Home Water Storage and Emergency Disinfection
Amount of Water to Store
The Department of Environmental Quality, Division of Drinking
Water recommends water storage of 1 gallon per person per day for 2 weeks. This
is based on 2 quarts or ½ gallon per person per day for drinking water and food
pre parathion, and another 2 quarts or ½ gallon per person per day for other
limited uses such as hand washing, teeth brushing and dishwashing. (This is a
total of 14 gallons per person for 2 weeks.)
A normally active person needs to drink at least 2 quarts
(1/2 gallon) of water each day. Hot environments and intense physical activity
can double that amount. Children, nursing mothers and people suffering from
disease or injury may need more water. Immune compromised people may want to
take extra precautions to minimize their risk in an emergency.
Supplies that are used for water purification and storage
- Food grade containers for storage of water
- Funnel
- Filters: coffee filters, clean cheesecloth, teal towel, or pillowcases
- Eyedropper
- Unscented chlorine bleach (5.25% sodium hypochlorite)
- Large clean pan with lid for boiling water
- If storing water in a 55 gallon drum, a pump is needed
- Purification device, back packer filters
- Camping stove to boil water
Storage Containers
Water should be stored in containers manufactured for food use.- A 5 gallon heavy duty plastic container with spigot to dispense water (weighs approximately 42 pounds when full).
- A 6 gallon Mylar water storage bag, impermeable to odor, gas and light, contained in a cardboard box for easy stacking. Durable (weights about 50 pounds).
- A 2 liter plastic drink container with screw on lid.
- A 55 gallon drum that has not stored toxic materials (weighs 460 pounds when full).
- A thermos type container.
- A 1 gallon size glass jug (padded with newspaper).
- Water “canned” in regular canning jars and processed for 20 minutes (repack in cardboard box and pad with newspapers).
Never use any containers that have held toxic substances
Plastic bleach bottles and gallon milk containers are generally manufactured with non-durable plastic that promotes biodegradability and is undesirable for long term water storage. Water stored in non-durable plastic containers may become toxic over time from breakdown products from the plastic container walls.
The disposable, plastic milk bottle is thin-walled and tends
to develop leaks easily. Liquid chlorine bleach bottles are made of thicker
polyethylene plastic and may be used for water storage if the empty bottles are
thoroughly rinsed with hot water and allowed to dry. However, the use of bleach
bottles for water storage is not recommended, because of the potential danger
of accidentally drinking bleach instead of water. If bleach bottles are used
for water storage, remove the bleach label and write “WATER” indelibly across
the bottle. Children may mistakenly associate the size and color of bleach
bottles with acceptable sources for drinking water and mistakenly drink bleach.
As such, bottles must be positively identified, and bleach must be kept out of
the reach of children.
If plastic containers are used, care should be taken to
assure that they are made of plastic approved for food contact by the Federal
Food and Drug Administration (FDA). Polyethylene plastic is approved for food
contact and is commonly used for containers of various sizes, including large
55 gallon drums. Certain types of plastic containers are not intended for food
contact (such as vinyl plastic waterbeds or trash containers) and may leach
undesirable chemicals into stored water. Leaching from approved plastics into
water is negligible.
Preparing Water for Storage
Stored water must be clean water. Use the best quality
available for water storage. Water must be from a system with a Division of
Drinking Water “Approved” rating. Water stored in thoroughly clean plastic or
glass containers can be chemically disinfected for long term treating each
gallon with 4 to 5 drops of liquid chlorine bleach (Clorox or Purex type
bleaches, containing 4% to 6% sodium hypochlorite). One teaspoon of bleach
disinfects 5 gallons of water. Allow 20 to 30 minutes before drinking. The
level of treatment will prevent growth of microorganisms during storage. Most
municipal water storages are already disinfected so no additional treatment is
necessary. Fill clean food grade container with tap water and screw on lids.
