Water Storage Calculator
Enter your household and how many days you want to cover. We use the standard of 1 gallon per adult per day (and 0.75 for children) to estimate the gallons — and 55-gallon barrels — you need to store.
You should store about
— gallons
How long will your water last?
Already have water put away? Enter the gallons you have on hand and your household to see how many days, weeks, and months it covers, using 1 gallon per adult per day (0.75 for children).
Your supply lasts about
— days
How the calculation works
The accepted emergency minimum is one gallon of water per adult, per day — roughly half for drinking and half for cooking and hygiene. We estimate children at 0.75 gallons. Multiply by your number of days, then divide by 55 to see how many standard food-grade barrels that takes.
Tip: hot climates, pets, and medical needs increase usage — round up. A common target is two months per adult (about 60 gallons each). Empty and refill stored water every six months to keep it fresh.