Emergency water: 1 gallon per person, per day

Count people, then days

CDC says to store at least 1 gallon of water per person, per day, for at least 3 days, and to aim for a 2-week supply if possible. That gallon covers drinking, cooking, brushing teeth and washing up. The American Red Cross uses the same gallon and splits the time: a 3-day supply for evacuation and a 2-week supply for home. [S2] [S3] [S5]

A gallon is more than most people drink. Ready.gov says a normally active person needs about three quarters of a gallon of fluid a day, and the rest goes to sanitation. Needs go up with age, health and climate: children, nursing mothers and sick people may need more, and in very hot weather needs can double. CDC adds pregnant women, people who are sick and pets to the list of reasons to store more. [S2] [S3]

Store-bought water is the simplest

CDC calls unopened, commercially bottled water the safest and most reliable source in an emergency. Ready.gov says to keep it in its sealed original container in a cool, dark place. Check the expiration date on store-bought water and rotate it before then. [S2] [S3]

Where you keep it matters as much as how much. CDC says to store water at a cool 50 to 70°F, out of direct sunlight, and away from gasoline, pesticides and other toxic substances. A pantry shelf beats a sunny garage next to the lawn mower fuel. [S3]

Filling your own containers

If you bottle tap water yourself, CDC recommends FDA-approved food-grade water storage containers, which you can find at camping and surplus stores. If you can’t get one, pick a container with a tight-closing top, made of something durable and unbreakable (not glass), ideally with a narrow neck for pouring. Never reuse a container that held bleach, pesticides or another toxic chemical. [S3]

1. Wash. Clean the container with soap and rinse it with water. [S3]
2. Sanitize. Mix 1 teaspoon of unscented liquid household chlorine bleach (5 to 9% sodium hypochlorite) into 1 quart of water, pour it in, cap it and shake so it touches every inside surface. [S3]
3. Wait, then empty. Leave it at least 30 seconds, pour it out and let the container air-dry. [S3]
4. Fill and cap. Pour in clean water and close it with a tight lid. [S3]
5. Label it. Write “drinking water” and the date, and replace it every 6 months. Ready.gov gives the same 6-month rule for any water that wasn’t commercially bottled. [S2] [S3]

When you use it, CDC says to take water out with a clean scoop each time and keep your hands out of the water and the inside of the container. [S3]

When you’re living on it

Ready.gov’s advice is blunt: don’t ration drinking water unless authorities tell you to. Drink what you need today and try to find more for tomorrow, and cut how much your body needs by staying cool and less active. Drink water you know is safe first. Don’t swap water for carbonated or caffeinated drinks; Ready.gov notes that caffeine and alcohol dehydrate you. [S2]

Your house also holds some water you may not think of. EPA lists melted ice cubes and water drained from the hot water tank or pipes as other sources, but says to treat that water before you drink it. [S4]

If you have to treat water

Boiling and bleach kill most germs, but EPA notes that neither removes heavy metals, salts or most other chemicals. If water is cloudy, let it settle and filter it through a clean cloth, paper towel or coffee filter first. [S4]

• Boil. Bring it to a rolling boil for at least 1 minute, or 3 minutes above 5,000 feet. Let it cool, then store it in clean containers with covers. [S4]
• Or use bleach. Use regular, unscented chlorine bleach whose label says it is suitable for disinfection, fresh or stored at room temperature for less than a year. EPA’s dose is 8 drops of 6% bleach or 6 drops of 8.25% bleach per gallon, doubled if the water is cloudy, colored or very cold. [S4]
• Wait 30 minutes. The water should smell slightly of chlorine. If it doesn’t, repeat the dose and wait 15 more minutes. [S4]

The rest of the kit

Water is the first line of Ready.gov’s basic supply list. The rest fits in one or two easy-to-carry containers, like plastic bins or a duffel bag, with items sealed in airtight plastic bags. Since you don’t know where you’ll be when something happens, Ready.gov says to prepare supplies for home, work and cars. [S1]

Ready.gov also lists a fire extinguisher among the extras; our fire extinguisher guide explains the A-B-C label. For the backup battery, our power bank guide shows how to read its watt-hour rating. [S1]

Then keep it current. Ready.gov says to keep canned food cool and dry, keep boxed food in tightly closed plastic or metal containers, replace expired items and rethink the kit every year as your household changes. [S1]

Quick answers