How much emergency water do I need?
The short version, a calculator for your own household, and what to do if the tap stops working.
Water calculator
Estimates only. "Children" are counted at a full gallon because they still need water for drinking, cooking, and washing. Pets are estimated at about one ounce per pound of body weight per day.
Why a gallon a day?
A gallon sounds like a lot to drink, and it is. The guideline covers roughly half a gallon for drinking and the rest for cooking, brushing teeth, and basic cleaning. It does not cover showers, laundry, or flushing toilets, so if you want those covered too, store more.
Who needs more than a gallon
- Hot weather. Heat can double what a person needs. If you live in the desert Southwest, or your plan includes a summer outage, use the "hot" box above.
- Nursing mothers, pregnant women, and anyone who is sick. Plan extra for each.
- Infants on formula. Powdered formula needs safe water to mix. Ready-to-feed formula avoids that problem entirely and is worth keeping a few days of.
- Pets. A common rule of thumb is about an ounce of water per pound of body weight each day. A 60-pound dog needs close to half a gallon.
Three days or two weeks?
Three days is the minimum, and it is the right size for a grab-and-go kit you might carry out the door. If you are staying home through a disaster, a water main break, or a long power outage, two weeks is the better target. Water is heavy (a little over 8 pounds a gallon), so most families keep the long-term supply at home and a smaller, portable supply in the car or by the door.
How to store it
Containers
- Store-bought bottled water is the easiest. Keep it sealed, and use or replace it by the date on the label.
- Food-grade water containers (5- to 7-gallon jugs, or 55-gallon barrels for larger households) work well. Look for containers sold specifically for drinking water.
- Avoid milk and juice jugs. They are hard to clean fully and the plastic breaks down over time.
- Never reuse containers that held chemicals, fuel, or anything non-food.
Where and how long
- Keep water somewhere cool and dark, away from direct sunlight and away from gas, pesticides, and other chemicals.
- Water you filled yourself should be replaced about every six months.
- Write the fill date on each container. If you can't remember when you filled it, it's time to refill it.
Water you may already have at home
If the tap stops working, your house is holding more water than you might think.
- A tank water heater holds 40 to 80 gallons. Turn off its power or gas first, let it cool, then drain from the valve at the bottom. Drain some sediment off before using it.
- Tankless (on-demand) water heaters have no reserve. If yours is tankless, don't count on it, and store more water instead.
- Your pipes. If authorities say the water supply may be contaminated, shut off the main valve to your house so dirty water can't come in. Then open the highest faucet, followed by the lowest, to collect what's left in the lines.
- Ice in the freezer is clean drinking water once it melts.
- Toilet tank water (the back tank, not the bowl) is fine for flushing and cleaning. Don't drink it, especially if you use tank cleaners.
How to make water safe to drink
Boiling (best)
Bring clear water to a rolling boil for one full minute, then let it cool. Above about 6,500 feet, boil for three minutes. If the water is cloudy, let it settle and pour it through a clean cloth or coffee filter first.
Bleach (if you can't boil)
Use plain, unscented household bleach. Check the label for the percentage of sodium hypochlorite, then add the amount below. Stir, and wait 30 minutes. The water should have a slight chlorine smell. If it doesn't, repeat the dose and wait another 15 minutes.
| Amount of water | 6% bleach | 8.25% bleach |
|---|---|---|
| 1 quart or liter | 2 drops | 2 drops |
| 1 gallon | 8 drops | 6 drops |
| 2 gallons | 16 drops (1/4 tsp) | 12 drops (1/8 tsp) |
Double the dose if the water is cloudy, colored, or very cold. Bleach loses strength over time, so use a bottle that's less than a year old. Never use scented, color-safe, or "splash-less" bleach.
Filters and tablets
Portable water filters and purification tablets are good backups, especially for a go-bag. Follow the instructions on the package, and know that many filters remove bacteria and parasites but not viruses or chemicals.
Know exactly how many days your water lasts
Days of Supply tracks the water you have stored alongside food, fuel, and supplies, and tells you how many days your household can actually last. It accounts for everyone in your home, including pets, and shows which resource will run out first.
See how many days your water lastsSources: Ready.gov, Water; U.S. EPA, Emergency Disinfection of Drinking Water; CDC, Water During Emergencies. This page is general guidance, not medical advice. Follow instructions from your local water utility and emergency officials during an event.