holes in the bottom and layering the
filtering medium in the can/bottle. If you must filter into a small opening
such as a canteen or water bottle just put one hole in the bottom to better
control the flow into a smaller opening. Fill the can or bottle with the
activated charcoal/cloth/sand/coffee filters and gravel. You can make your own
charcoal by burning hardwoods though, not as effective as commercially
purchased activated charcoal, it is nonetheless quite effective at filtering
out contaminates.
Note: Activated charcoal is processed in such a
way as to increase the naturally porous nature of the charcoal. Typically,
activated charcoal used for water filtration is made from coconut husks.
Pour
the contaminated water over the filtering medium and allow it to flow into a
vessel for boiling or a canteen/container for chemical purification. If you do
not have charcoal and have no means to make any, place a coffee filter, clean
cotton cloth, sand and gravel in the can. You must always attempt to filter
your water before boiling or chemically treating. Sediment, insects and debris
in the water will reduce the effectiveness of boiling and chemical treatments.
Purifying Water
by Boiling
Filter
the water as described in to a suitable vessel. Water must boil rapidly for at
least one minute. If you know or suspect your elevation is a mile/1.6km or more
above sea level boil for a minimum of three minutes. Boiling will reduce your
water volume so keep this in mind if you have a limited water source. To help
conserve your boiled water use clean cotton cloths to collect the steam from
the boiling water by placing a cloth over the container while boiling to
collect steam/evaporated water. Only purified/distilled water evaporates from
boiling water.
Tip: You can desalinate saltwater by
placing a clean cotton cloth over a boiling vessel of seawater to collect
steam. Steam or evaporated water is purified and safe to consume. Once the
cloth has absorbed the evaporated water simply, squeeze the cloth into a
suitable container for storage. This method is only to be used in emergencies
and is not to be considered a substitute for equipment specially designed to
make saltwater safe to drink.
Question: Why must you
boil water longer at higher altitudes? Air pressure is less at higher
altitudes, which means that water will boil at a lower temperature, so water at
a rolling/rapid boil at higher elevations is not the same temperature as a
rapid boil at sea level. Once you are at about 7,000 feet (1.3 miles or 2
Kilometres) above sea level, for example, water boils at approximately 198ᵒF/
92.2ᵒC versus 212 Degrees or 100 degrees respectively at sea level. It is
important that water reaches and holds its temperature for a certain period to
ensure all bacteria, pathogens and parasites are destroyed. A one-minute rapid
boil at 212ᵒF/ 100ᵒC destroys all contaminates. To achieve the same effect at
198 or 92.2 degrees respectively the water must maintain its temperature for a
minimum of three minutes.
Tip: For every 500 feet/152.5 meters
above sea level, the boiling point of water is reduced by one degree.
Purify Water
Using 2% Liquid Iodine (Tincture of Iodine)
Ensure
the iodine has its own removable, built in dropper, or purchase one separately.
When chemically treating water you will need two water containers. One
container is used to collect the contaminated water, and once collected the
water must be filtered into a clean canteen or container by using the
previously described methods. The container used to dip contaminated water will
have contaminates around the drink line. Never drink from the container that was used
to collect contaminated water unless the container has been submerged between
one and three minutes in boiling water.
The
ratio is based on a one-quart/litre container. You will add five drops of
iodine per one-quart/litre of water. Once added seal and shake the container
well. You must wait 30 minutes before drinking to allow the iodine to work. If
the water temperature is below 68ᵒF/20ᵒC or if the water is cloudy after
filtering add five additional drops of iodine to the container and allow 60
minutes before drinking. Do not exceed 10 drops of iodine per one-quart/litre
of water.
Note: Some manufactures
of iodine tablets state in their directions that to purify the drink line,
canteen cap and surrounding cap threads you place the recommended number of
tablets in the container, seal, shake well, then loosen the cap and tilt the
container until water flushes over the cap threads/drink line and fills the
cap. You must then allow a minimum of 30 minutes before drinking. Use your own
best judgment when determining the safest way to purify the drink line/outer
surfaces of your water container.
Purify Water
Using Common Household Bleach That Contains 5% Percent Chlorine
Sodium
hypochlorite (liquid chlorine) is common household bleach. It typically has as
an active ingredient of between 5 and 6% chlorine. Read the active ingredient
carefully to ensure the bleach has adequate chlorine content. You must use
regular unscented bleach with no other additives. One gallon of bleach can
treat up to 3,800 gallons of water. Bleach that has been exposed to extreme
temperature variations becomes less effective. Bleach has a shelf life of
between four and six months. However, most bleach manufactures produce
household bleach with chlorine content between 5.25 and 7%, this allows for
some deterioration of the chlorine.
When
using bleach to purify water ensure you have a medicine dropper just for the
bleach. Never mix iodine and bleach, and more importantly, never mix the two to
purify water. The water must be filtered as described earlier and use the two-container
method when collecting contaminated water. The ratio is two drops of bleach per
one-quart/litre of water. Shake the container well and allow 30 minutes before
drinking. If the water is cold or extremely cloudy after filtering, add two more
drops for a total of four drops per quart/litre and wait an additional 30
minutes before drinking. Never exceed four drops per quart/litre. The water
will have a slight chlorine smell to it, if it has been properly treated. Use
vitamin C tablets (ascorbic acid) to enhance the flavour of chemically treated
water. Add flavour enhancers after the water has set for the recommended time
after treating.
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