Store at least 1 gallon of water per person per day for at least 3 days, and aim for a 2-week supply if you can, according to the CDC. Store-bought water in its original sealed bottles is the safest and simplest option. If you fill your own containers, use food-grade containers, sanitize them first, label them with the date, keep them somewhere cool and dark, and replace the water every 6 months.
That’s the short version. Below are the details from CDC, Ready.gov (FEMA’s preparedness site) and FEMA on how much to store, which containers to use, how to sanitize them, and how to make water safe if your supply runs out.
How much water to store
The baseline from both CDC and Ready.gov is 1 gallon per person per day, covering drinking and basic sanitation.
- Minimum: 3 days. For a family of four, that’s 12 gallons.
- Goal: 2 weeks. For a family of four, that’s 56 gallons.
Ready.gov notes that a normally active person needs about three-quarters of a gallon of fluids a day, including other drinks. The rest of the gallon covers cooking and hygiene.
Store more if your household includes:
- Children, nursing mothers or people who are sick (Ready.gov)
- Pregnant women (CDC)
- Pets (CDC)
- Anyone in a hot climate. Ready.gov says water needs can double in very hot temperatures.
- Medical needs that require extra water.
One more Ready.gov point that surprises people: don’t ration drinking water unless authorities tell you to. Drink what you need today and look for more tomorrow. Also skip caffeinated drinks and alcohol as a water substitute, since they dehydrate the body.
Option 1: Store-bought bottled water
The CDC calls unopened, commercially bottled water the safest and most reliable emergency water source. It’s sealed, it’s been processed, and it doesn’t need any prep.
- Keep it in its original sealed container.
- Store it in a cool, dark place.
- Check the expiration or “best by” date and rotate it into everyday use before then.
Bottled water is regulated by the FDA rather than EPA. For how the two compare day to day, see bottled water vs. tap water.
Option 2: Filling your own containers
Filling containers with tap water is cheaper and works well if you do it right.
Choose the right container
The CDC’s guidance:
- Best: food-grade water storage containers, sold at camping and surplus supply stores. If you’re unsure whether a container is food-grade, ask the manufacturer.
- If you can’t get food-grade containers, choose one that has a tight-closing lid, is unbreakable (not glass), and ideally has a narrow opening so you can pour without dipping in.
- Never reuse a container that held toxic chemicals, such as bleach or pesticides.
Clean and sanitize it first
CDC’s steps, in order:
- Wash the container with soap and rinse it completely.
- Mix a sanitizing solution of 1 teaspoon of unscented liquid household chlorine bleach in 1 quart (4 cups) of water. Use bleach that’s 5% to 9% sodium hypochlorite.
- Pour the solution in, cover the container tightly, and shake it so the solution touches every inside surface.
- Wait at least 30 seconds, then pour the solution out.
- Let the container air-dry.
- Fill it with clean water and close it tightly.
Label and store it
- Write “drinking water” and the date on each container.
- Store at 50°F to 70°F, out of direct sunlight.
- Keep it away from gasoline, pesticides and other chemicals.
- Replace the water every 6 months.
When you use stored water, CDC recommends pouring it or using a clean scoop each time. Don’t put your hands in the water or the container.
A simple rotation plan
Since home-filled water needs replacing every 6 months, tie it to dates you already remember. Many people use the clock changes for daylight saving time in spring and fall.
On rotation day:
- Use the old water for plants, cleaning or flushing toilets.
- Wash and sanitize the containers again.
- Refill, relabel with the new date, and put them back.
- Check the dates on any store-bought water and swap in fresh cases as needed.
The CDC’s 2025 hurricane preparedness guidance also suggests keeping a bottle of unscented bleach on hand for disinfecting water and cleaning. Because bleach loses strength over time, CDC suggests considering replacing that bottle each year.
Water you already have at home
If your stored supply runs low, the CDC lists several sources inside the home:
- Your water heater tank. Use the tank that supplies your faucets and showers. Never use water from radiators or boilers that are part of a home heating system.
- Melted ice cubes, as long as the water used to make them wasn’t contaminated.
- The toilet tank (not the bowl), only if the water is clear and hasn’t been treated with colored or chemical toilet cleaners.
- Liquid from canned fruits and vegetables.
Pool and spa water can be used for hygiene and cleaning, but not for drinking, according to CDC.
The CDC also notes that local officials may tell you to shut off your home’s main water valve to keep contaminated water out of your pipes. FEMA suggests moving clean ice into a cooler so you can keep the freezer closed.
These sources only help if your tap water was safe before the emergency. If there’s a drinking water advisory in effect, follow it. Our boil water advisory guide explains the different advisory types.
How to make water safe if you need to
If you have to use water you’re not sure about, CDC gives several methods. Boiling is the most reliable for germs.
Boiling
- Bring clear water to a rolling boil for 1 minute (3 minutes above 6,500 feet).
- Let it cool, then store it in clean, sanitized containers with tight covers.
- If the water is cloudy, filter it through a clean cloth, paper towel or coffee filter first, or let it settle and draw off the clear water.
Disinfecting with household bleach
Use unscented bleach that’s 5% to 9% sodium hypochlorite. CDC’s amounts:
| Amount of water | Bleach (5%–9%) |
|---|---|
| 1 quart or liter | 2 drops |
| 1 gallon | 8 drops (a little less than 1/8 teaspoon) |
| 5 gallons | 40 drops (1/2 teaspoon) |
- Double the amount if the water is cloudy, colored or very cold.
- Stir and wait at least 30 minutes before drinking.
Ready.gov adds that the water should have a slight bleach smell after treatment. If it doesn’t, repeat the dose and wait another 15 minutes. If it still doesn’t smell of chlorine, throw it out and find another source.
Avoid scented, color-safe or “added cleaner” bleaches. Check the label for the sodium hypochlorite percentage, since concentrations vary by brand.
Other methods
- Water treatment tablets: follow the label. CDC notes that iodine and chlorine tablets don’t kill Cryptosporidium, though chlorine dioxide does if used correctly. People who are pregnant or have thyroid problems should avoid iodine-treated water. See our guide to Cryptosporidium and Giardia for why that parasite matters.
- Most portable filters don’t remove viruses, so CDC recommends adding a chemical disinfectant after filtering.
What can’t be fixed
CDC is clear on this: water contaminated with fuel, toxic chemicals or radioactive material can’t be made safe by boiling or disinfecting. Use bottled water or another source, and contact your local health department.
Private well owners
A flood can contaminate a well even if your home stays dry. Plan to rely on stored water until the well has been disinfected and tested. Our well water testing guide covers what to test for after a flood.
Quick checklist
- [ ] 1 gallon per person per day, at least 3 days, ideally 2 weeks
- [ ] Extra for pets, pregnancy, illness, hot weather
- [ ] Store-bought water in sealed bottles, or food-grade containers you’ve sanitized
- [ ] Labeled “drinking water” with the date
- [ ] Stored at 50°F to 70°F, out of the sun, away from chemicals
- [ ] Home-filled water replaced every 6 months
- [ ] Unscented bleach on hand, replaced yearly
- [ ] Know where your main water shutoff valve is
To check your utility’s recent record before an emergency, search your water system.