Water — Track 1: Store
One gallon per person per day is the CDC floor — not the target. Here is how to calculate what your household actually needs, adjusted for climate, pets, and medical requirements.
The baseline
The CDC and Ready.gov both state the same starting point: one gallon of water per person per day.[1] Half of that is for drinking. The other half covers minimal hygiene — hands, face, basic sanitation.
That number is useful because it is simple and easy to act on. It is not a comfortable daily water budget. Under ordinary household conditions — cooking, washing dishes, brushing teeth — most adults use two to three times that amount without thinking about it. The CDC figure is the floor for a survival scenario, not the target for a prepared household.
A more honest planning number is 1.5 gallons per person per day for a household with running water that suddenly loses it, or 2 gallons per person per day if you want to maintain reasonably normal hygiene through a 72-hour or two-week disruption.
The calculator below works with all three numbers. Use whichever matches your situation. The page you're reading covers the math; once you have a number, Emergency Water Storage covers how to store it.
Daily water by use
The 1 gal/person/day rule is the minimum for survival under emergency conditions. It assumes no water for laundry, no flushing toilets, and very limited hygiene. Plan for more if you can.
Adjustments
Several factors can significantly increase daily water needs. Check each one against your situation before setting your storage target.
Physical exertion in heat can increase fluid needs to two to four times the baseline.[2] If your disruption scenario involves outdoor work, loss of air conditioning, or summer temperatures above 90°F, add at least 50% to your daily per-person figure.
Add: 0.5–1 gal / person / day
Formula-fed infants require safe water for formula preparation — typically 32 oz (0.25 gal) per day for newborns, increasing with age. Children have lower absolute needs but higher needs per pound of body weight. If bottles or formula are in use, plan extra for mixing, sterilizing, and cleanup.
Add: 0.25–0.5 gal / infant / day
Kidney disease, diabetes, certain medications, and high-sodium diets all increase daily fluid requirements. Pregnant women need approximately 10 cups of total fluids per day; breastfeeding mothers need about 13 cups.[3] Consult your care team for a specific number if this applies.
Add: 0.25–1 gal / person / day
Dogs need roughly 1 oz of water per pound of body weight per day — a 40-lb dog needs about 40 oz, just over 0.3 gallons. Cats need about 4 oz per day. These are minimums for sedentary conditions; active or working animals need more. Do not omit pets from your calculation.
Freeze-dried and dehydrated foods require water to rehydrate — often 1.5 to 2 cups per serving. Dry beans, rice, and grains also require cooking water. If your food storage plan relies heavily on these foods, your water requirement increases substantially. See Water for Food Storage for the full calculation.
Add: 0.25–0.5 gal / person / day
Anyone doing sustained outdoor labor during a disruption — clearing debris, hauling water, generator maintenance, garden work — will need significantly more than the baseline. At moderate exertion, an adult loses 0.5 to 1 liter per hour through sweat. Plan for your scenario, not for sitting on the couch.
Add: 0.5–1 gal / laboring adult / day
Storage calculator
Enter your household composition and target storage window. The calculator applies the CDC baseline with adjustments for your specific situation.
Household members
Your situation
Daily total
—
gallons / day
Total to store
—
gallons
Weight (approx.)
—
lbs
How to store it
—
7-gal Aqua-Tainers
—
3.5-gal WaterBricks
—
55-gal drums
Container counts are rounded up to the nearest whole unit. Actual storage may vary based on what you have on hand. Container comparison guide
Quick reference
At 1.5 gallons per person per day — the realistic planning figure — including no pets, no climate adjustment, and no medical additions.
| Household | Daily | 72 hours | 7 days | 14 days | 30 days |
|---|---|---|---|---|---|
| 1 person | 1.5 gal | 4.5 gal | 10.5 gal | 21 gal | 45 gal |
| 2 people | 3 gal | 9 gal | 21 gal | 42 gal | 90 gal |
| Family of 3 | 4.5 gal | 13.5 gal | 31.5 gal | 63 gal | 135 gal |
| Family of 4 | 6 gal | 18 gal | 42 gal | 84 gal | 180 gal |
| Family of 5 | 7.5 gal | 22.5 gal | 52.5 gal | 105 gal | 225 gal |
| 6+ people | 9+ gal | 27+ gal | 63+ gal | 126+ gal | 270+ gal |
At CDC minimum (1 gal/person/day), halve these figures. At comfortable use (2 gal/person/day), multiply by 1.33.
What to do next
The three pages that turn your calculation into a working water supply.
Step 2
Container types, placement, filling and rotation schedules. The guide to building the physical storage once you know your target.
Read guide
Equipment
Every container type from 7-gallon jugs to 55-gallon drums — specs, costs, and which one fits your space.
Compare containers
Small spaces
How to store a meaningful water supply in a small apartment without giving up living space — practical options for renters.
Read guide
Part of the Water Preparedness section
Back to Water Preparedness