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Emergency
Disinfection of Drinking Water
After
a major storm, or disaster you have to assume
that all water sources have been contaminated,
until you have been informed otherwise.
After a disaster, you should only used
bottled water or purify all water for drinking,
cooking, brushing your teeth, and for cooking,
eating, and washing utensils.
You should also use purified water for
washing your hands, body and kitchen and
bathroom surfaces.
The
two common disease-causing microorganisms often
found in floodwaters are Giardia lamblia and
Cryptosporidium. These microorganisms are often found in rivers and lakes.
1.
Giardia can cause diarrhea, fatigue, and
cramps after ingestion.
2.
Cryptosporidium can cause diarrhea,
nausea and/or stomach cramps.
Individuals with weakened immune
systems, such as the very old and very young
and Individuals with weakened immune systems,
such as children and the elderly are likely to
have more severe and more persistent symptoms.
When
disinfecting or purifying water, do not use dark color water, or water that has an odor, or contains
floating material.
One
method of disinfecting water is to boil it for
10 minutes at a rolling boil.
Water that has been boiled usually has a
flat taste.
To improve the taste, you can aerate the
water by pouring it back and forth from one
clean container to another, and then allow the
water to stand for a several hours.
You can also add a pinch (1/8 teaspoon)
of salt for each quart or liter of water
boiled.
There
are times when boiling water is not possible,
for these times, chemical disinfection should
be used. Chlorine and iodine are the two chemical agents that are
often used to treat water.
Chlorine and iodine are slightly
effective in controlling Giardia, with chlorine
being more effective.
However, chlorine and iodine may not be
effective in controlling Cryptosporidium, as it
is a more resistant organism.
Both Chlorine and iodine work best in
warm water.
When
using bleach, you want to add eight drops of
liquid chlorine bleach (such as Clorox) per
gallon of water. Use only bleach that contains 4 to 6 % sodium hypochlorite.
Do not use scented bleach or bleach that
contains other additives as these could cause
you physical harm or even death.
Household
chlorine bleaches usually contains 5.25%
available chlorine and most will have a
procedure written on the label for treating
water. However,
when the procedure is not given, then locate
the percentage of available chlorine on the
label and follow the table below as a guide for
how much bleach to add per liter of filtered
water.
(1/8
teaspoon = 8 drops)
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Available Chlorine
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Drops per
Quart/Gallon of Clear Water
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Drops per Liter of
Clear Water
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1%
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10 per quart
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40 per Gallon 10 per
Liter
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4-6%
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2 per Quart
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8 per Gallon (1/8
tsp) 2 per liter
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7-105
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1 per Quart
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4 per Gallon 1 per
Liter
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If
you do not know the strength of the bleach,
then add ten drops per quart or liter of
filtered and settled water.
If the water is cloudy, colored, or
murky, then double the amount of chlorine.
DO
NOT USE NON-CHLORINE BLEACH TO DISINFECT WATER!
Thoroughly
mix the treated water and then permit it to
stand, covered, for approximately 30 minutes or
longer. The
treated water should have a slight chlorine
odor, if it does not, then the process should
be repeated.
Allow the water to stand for an
additional 15 minutes longer.
If the taste of chlorine is too strong
then allow the treated water to stand exposed
to the air for a several hours, and then aerate
the water by pouring it back and forth from one
clean container to another.
Chlorine
tablets can also be used to disinfect filtered
and settled water.
Chlorine tablets can usually be
purchased from drug and sporting goods stores.
When using chlorine tablets, make sure
to carefully read and follow the directions on
the packaging label.
If the container or packaging does not
contain instructions for disinfecting drinking
water, then use one tablet for each quart or
liter of water to be purified.
How
to use Tincture of Iodine to Disinfect Filtered
and Settled Water:
Tincture
of Iodine is commonly found in nearly every
medicine chest or first aid kit and can be used
to disinfect water.
Add 20 drops of 2 percent iodine per
gallon of clear water or 40 drops per gallon of
cloudy water.
Iodine
tablets can also be used to disinfect filtered
and settled water.
Iodine tablets can also be used to
disinfect filtered and settled water and can
usually be purchased from drug and sporting
goods stores.
When using Iodine tablets, make sure to
carefully read and follow the directions on the
packaging label.
If the container or packaging does not
contain instructions for disinfecting drinking
water, then use one tablet for each quart or
liter of filtered and settled water.
Water
in water pipes and toilet flush tanks (not
bowls) is safe to drink if the valve on the
main water line was closed before the flood.
If
your water comes from a well that has been
contaminated with floodwater, you should
continue to disinfect your water even after the
floodwaters recede until you have your well
tested and the test reveal no contamination.
As soon the floodwaters recede or as
soon as you suspect that your well may be
contaminated, immediately contact your local or
state health department or agriculture
extension agent for specific advice.
**ONLY
USE WATER THAT HAS BEEN PROPERLY DISINFECTED
FOR DRINKING, COOKING, MAKING ANY PREPARED
DRINK, OR FOR BRUSHING TEETH.
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