Emergency Water Storage Calculator
Calculate how much emergency water to store for your household and pets using the standard one-gallon-per-person-per-day rule.
How it works
Gallons = (people × gallons/day + pets × 0.5) × days · 1 gallon ≈ 3.785 L
The standard emergency guidance is to store at least one gallon of water per person per day — roughly half for drinking and half for cooking and hygiene — with more in hot climates or for pregnant and sick people. Pets need water too, so an average dog or cat gets a modest daily allowance here. A three-day minimum covers short outages, but two weeks is the widely recommended target for households that can store it.
Worked example
A family of 4 preparing for 14 days at 1 gallon per person, plus one pet at half a gallon a day: (4 × 1 + 1 × 0.5) × 14 = 63 gallons, about 238 liters, or roughly 63 one-gallon jugs.
Sources: Ready.gov — Water
Frequently asked questions
How much water should I store per person?
The common standard is at least one gallon per person per day, covering drinking, cooking and basic hygiene. Store more in hot weather, at altitude, or for children, nursing mothers and anyone ill. A minimum of a three-day supply is advised, with two weeks preferred where storage allows.
How long does stored water last?
Commercially bottled, sealed water keeps for a long time — check the printed date and rotate it out periodically. Tap water stored in clean, food-grade containers should be replaced about every six months to stay fresh. Keep water in a cool, dark place away from chemicals and sunlight.
Does bottled or jugged water work better?
Both work. One-gallon jugs and 5-7 gallon containers store the most water per dollar and stack efficiently, while cases of small bottles are convenient to grab and ration. Many households keep a mix — bulk containers for the main supply and bottles for a grab-and-go kit.
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This calculator is for educational purposes. Double-check important results before acting on them.