3 pp.This publication explains how to disinfect water after a flood, as well as where to find water in an emergency when supplies are limited

Dozier, Monty

Schoessow, Courtney

Texas A&M University

ER-002 
6-06
Monty C. Dozier, Assistant Professor and Extension 
Water Resources Specialist 
Courtney J. Schoessow, Extension Program Specialist—Health 
The Texas A&M University System
After a disaster such as a hurricane or flood, your water supplies may have 
become contaminated or been temporarily cut off. To make sure your wa-
ter is safe, follow these guidelines: 
Listen to and follow public announcements from your local authorities. 
They will tell you if your tap water is safe to drink or use for cooking and 
bathing. 
If the water is unsafe, use only bottled water, or boil or disinfect your 
water for cooking, cleaning or bathing. 
Until your water supply is tested and found to be safe, use only bottled, 
boiled or treated water for drinking, cooking, washing dishes, cleaning, 
brushing your teeth, washing your hands and bathing. 
If water is limited, use an alcohol-based hand sanitizer to wash your 
hands.
How to disinfect water 
Boiling water is the best way to kill harmful organisms that can make you 
and your family sick. Use clean containers (where possible) and follow 
these steps to creating safe drinking water: 
Strain the water through a clean cloth, coffee filter or paper towel into a 
container to remove any sediment or floating matter.
Boil the water vigorously for at least 1 minute.
After it cools, the water is ready to use. To improve the taste, you may add 
a pinch of salt to each quart of boiled water, or pour the water back and 
forth from one clean container to another several times.
Using chemicals
If it is not possible to boil the water, strain it as in listed in Step 1 above, 
then disinfect it with bleach or iodine, whichever is available:
Disinfecting Water 
after a Disaster
Liquid chlorine bleach (from the home laundry 
or grocery store). Use common, unscented house-
hold laundry bleach. Read the product label to 
find percentage of chlorine and use this table to 
determine how much bleach to add to the water:
•	Add bleach to the water and stir or shake the 
container thoroughly.
•	Let the water stand for 30 minutes. If you can 
smell a slight chlorine odor, the water should 
be safe.
•	 If you cannot smell a slight chlorine odor, re-
peat the dosage and let the water stand for 15 
more minutes before using it.
Tincture of iodine (from a medicine chest or first 
aid kit). 
•	 For clear water, add 5 drops of iodine per quart 
of water. If the water is cloudy, add 10 drops of 
iodine per quart of water.
•	Let the mixture stand for 30 minutes, after 
which water should be safe to use.
Private water supplies
If you have your own water supply, such as a well, 
cistern, spring or other private source, ask your 
health department or Texas Cooperative Exten-
sion office to inspect it for sanitary quality and to 
show you how to keep it safe. 
You should also have your water tested for dis-
ease-causing bacteria such as E. coli or total or fe-
cal coliforms. These and other bacteria can cause 
many diseases in people. 
Under normal conditions if your water system is 
properly built and maintained, you can be con-
fident that your water is safe to drink. However, 
under emergency or disaster conditions, particu-
larly during floods, these sources may become 
dangerous to use. Unless you are assured oth-
