Colorado State University Extension
SafeFood Rapid Response Network


SAFEFOOD NEWS - Winter/Spring 1999 - Vol 3 / No. 2

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Water Storage

An unexpected blizzard, ice storm, tornado, or flood can create water supply and possibly water safety problems. In order to be prepared for such events, experts advise keeping at least a three-day supply of water on hand.

Amount of Water to Store

Whereas a quart of water or other fluid daily will sustain life (Department of Defense, Office of Civil Defense), it is generally recommended that a gallon of water per day per person be stored for food preparation and drinking purposes. This amount will provide added comfort and accommodate higher fluid needs at altitude or in warm climates. An additional 1/2 to 1 gallon per day is recommended for washing, tooth brushing, and dish washing.

Containers That Can be Used for Water Storage

Food-grade plastic or glass containers are suitable for storing water. One-, three- and five-gallon water containers can be purchased from most outdoor or hardware stores. Any plastic or glass container that previously held food or beverages also may be used. Examples include 2-liter soda bottles, and water, juice, punch or milk jugs.

Stainless steel can be used to store water; however, the water should not be treated with chlorine prior to storage as chlorine is corrosive to most metals.

Clean the used containers and lids with hot soapy water. Rinse with plain water and then sanitize the glass and plastic containers and lids by rinsing with a solution of 1 tablespoon chlorine bleach per gallon of water. Leave wet for two minutes, then rinse the containers again with clean plain water. Remember to remove the paper/plastic liners of lids prior to cleaning and to take extra care when cleaning hard-to-reach places like the handles of milk jugs.

To sanitize stainless steel containers, place in boiling water for 10 minutes. Never use containers that previously held chemicals!

Do I Need to Treat the Water?

Once you have properly cleaned your containers you can now fill them with potable or safe drinking water. All public water supplies are already treated and should be free of harmful bacteria. However, as an additional precaution, it is recommended that you add 5-7 drops (1/8 teaspoon) of chlorine bleach per gallon of water stored.

Where to Store Water

Clearly label all water containers "drinking water" with the current date. Store the water in a cool, dry place away from direct sunlight and heat sources. Do not store near gasoline, kerosene, pesticides or similar substances.

When potable water is stored properly, it should have an indefinite shelf life; however, it's a good idea to use and replace the stored water every 6 - 12 months.

If you have freezer space, storing some water in the freezer is a good idea. If you lose electricity, the frozen water will help keep foods in your freezer frozen until the power is restored. Make sure you leave 2 to 3 inches of head space in containers as water expands as it freezes.

Emergency Sources of Water

If you have not previously stored water and other sources of water are not available (commercial or other public sources) you can drain the water from your plumbing system. Unless you are advised that the public water supply has been contaminated and is not safe, water can be obtained by opening the drain valve at the bottom of the hot water heater. A typical water heater can hold 30-60 gallons of water. Discard the first few gallons if they contain rust or sediment. Make sure to let the water heater cool before draining to prevent a burn. The electricity or gas to the hot water heater will need to be turned off to prevent the heater from operating without water. Once water has been drained into containers, add 5-7 drops of chlorine bleach* per gallon water, stir or shake to mix and let set 30 minutes before using.

When and How to Treat Water for Storage

If an emergency occurs and you do not have water that you know is safe, it's possible to purify water for drinking. Start with the cleanest water you can find and treat with one of the following methods:

Boiling and chlorinating: Bring water to a rolling boil for 3-5 minutes at Colorado altitudes. It is safe to use the water once it has cooled. If you plan to store boiled water, let it cool to room temperature, then add 5 - 7 drops (or 1/8 teaspoon) of chlorine bleach* per gallon of water (1/2 teaspoon per 5 gallons), stir or shake to mix. Cap and store in cool, dry place.

Filtering and chlorinating: You can filter water if you have a commercial or backpack filter that filters to 1 micron. These are available in sporting good stores and are recommended for use when back-packing. They're not recommended to clean large volumes of water. Filtering will eliminate parasites such as giardia and cryptosporidium, but it may not eliminate all bacteria and viruses. Therefore, it's recommended that 5-7 drops (or 1/8 teaspoon) of chlorine bleach* be added per gallon of filtered water (1/2 teaspoon/5 gallons). Stir or shake to mix. Wait 30 minutes before using, or cap and store in cool, dry place.

*Use liquid household bleach that contains 5.25% hypochlorite. Do not use bleaches with fresheners or scents as they may not be safe to consume. The above treatment methods use a two-step approach so less bleach is needed, yet giardia and cryptosporidium are destroyed (via boiling) or eliminated (via filtering). Chlorine may not be effective against these parasites. Since adding too much chlorine to water can be harmful, it's important to be as accurate as possible when measuring.

Well Water

Contact your Public Health and Environment agency or local County Extension office for advice on testing, treatment, and storage of well water.

Updated Monday, August 29, 2011