Emergency Water Storage Calculator

Number of People in Household

Emergency Duration (Days)

Minimum Water Rate (Gallons per Person per Day)

Minimum Required Storage

Total Water Storage Needed US Gallons

This estimate provides the minimum required water (1 gallon/person/day) for drinking and basic sanitation. Consider increasing the reserve for cooking or medical needs.

Why Water Storage is Essential

Most people underestimate how quickly water needs add up. According to the U.S. Federal Emergency Management Agency (FEMA), you should store at least one gallon of water per person per day.

That minimum covers:

Drinking water
Basic hygiene (hand washing, brushing teeth, limited cleaning)
Minimal sanitation

But in reality, you may need more if you consider:

Cooking needs
Medical care
Hot climates (where you’ll drink more)
Infants, elderly, or pets

This is why having a calculator that accounts for your family size and duration makes planning much easier.

How the Emergency Water Storage Calculator Works

The calculator takes three simple inputs:

Number of people in your household
Emergency duration in days
Water rate per person per day (default: 1 gallon)

Formula in Plain English:

Total Water Storage (gallons) = People × Days × Gallons per Person per Day

It then shows the minimum gallons of water your family should store.

Example Calculation

Let’s say you have:

4 people in your household
You want to be prepared for 3 days
You use the default rate of 1 gallon per person per day

Step 1: 4 × 3 × 1 = 12 gallons

You’ll need at least 12 gallons of water stored.

But if you want a buffer (for cooking, pets, or comfort), you may decide to store 15–20 gallons instead.

Benefits of Using the Calculator

Accuracy → No guesswork, just clear numbers
Peace of mind → Know your family is covered for emergencies
Customizable → Adjust for longer durations or higher water needs
Practical for preppers and households alike

Instead of just storing a random number of bottles, you’ll have a data-backed plan for how much water is really needed.

Tips for Safe Emergency Water Storage

Use food-grade containers – Never store water in containers that held chemicals.
Rotate storage every 6–12 months – Even sealed water can degrade over time.
Keep containers in a cool, dark place – Avoid direct sunlight and heat.
Disinfect if necessary – Add unscented household bleach (⅛ teaspoon per gallon) if using non-bottled water.
Don’t forget pets – Plan extra storage for animals in your household.