Survival Water Calculator

About the Survival Water Calculator

Calculates how much emergency drinking and sanitation water to store for your household and the number of days you want to prepare for.

How to use

Enter the number of people and days, then click Calculate.

Worked example

4 people for 3 days → 12 gallons (about 45 litres) minimum.

How to use this calculator

1. Count everyone who depends on the water supply.
2. Choose how many days of emergency storage you want to cover.
3. Enter the water amount per person per day used by the calculator.
4. Multiply the three values to find the total gallons needed.

The formula explained

• \(\text{total gallons}\) = the total emergency water needed
• \(\text{people}\) = the number of people in the household
• \(\text{days}\) = the number of days you want to plan for
• \(\text{gallons per person per day}\) = the daily water amount assigned to each person

Step by step method

1. Start with the number of people in your household.
2. Multiply that by the number of days you want to prepare for.
3. Multiply the result by the gallons needed per person per day.
4. Use the final number to plan your emergency water storage.

Worked example

A family of 4 wants to prepare for 3 days of emergency water storage at 1 gallon per person per day.

1. Multiply the household size by the days: \(4 \times 3 = 12\).
2. Multiply by the daily water amount: \(12 \times 1 = 12\).

Tips and common mistakes

• Count every person who will rely on the supply, including children.
• Make sure the day count matches your preparedness goal.
• Use the same units throughout so the result stays accurate.
• If you are planning for extra safety, round up rather than down.

Frequently asked questions