How to Store Water Long Term

Co-authored by Mike Garcia

Last Updated: November 22, 2024 Approved

A natural disaster or other emergency could cut off water access for weeks. Storing your own supply addresses your most important need in this situation. Although water does not "go bad" in the same way that food does, it can breed harmful bacteria if you do not purify it or store it in safe conditions. The other risk is chemical contamination, either from certain types of plastic containers, or from chemical vapors that pass through the walls of the water containers.

Part 1

Part 1 of 2:

Preparing Sanitary Containers

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1
Decide how much water to store. The average person needs 1 gallon (4 liters) of water each day, half for drinking and half for food preparation and hygiene. Increase this number to 1.5 gallons (5.5 L) per person or more for children, nursing mothers, and sick people, and for anyone in a hot or high-altitude climate. Based on these numbers, try to store a 2 week supply for your household.^{[1]
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Research source} In case of an emergency evacuation, store a 3 day supply in easily transportable containers.^{[2]
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Trustworthy Source

Federal Emergency Management Agency
Federal agency responsible for coordinating responses to disasters and states of emergency

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- For example, 2 healthy adults and 1 child need (1 gallon or 3.8 liters / adult) x (2 adults) + (1.5 gal or 5.7 liters / child) x (1 child) = 3.5 gallons (13.25 liters) per day. A 2 week supply of water for this household is (3.5 gallons or 13.25 liters/ day) x (14 days) = 49 gallons (185.5 liters). A 3 day supply would be (3.5 gallons or 13.25 liters/day) x (3 days) = 10.5 gallons (40 liters).
2
Consider bottled water.^{[3]
X
Expert Source

Mike Garcia
Licensed Landscape Contractor

Expert Interview. 20 November 2020.} In areas that regulate bottled water, including the U.S. and E.U., sealed bottles of water are already sanitary and will stay good indefinitely. If you go this route, you do not need to worry about selecting appropriate containers or purifying the water.
- Check the label for certification by the IBWA (International Bottled Water Association), NSF (National Sanitation Foundation), or UL (Underwriters Laboratories). These demonstrate the product has met safety and quality standards.^{[4]
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  United States Environmental Protection Agency
  Independent U.S. government agency responsible for promoting safe environmental practices
  
  Go to source} This is more important in countries that do not regulate bottled water.
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3
Select food grade containers. Plastic food or beverage containers marked "HDPE" or with a #2 recycling symbol are excellent options.^{[5]
X
Research source} Plastics #4 (LDPE) and #5 (PP) are also safe, as is stainless steel. Never reuse a container that held anything besides food and drink, and only use brand-new empty containers if they are marked "food grade," "food safe," or with a knife and fork symbol.
- Milk and fruit juice leave residue that is difficult to remove and encourages bacterial growth. Do not reuse containers that held these drinks.^{[6]
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  Research source}
- Glass jars are a last resort, since they can easily break in a disaster.
- Traditional unglazed pottery jars can help keep water cool in warm climates. Use one with a narrow mouth, lid, and tap if possible to encourage sanitary handling.^{[7]
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  Research source}
Look for the resin identification code on plastic containers, which typically consists of a number printed next to the recycling symbol. Avoid containers marked “3” (for polyvinyl chloride, or PVC), “6” (for polystyrene, or PS), and “7” (for polycarbonate). These materials can be hazardous to your health.
5
Clean the containers thoroughly. Wash them with soap and hot water, then rinse. If a container previously held food or drink, disinfect it with one of the following methods:
- Fill with water and mix in 1 tsp (5 mL) liquid household bleach for every quart (approximately 1 liter) of water. Swish to touch all surfaces, then rinse well.^{[8]
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  Federal Emergency Management Agency
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  Go to source}
- For stainless steel or heat-safe glass, submerge in boiling water for 10 minutes, plus 1 minute for each 1,000 ft (300 m) of elevation above an altitude of 1,000 ft (300 m).^{[9]
  X
  Trustworthy Source
  
  National Center for Home Food Preservation
  Publicly-funded center dedicated to educating consumers about research-backed safety practices for preserving food
  
  Go to source} This is the best method for steel, since chlorine bleach can corrode the metal.^{[10]
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  Research source}
6
Disinfect water from unsafe sources. If your tap water is not safe to drink or if you get your water from a well, disinfect it right before storage. The best way to do this is to bring the water to a rolling boil for 1 minute, or 3 minutes at elevations above 5,000 ft (1,000 m).^{[11]
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United States Environmental Protection Agency
Independent U.S. government agency responsible for promoting safe environmental practices

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- If you cannot boil the water, or do not want to lose water by boiling it, bleach is the next best option:^{[12]
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  EDIS
  Electronic database of the University of Florida Institute of Food and Agricultural Sciences's peer-reviewed articles
  
  Go to source}
- Mix in ½ tsp (2.5 mL) of unscented, additive-free bleach for every 5 gallons (19 liters) of water. Double the amount of bleach if the water is cloudy or discolored.
- Let the water sit for half an hour.
- If you cannot smell a faint chlorine scent, repeat treatment and let sit another 15 minutes.
- In an emergency, you can also disinfect small amounts of water with water purification tablets. However, use these sparingly, as excessive use can impair thyroid function.^{[13]
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  PubMed Central
  Journal archive from the U.S. National Institutes of Health
  
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7
Filter out contaminants. Boiling or chlorine will kill microorganisms, but they will not remove lead or heavy metals. If your water is contaminated by runoff from farms, mines, or factories, pour it through an activated carbon filter and a reverse osmosis (RO) filter.^{[14]
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Electronic database of the University of Florida Institute of Food and Agricultural Sciences's peer-reviewed articles

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- You can make your own filter out of common materials. While not as effective as a commercial filter, it will remove sediment and some toxins.