Storage Conditions
Store water containers away from cleaning supplies,
fertilizers and other products with strong odors. These odors could be absorbed
by the storage containers and transferred to the water.
Water stored in plastic containers should be filled to the
top so there is no air space and should be stored in a cool, dry location away
from petroleum and insecticide products, and away from strong odor food or
perfumed products.
Vapors from these substances could permeate the plastic and
affect the water. Thick walled polyethylene containers are significantly less
permeable to vapors than are thin walled containers.
Use of Stored Water
Store as much water as possible, more than the bare minimum
(especially in desert and hot climates). Be certain to label each container so
there will be no questions about its contents. Include the date and information
on the method of disinfection used.
- Water heaters.
- Soft water tanks.
- Melted ice cubes.
- Toilet tank (not bowl) provided no chemical sanitizers are used.
If a disaster catches you without a stored supply of clean
water, you can use the water in your house piping system, your hot water heater
and even ice cubes. Know the location of your house’s water shut off valve. In
a disaster in which your water company’s supply of water to your house has been
interrupted (e.g., broken water mains in the streets), shut off water supply
into your house to prevent backflow of contaminated water. To use the water in
your piping, let air into the plumbing by turning on the faucet in your house
at the highest level. A small amount of water will trickle out. Then, leaving
the highest faucet on, obtain water from the lowest faucet in the house.
To use water in your hot water heater, first turn off the
electricity or gas supply, and then close off the cold water supply line to the
water heater. Open the drain at the bottom of the tank and start the water
flowing by turning on a hot water faucet somewhere else in the house. Collect
the water containers and disinfect each gallon with 4 – 5 drops of liquid
bleach. Allow 20 to 30 minutes before drinking. (Note: If the water is cloudy
and/or from an unsafe origin, 16 drops of liquid chlorine bleach is
recommended.) You can use water in the tank of your toilet (not the bowl).
Disinfect as with water from the water heater.
Some water sources may have chemical contamination that makes
them unacceptable for drinking. For example, waterbed mattresses usually
contain organic chemicals in the wall plastic and biocidal chemicals in the
water to prevent algal, fungal and bacterial growth. These various chemicals
can make the water unsafe to drink. During an emergency such water may be used
for hand washing and laundering.
Emergency Outside Water Sources
- Rain water.
- Ponds and rivers.
- Untested wells and springs.
- Garden hose
Some emergencies may warrant obtaining water from sources
outside the home. The hazards of using water, including ice and snow, of
unknown quality needs to be carefully weighed against the obvious life
sustaining need for drinking water. Even crystal clear, mountain stream water
can be contaminated with disease causing parasites such as giardia.
Sterilization or disinfection can reduce the microbiological hazard of water of
unknown quality, but there is no safe method for reducing the chemical hazard
(e.g., toxic chemicals and radioactive materials) of water of unknown quality.
If water is cloudy, chemical disinfection must be supplemented by some kind of
filtration or heat sterilization (20 to 30 minutes of boiling) to assure
complete destruction of disease causing organisms. (Note: If water is cloudy
and/or from an unsafe origin, 16 drops of chlorine bleach is recommended.)
In addition to having a bad odor and taste, contaminated
water can contain microorganisms that cause diseases such as dysentery, typhoid
and hepatitis. You should disinfect all water of uncertain purity before using
it for drinking, food preparation or hygiene.
There are many ways to disinfect drinking water. None of the
listed methods are perfect. The methods described below will kill most
microbes, but they will remove very few chemical contaminants. Before water is
disinfected, let any suspended particles settle to the bottom of the container,
or strain the water through layers of paper towels, filters such as coffee,
clean cheese cloth, or clean cloth into a clean container.
Better clarification can be obtained by drawing cloudy water
through a “capillary siphon”.
