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Preparedness & Self-Reliance Tool

Water Storage Calculator

Enter container size and count to see your total water reserve in gallons, litres, weight, and person-days of supply.

Also handy: Emergency Water Needs Calculator, Fuel Storage Calculator

Calculate water storage capacity

Enter your container size and how many containers you have. This calculator estimates total stored water in gallons and litres.

Container inventory

Enter the amount one container can hold.
Enter how many containers you plan to store.
Live results update as you type
Estimated Result

50 gallons

Based on 10 containers holding 5 gallons each.

10 Containers
50 Total gallons
189 Total litres

Your storage, visualized

417 lb Total weight
50 days 1-person supply (1 gal/day)

How to use this calculator

Enter the size of one water container, choose the size unit, and enter how many containers you have. The calculator estimates the total amount of stored water in gallons and litres.

Tips for success

  • Label and rotate stored water regularly. Fill date labels and a 6–12 month rotation schedule prevent stale water from being overlooked.
  • Use food-safe containers for drinking water. Look for HDPE (#2 plastic) containers designed for water storage. Never repurpose milk jugs or soda bottles for long-term storage.
  • Store in a cool, dark place. Sunlight and heat accelerate algae growth and plastic off-gassing. A cool basement or closet is ideal.
  • Small containers are portable; barrels are efficient. 5-gallon jugs are the most practical for moving water in an emergency. 55-gallon barrels hold more but require a hand pump.
  • Plan for more in hot weather or longer outages. FEMA's 1 gallon/person/day minimum assumes mild conditions. Double it for summer heat or strenuous work.
Stored water has no fixed expiration, but quality depends on container, fill method, and storage conditions. Commercially bottled water is typically labeled for 1–2 years; home-filled food-grade containers are best rotated every 6–12 months. Watch for cloudiness, off-taste, or odor, those are signs to replace rather than rely on. For long-term storage, keep containers off concrete, out of direct sunlight, and away from gasoline or solvent fumes that can permeate plastic.

Common mistakes

  • Mixing litres and gallons. Double-check the unit toggle if switching between container types.
  • Counting unfilled containers. Only count containers that are actually filled and sealed.
  • Assuming containers are completely full. Containers should be filled with a small air gap to allow for temperature expansion.
  • Forgetting hygiene and cooking water. FEMA's 1 gallon minimum is drinking water only. Budget an extra gallon per person per day for sanitation.
  • Ignoring rotation schedules. Old stored water won't always smell or look bad, but it can harbor bacteria if improperly stored.

FAQ

Can I use litres instead of gallons?

Yes. This calculator supports both litres and US gallons for container size.

Does this tell me how long my water will last?

No. This tool estimates storage capacity only. Use it alongside an emergency water needs calculator to estimate duration.

Can I use this for barrels?

Yes. It works for small jugs, drums, barrels, and most other water containers.

How many litres are in one US gallon?

One US gallon is about 3.785 litres.