Use one US gallon (about 3.8 litres) per person per day as a starting emergency-storage baseline. Plan for at least three days, then account for your household’s additional needs.
Set a starting target
The CDC recommends a three-day minimum and suggests two weeks if practical. Heat, illness, pregnancy and pets can require additional water. The calculator below estimates the people-only baseline; it does not calculate those extra needs.
Choose storage you can manage
Use commercially bottled water or suitable food-grade containers. Keep the reserve somewhere you can access, and include it in your household plan. Follow storage and replacement instructions from the manufacturer and local health authority.
Make the number useful
Count what is actually stored, not what you intend to buy. Write down the gap between your current supply and your target. Break that gap into manageable additions, and check that everyone knows where the reserve is kept.
Checklist
- Count household members.
- Choose a starting duration.
- Record stored water and the remaining gap.
Sources & further reading
Check these official sources for current advice and instructions relevant to your location.