A capillary siphon can be constructed by rolling a small,
clean, terry cloth towel into a long roll. Place one end of the roll into a
container of cloudy water. Drape the rest of the roll over the edge of the
container so that it hangs free from the container’s sidewall. Be sure the free
hanging (dry) end of the towel extends below the water level by several inches.
Place a clean container below the free hanging end. Soon water from the upper
container will wet the whole towel as the capillary action draws water through
the towel to the lower container. With cloudiness removed, chemical
disinfection can be more effective in destroying disease causing organisms.
Boiling
Boiling is the safest method of disinfecting water. It is preferred over any method of chemical disinfection because most disease causing microorganisms cannot survive the heat of the sterilizing boil. Water must be heated to boiling and held in a vigorous rolling boil for 5 minutes minimum (preferably 10 to 20 minutes). Let the water cool before drinking. Boiled water will taste better if you put oxygen back into it by pouring the water back and forth between two clean containers. This will also improve the taste of stored water.
Chemical disinfection of water is an acceptable alternative to heat sterilizing, but only if the water is clear. Disease causing organisms, such as viruses, can “hide” inside the microscopic dirt particles that cause cloudiness in water. They can thereby escape the action of the disinfecting chemical and remain capable of producing disease.
Chemical disinfection is less reliable than disinfection via
boiling because of several different factors. For example, the more organic
matter there is in the water, the more chemicals are required. The colder the
water is, the longer the “contact time” (the length of time between addition of
disinfecting chemicals to the water and use of the water) should be. Additional
factors affecting the success of disinfection includes the amount and type of
chemicals used, water pH (how acidic or basic the water is), and types of
disease causing organisms in the water.
Liquid Bleach
You can use household liquid bleach to kill microorganisms. Use only regular household liquid bleach that contains 5.25% sodium hypochlorite. Do not use scented bleaches, color safe bleaches or bleaches with added cleaners. Each gallon of water should be treated with 4 – 5 drops of liquid chlorine bleach or 16 drops of liquid chlorine bleach if the water is cloudy. This is just under ¼ of a teaspoon per gallon. One teaspoon of bleach disinfects 5 gallons of water. Treated water should be thoroughly mixed and allowed to stand for 30 minutes before using. A slight chlorine odor should be detectable in the water. If it is not, repeat the dosage and let it stand another 15 minutes before using. Treated water may have a slight chlorine taste, but this is additional evidence of safety.
Since liquid chlorine bleach loses strength over time, only
fresh bleach should be used for water disinfection. For bleach that is 1 to 2
years old, the dosage should be doubled. Bleach older than two years should not
be used unless absolutely necessary because of uncertainty as to how much the
active ingredients have deteriorated.
Iodine Tablets
Iodine tablets have the advantage of being more effective
against amoebic dysentery cysts and certain other intestinal parasite cysts
than chlorine-based disinfectants such as sodium hypochlorite or Halazone
tablets. Sporting good stores commonly carry iodine tables. Be certain iodine
tablets are fresh, since they lose effectiveness with age. Fresh tablets have a
gray color. They have a shelf life of approximately 3–5 years unopened. The
label should show an EPA registration number. Often iodine tablet containers
carry labels recommending restrictions on use by pregnant or lactating women.
Check the label before purchasing the tablets. Follow instructions on the
label, mixing thoroughly and allowing adequate “contact time”. The iodine
tablet should impart a light yellow to tan color to the water and a slight
odor.
Halazone Tablets
Halazone tablets (4 dichlorosulfamyl benzoic acid) for
emergency water disinfection are commonly carried by pharmacies and drug
stores. The label should show an EPA registration number. Be certain to note
the expiration date since the shelf life is only about 2 years. According to
the manufacturer: “It is important that the containers are tightly closed to
prevent the absorption of moisture from the air. If decomposition of the
tablets should occur, they take on a yellowish appearance, have a strong
objectionable odor, and of course, should not be used”.
Chemical disinfection, liquid bleach, iodine tablets, and
Halazone tablets will not remove cryptosporidium.
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