erwise by test results, you should presume that 
during a disaster, no water is safe, and disinfect 
all water during such emergencies.
Emergency sources of water
If water is hard to find, try:
Water sources in and around your home
•	Water heaters: Turn off the power that heats 
the tank and let the tank cool. Place a contain-
er under the tank and open the drain valve at 
the bottom. Don’t turn the tank back on until 
utility services are restored. 
•	Toilet tank: The water in the tank (not the 
bowl) is safe to drink unless chemical treat-
ments have been added. 
•	Water pipes: Release the air pressure into the 
plumbing system by turning on the faucet at 
the highest point in the house. Then drain the 
water from the lowest faucet. 
•	Outside: Rainwater and water from coiled gar-
den hoses can be used after it is disinfected. 
Other water sources 
If you must use an emergency water source, you 
can consider underground water, such as that 
obtained from wells or springs, or surface water, 
such as from a creek or lake. Underground wa-
ter is less likely to contain contamination harm-
ful to your health than is than water from surface 
sources. 
However, if underground water is unavailable, 
you may use surface water from a creek, river, 
lake or pond, in that order. If possible, obtain 
surface water upstream from inhabited areas and 
dip it from below the surface
Avoid water that has a dark color, emits an odor 
or contains floating materials; these characteris-
tics may indicate that the water is polluted. 
Remember: When you are unsure of its quality, 
disinfect all water before consuming it. 
Do not disinfect or drink water when it:
•	 Is dark in color
•	Has an odor 
•	Contains floating material
•	Contains chemicals from a spill such as oil or 
gas
Storing water in containers
Store disinfected water in clean, sanitary glass 
or plastic containers. Plastic containers are good 
because they are lightweight and unbreakable. 
Available chlorine
Drops to be added per quart
Clear water Cloudy water
1 percent 10 20
4 to 6 percent 2 4
7 to 10 percent 1 2
Don’t use metal containers because they may 
corrode and give the water an unpleasant taste. 
How much water do I need 
to drink each day?
Because water is so important to human survival, 
never ration it. Drink at least 2 quarts per day as 
long as supplies last. 
This information was excerpted and adapted from resources from the University of Idaho, 
the University of Missouri, the University of Tennessee Institute of Agriculture and from 
http://www.fema.gov/rrr/waterf.shtm, http://www.bt.cdc.gov/disasters/foodwater.asp, 
and http://www.lsuagcenter.com/en/family_home/hazards_and_threats/ 
publications/be+safe+stay+healthy+after+a+disaster.htm.
Produced by AgriLife Communications and Marketing, The Texas A&M System
Extension publications can be found on the Web at: http://AgriLifebookstore.org
Visit the Texas AgriLife Extension Service at http://AgriLifeextension.tamu.edu
Educational programs of the Texas AgriLife Extension Service are open to all people without regard to race, color, sex, disability, religion, age, or national origin.
Issued in furtherance of Cooperative Extension Work in Agriculture and Home Economics, Acts of Congress of May 8, 1914, as amended, and June 30, 1914, in 
cooperation with the United States Department of Agriculture. Edward G. Smith, Director, Texas AgriLife Extension Service, The Texas A&M System.