Part 2

Part 2 of 2:

Storing the Water

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Take care not to touch the inside of the cap with your fingers, to avoid contamination.^{[15]
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Write "drinking water" on the side, along with the date you bottled it or purchased it.
3
Store in a cool, dark place. Light and heat can damage containers, especially plastic ones. Sunlight can also cause algae or mold to grow in clear containers, even sealed, store-bought bottles.^{[16]
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Research source}
- Do not store plastic containers near chemical products, especially gasoline, kerosene, and pesticides. Vapors can pass through some plastic containers and contaminate the water.^{[17]
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  Electronic database of the University of Florida Institute of Food and Agricultural Sciences's peer-reviewed articles
  
  Go to source}
- Store a 3 day supply in small containers near an exit, in case of an emergency evacuation.
4
Check on the supply every 6 months. If stored properly, unopened, store-bought bottled water should stay good indefinitely, even if the bottle has an expiration date.^{[18]
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Research source} If you bottled the water yourself, replace it every 6 months.^{[19]
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Trustworthy Source

Federal Emergency Management Agency
Federal agency responsible for coordinating responses to disasters and states of emergency

Go to source} Replace plastic containers when the plastic becomes cloudy, discolored, scratched, or scuffed.
- You can drink or use the old supply of water before replacing it.
5
Open 1 container at a time. If you need to use your emergency supply, store open water containers in a refrigerator or cold location. Use an open container within 3 to 5 days in the refrigerator, 1 to 2 days in a cold room, or a few hours in a warm room.^{[20]
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Research source} After that, purify the remaining water again by boiling it or adding chlorine.
- Drinking directly from the container or touching the rim with dirty hands increases the risk of contamination.

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Question

After you boil water, do you need to let it cool before filling up the container?

Anthony "TC" Williams
Experienced Landscaper
Anthony "TC" Williams is a Professional Landscaper in Idaho. He is the President and Founder of Aqua Conservation Landscape & Irrigation, an Idaho Registered Landscape Business Entity. With over 21 years of landscaping experience, TC has worked on projects such as the Idaho Botanical Garden in Boise, Idaho. He is a Idaho Registered Contractor and a previously Licensed Irrigator in the State of Texas.

Anthony "TC" Williams

Experienced Landscaper

Expert Answer

Yes. This is especially important if you are pouring it into a plastic or soft sided container.

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Question

How much bleach should I use for a 50 gallon (190 liter) drum?

Anthony "TC" Williams
Experienced Landscaper
Anthony "TC" Williams is a Professional Landscaper in Idaho. He is the President and Founder of Aqua Conservation Landscape & Irrigation, an Idaho Registered Landscape Business Entity. With over 21 years of landscaping experience, TC has worked on projects such as the Idaho Botanical Garden in Boise, Idaho. He is a Idaho Registered Contractor and a previously Licensed Irrigator in the State of Texas.

Anthony "TC" Williams

Experienced Landscaper

Expert Answer

For storage, add 1/2 teaspoon (2.5 ml) of unscented household bleach to 5 gallons (19 liters) of water. A 50 gallon (190 liter) container would require 5 teaspoons (25 ml). Double the amount of teaspoons or milliliters if water is cloudy.

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Do you fill the containers to the top or leave some space in them?

Community Answer

Fill it up to the top. The less air inside the bottle the better.

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Tips

Bottled water is not necessarily higher quality than tap water — and in some cases, it is tap water.^{[21]
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Go to source} The advantage for storage is the commercially sealed bottle.

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For emergencies, keep a portable water filter, like a Lifestraw, on hand. These can be used to filter bacteria out of water without the use of heat.^{[22]
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Mike Garcia
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Expert Interview. 20 November 2020.}

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Consider freezing some of your water so you have a short-term way to store perishables if the power goes out. Freeze water in plastic containers with a couple inches (a few centimeters) of head space, as the expanding ice can break glass or overfilled containers.^{[23]
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Warnings

If you notice a leak or hole in the containers after having stored the water, do not drink from the container.

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Do not use scented or color-safe bleach to purify water, or bleach with added cleaners, or bleach with a greater than 6.0% concentration. Bleach gradually becomes less effective if the bottle has been opened, so use a new container for best results.^{[24]
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Iodine tablets and other non-chlorine water treatments are not recommended, since they kill fewer microorganisms than chlorine.^{[25]
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