Emergency Water Storage Calculator
Water gallons, jug count, and swap schedule for emergencies.
What it does
Clean water fails first in disasters: mains cut or contaminate while demand spikes. A counted stash sized to people and days turns panic buying into a marked shelf of sealed jugs.
The tool above takes people, days, and climate in gallons or liters. It returns the total, the jug count, and the rotation rule.
The default 4 people over 3 days needs 12 gal, or three 5 gal jugs. The metric mirror reads 45.4 L in three 20 L containers, swapped every 6 months.
Ready.gov fixes the federal numbers: a gallon per person per day for several days, 3/4 gallon of it drinking fluid, doubled in very hot weather, with home filled jugs replaced each 6 months. Red Cross kit lists echo the gallon a day baseline.
Storage discipline keeps the math honest. Commercial bottles stay sealed in cool dark places, home jugs get sanitized before filling, and suspicious water gets boiled a full minute or chlorinated before anyone drinks.
How to use
- Type the people covered.
- Type the days of autonomy.
- Pick normal or hot climate.
- Read total gallons or liters first.
- Read the jug count beside it.
- Mark the 6 month swap date.
Formula
- people
- People covered by the stash.
- days
- Days of autonomy, 1 to 30.
- climate
- Normal 1, hot weather 2.
Ready.gov sets one gallon per person per day for several days with about 3/4 gallon drinking fluid, doubled needs in very hot temperatures, and 6 month replacement for home filled containers. Red Cross kit guidance matches the gallon a day and multi day supply. Hot setting doubles per the federal heat note.
Worked example
Example: family of 4 for 3 days
Imperial defaults: 4 people, 3 days, normal climate.
- Household: 4 people over 3 days, normal weather.
- Need: 4 x 3 x 1 gal = 12 gal.
- Jugs: ceil(12 / 5) = 3 x 5 gal jugs.
- Drinking share: about 3/4 gal of the gallon per day.
- Rotation: swap stored water every 6 months.
- Tool shows 12 gal, 3 x 5 gal jugs, Swap stored water every 6 months.
Reference table
| Household | Need | Jugs |
|---|---|---|
| 4 people, 3 days | 12 gal | 3 x 5 gal |
| 2 people, 7 days hot | 28 gal | 6 x 5 gal |
| 2 people, 7 days | 53 L | 3 x 20 L |
| 1 person, 14 days | 14 gal | 3 x 5 gal |
Limits
- Drinking plus basic sanitation only.
- Kids, nursing, illness, and pets raise needs.
- Contamination events need treatment too.
- 30 day cap; longer needs resupply plans.
Common mistakes
- Storing a single case for a family.
- Forgetting the 6 month swap.
- Using milk jugs that sour and leak.
- Rationing without orders while dehydrating.
- Storing beside gasoline and cleaners.
Try it yourself
Quick checks. Answers sit tucked under each question.
2 people, 7 days, hot?
2 x 7 x 2 = 28 gal, six 5 gal jugs.
2 people, 7 days, metric?
2 x 7 x 1 = 14 gal = 53 L, three 20 L containers.
1 person, 14 days?
1 x 14 = 14 gal, three 5 gal jugs, swapped each 6 months.
Questions
How much water per person?
One gallon per person per day for drinking and sanitation, for several days. About 3/4 gallon of that is drinking fluid.
Hot climate adjustment?
Double it. Hot weather can double needs, and this tool applies x2 on the hot setting.
How do I store it?
Sealed commercial bottles in a cool dark place, or food grade containers you cleaned and sanitized. Replace home filled water every 6 months.
Sanitize containers how?
Sanitize with 1 tsp unscented bleach per quart of water before filling with chlorinated water.
Treat suspicious water how?
One full minute at a rolling boil, or 1/8 tsp bleach per gallon with a 30 minute stand and a slight chlorine smell.
Ration when short?
No. Drink your full need today and find more for tomorrow, unless authorities order rationing.