The baseline is simple: store at least one gallon of water per person per day. Plan for a minimum of three days if you may need to evacuate, and aim for a two-week supply to shelter at home. For a family of four, two weeks works out to about 56 gallons. Below we show where that number comes from, when you need more, and how to store water so it stays safe.
One gallon per person per day is the widely used planning figure, split roughly in half between drinking and basic cooking and hygiene. That is a baseline, not a maximum. You need more in hot weather, at high altitude, during heavy physical activity, and for anyone who is pregnant, nursing, or sick. Do not forget pets: as a rough guide, plan for about an ounce of water per pound of body weight per day for dogs and cats, and check with your vet for specifics.
Match the supply to the scenario. For a grab-and-go bag meant for evacuation, three days per person is the common minimum because you are mobile and weight matters. For sheltering in place at home, where the real risk is a longer disruption, two weeks is a far more reassuring target and is increasingly the recommended home standard. If you have the space, more is better, because water is heavy to move once an emergency starts.
Here is the whole calculation: people, times one gallon, times days, plus extra for pets and heat, equals gallons to store. A worked example for a family of four storing two weeks: 4 people times 1 gallon times 14 days is 56 gallons, before adding anything for pets or a hot climate. If that sounds like a lot, remember it is the supply you are least able to improvise once the tap stops.
| Who or what | Daily planning amount | Notes |
|---|---|---|
| Each person | 1 gallon | Half drinking, half cooking and hygiene |
| Hot climate or activity | Add to the per-person figure | Heat and exertion raise needs sharply |
| Pregnant or ill | More than baseline | Plan generously for these |
| Dogs and cats | About 1 oz per lb of body weight | Confirm with your vet |
Choose based on your space and how mobile you need to be. Commercially bottled water is simple and dated. Food-grade containers and stackable water bricks suit closets and shelves. A sealed 55-gallon drum stores a lot in a small footprint for a stay-at-home supply but is not portable. A bathtub bladder lets you capture many gallons fast when an emergency is forecast. Whatever you use, it must be food-grade and clean, never a container that held chemicals.
Sealed commercial bottled water keeps until its printed date. Tap water you bottle yourself stays good for roughly six to twelve months in clean food-grade containers, after which you should empty and refill. The enemies of stored water are heat, light, and nearby chemicals, so keep it cool, dark, and separate from fuel, cleaners, and pesticides. Label every container with the date you filled it so rotation is easy.
Store at least one gallon per person per day, with roughly half for drinking and half for cooking and hygiene. Many emergency agencies suggest a three-day supply at a minimum for evacuation and a two-week supply for sheltering at home.
Using one gallon per person per day, a family of four needs about 56 gallons for 14 days. Add more for pets, hot climates, pregnancy, or anyone who is ill, since those raise daily needs.
Commercially bottled water keeps until its printed date if sealed and stored cool and dark. Tap water you bottle yourself in clean food-grade containers should be replaced about every six to twelve months. Keep all stored water away from heat, light, and chemicals.
Municipal tap water is already treated, so clean food-grade containers and good storage are usually enough. If you are unsure of the source or the containers, you can treat water before storage following EPA guidance, which we cover in our purification guide.
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