Pat Kendall and Melissa Bardsley, Colorado State University Extension food science and human nutrition specialists and Glenn Bodner, Colorado Department of Health and Environment, Division of Water Quality and Control, drinking water engineer
An unexpected blizzard, ice storm, tornado or flood can create water supply and safety problems. 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, according to the Department of Defense and the Office of Civil Defense, it is recommended that a gallon of water per day per person be stored for food preparation and drinking. A gallon provides added comfort and accommodates increased fluid needs at higher altitudes or warm climates. An additional one-half to 1 gallon per day is recommended for bathing and hygiene, and to wash dishes.
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
glass container that previously held food or beverages such as 2-liter soda bottles or water, juice, punch or milk jugs, also may be used. Stainless steel can be used to store water which has not been or will not be treated with chlorine; chlorine is corrosive to most metals.
Clean used containers and lids with hot soapy water. Once the containers have been thoroughly cleaned, rinse them with water and sanitize the containers and lids by rinsing them with a solution of 1 tablespoon chlorine bleach per gallon of water. Leave the containers wet for two minutes, then rinse them again with water. Remember to remove the paper or plastic lid liners before washing the lids. It is very difficult to effectively remove all residue from many containers, so carefully clean hard-to-reach places like the handles of milk jugs. To sanitize stainless steel containers, place the container in boiling water for 10 minutes. Never use containers that previously held chemicals.
Do I Need to Treat Water?
Once you properly clean containers, 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, about 1/8 teaspoon, of chlorine bleach per gallon of water stored. This precaution protects you against any lingering organisms in storage containers that may have been inadvertently missed during the cleaning process.
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 it near gasoline, kerosene, pesticides or similar substances.
When potable water is properly stored, it should have an indefinite shelf life; however, it’s a good idea to use and replace the stored water every 6 – 12 months. Rotating water this way provides you with an opportunity to experiment and check the amount of stored water against what you require. It also serves as an additional precaution against bacteria or viruses growing in containers which may not have been thoroughly or properly cleaned and sanitized.
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 space in containers because water expands as it freezes.
Emergency Sources of Water
In an emergency, if you have not previously stored water and commercial or public sources of water are not available, drain water from your plumbing system. Unless you are advised that the public water supply has been contaminated and is not safe, open the drain valve at the bottom of the water heater and salvage the water stored in the heater. A typical water heater holds 30-60 gallons of water. Discard the first few gallons if they contain rust or sediment. Let the water heater cool before draining it from the heater so it does not scald you. Turn off the electricity or gas to the water heater to prevent the heater from operating without water. Once water has been drained into clean, sanitized containers, add 5-7 drops of chlorine bleach* per gallon of water, and stir or shake the solution to mix it. Let it set 30 minutes before use.
When and How to Treat Water for Storage
In an emergency, if 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: Water can be purified by boiling. Boiling times may vary from state to state, depending on altitude. In Colorado, the water is safe to use once after it has been boiled for three to five minutes and has cooled. If you plan to store boiled water, pour it into clean, sanitized containers and 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 the solution to mix it. Cap the containers and store them in a 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 goods stores and are recommended for use when back-packing. They are not recommended to clean large volumes of water. Filtering eliminates parasites such as giardia and cryptosporidium, but it may not eliminate all bacteria and viruses. Therefore, it’s recommended that 5-7 drops (1/8 teaspoon) of chlorine bleach* be added per gallon of filtered water (1/2 teaspoon for 5 gallons). Stir or shake the solution to mix it. Wait 30 minutes before using the water, or cap the containers and store them in a cool, dry place.
*Use liquid household bleach that contains 5.25 percent 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 through boiling or eliminated by 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.
Contact your Public Health and Environment agency or local Colorado State University Extension office for advice on testing, treatment, and storage of well water.
- Storing and Treating Emergency Home Water Supplies, University of Idaho Extension, 1993.
- Water Storage, Utah State Extension, 1999.
- Safe Drinking Water in an Emergency, Larimer (CO) County Department of Health and Environment, 1999.