English

Disinfecting Water after a Disaster

Texas A&amp;M Repository

ER-002 6-06Monty C. Dozier, Assistant Professor and Extension Water Resources Specialist Courtney J. Schoessow, Extension Program Specialist—Health The Texas A&M University SystemAfter a disaster such as a hurricane or flood, your water supplies may have become contaminated or been temporarily cut off. To make sure your wa-ter is safe, follow these guidelines: Listen to and follow public announcements from your local authorities. They will tell you if your tap water is safe to drink or use for cooking and bathing. If the water is unsafe, use only bottled water, or boil or disinfect your water for cooking, cleaning or bathing. Until your water supply is tested and found to be safe, use only bottled, boiled or treated water for drinking, cooking, washing dishes, cleaning, brushing your teeth, washing your hands and bathing. If water is limited, use an alcohol-based hand sanitizer to wash your hands.How to disinfect water Boiling water is the best way to kill harmful organisms that can make you and your family sick. Use clean containers (where possible) and follow these steps to creating safe drinking water: Strain the water through a clean cloth, coffee filter or paper towel into a container to remove any sediment or floating matter.Boil the water vigorously for at least 1 minute.After it cools, the water is ready to use. To improve the taste, you may add a pinch of salt to each quart of boiled water, or pour the water back and forth from one clean container to another several times.Using chemicalsIf it is not possible to boil the water, strain it as in listed in Step 1 above, then disinfect it with bleach or iodine, whichever is available:Disinfecting Water after a DisasterLiquid chlorine bleach (from the home laundry or grocery store). Use common, unscented house-hold laundry bleach. Read the product label to find percentage of chlorine and use this table to determine how much bleach to add to the water:•	Add bleach to the water and stir or shake the container thoroughly.•	Let the water stand for 30 minutes. If you can smell a slight chlorine odor, the water should be safe.•	 If you cannot smell a slight chlorine odor, re-peat the dosage and let the water stand for 15 more minutes before using it.Tincture of iodine (from a medicine chest or first aid kit). •	 For clear water, add 5 drops of iodine per quart of water. If the water is cloudy, add 10 drops of iodine per quart of water.•	Let the mixture stand for 30 minutes, after which water should be safe to use.Private water suppliesIf you have your own water supply, such as a well, cistern, spring or other private source, ask your health department or Texas Cooperative Exten-sion office to inspect it for sanitary quality and to show you how to keep it safe. You should also have your water tested for dis-ease-causing bacteria such as E. coli or total or fe-cal coliforms. These and other bacteria can cause many diseases in people. Under normal conditions if your water system is properly built and maintained, you can be con-fident that your water is safe to drink. However, under emergency or disaster conditions, particu-larly during floods, these sources may become dangerous to use. Unless you are assured oth-erwise by test results, you should presume that during a disaster, no water is safe, and disinfect all water during such emergencies.Emergency sources of waterIf water is hard to find, try:Water sources in and around your home•	Water heaters: Turn off the power that heats the tank and let the tank cool. Place a contain-er under the tank and open the drain valve at the bottom. Don’t turn the tank back on until utility services are restored. •	Toilet tank: The water in the tank (not the bowl) is safe to drink unless chemical treat-ments have been added. •	Water pipes: Release the air pressure into the plumbing system by turning on the faucet at the highest point in the house. Then drain the water from the lowest faucet. •	Outside: Rainwater and water from coiled gar-den hoses can be used after it is disinfected. Other water sources If you must use an emergency water source, you can consider underground water, such as that obtained from wells or springs, or surface water, such as from a creek or lake. Underground wa-ter is less likely to contain contamination harm-ful to your health than is than water from surface sources. However, if underground water is unavailable, you may use surface water from a creek, river, lake or pond, in that order. If possible, obtain surface water upstream from inhabited areas and dip it from below the surfaceAvoid water that has a dark color, emits an odor or contains floating materials; these characteris-tics may indicate that the water is polluted. Remember: When you are unsure of its quality, disinfect all water before consuming it. Do not disinfect or drink water when it:•	 Is dark in color•	Has an odor •	Contains floating material•	Contains chemicals from a spill such as oil or gasStoring water in containersStore disinfected water in clean, sanitary glass or plastic containers. Plastic containers are good because they are lightweight and unbreakable. Available chlorineDrops to be added per quartClear water Cloudy water1 percent 10 204 to 6 percent 2 47 to 10 percent 1 2Don’t use metal containers because they may corrode and give the water an unpleasant taste. How much water do I need to drink each day?Because water is so important to human survival, never ration it. Drink at least 2 quarts per day as long as supplies last. This information was excerpted and adapted from resources from the University of Idaho, the University of Missouri, the University of Tennessee Institute of Agriculture and from http://www.fema.gov/rrr/waterf.shtm, http://www.bt.cdc.gov/disasters/foodwater.asp, and http://www.lsuagcenter.com/en/family_home/hazards_and_threats/ publications/be+safe+stay+healthy+after+a+disaster.htm.Produced by AgriLife Communications and Marketing, The Texas A&M SystemExtension publications can be found on the Web at: http://AgriLifebookstore.orgVisit the Texas AgriLife Extension Service at http://AgriLifeextension.tamu.eduEducational programs of the Texas AgriLife Extension Service are open to all people without regard to race, color, sex, disability, religion, age, or national origin.Issued in furtherance of Cooperative Extension Work in Agriculture and Home Economics, Acts of Congress of May 8, 1914, as amended, and June 30, 1914, in cooperation with the United States Department of Agriculture. Edward G. Smith, Director, Texas AgriLife Extension Service, The Texas A&M System.

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Disinfecting Water after a Disaster

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Disinfecting Water after a Disaster

Abstract

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Texas A&M University

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