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Emergency Water Storage Calculator
Water is the most critical resource in an emergency. Without electricity, without municipal supplies or in the event of contamination, the capacity of a household to hold depends first on access to sufficient drinking water.
What is this calculator for?
- Estimate a reserve volume for the household, according to visible and adjustable assumptions.
- Adapt your reserve according to the number of people and the duration targeted.
- Help you build a progressive and realistic reserve, without excess or anxiety.
Open the water storage calculator to choose the people, duration, uses and stock already available.
Also plan the food and water needed for their preparation with the food reserve calculator. Food reserve calculator →
Using the water calculator
Open the water reserve calculator. It distinguishes consumption, food preparation and hygiene. Add separately the needs of your animals, not to mention twice the same reserve. Water reserve calculator →
How much water to expect per day?
For Quebec and Canada, the references below give a preparation mark of 4 liters per person per day in total :
- Consumption: 2 L per person per day.
- Food and hygiene: 2 L extra per person per day, to be divided according to usage.
- In the starting profile of the calculator, the distribution of these 2 L extra in 1 L for food and 1 L for hygiene is an adjustable choice of PrépaCivile, not an official prescription.
This is an emergency storage benchmark, not a medical prescription or a guarantee of coverage for all needs. Adapt volumes to heat, people, uses and local instructions.
An emergency reserve does not reproduce all the usual domestic uses. Define what will be essential and check the potability, containers and storage conditions: the calculator does not control them.
What is the target time for a water supply?
A frequent mistake is to want to plan everything at once. Preparedness is rather based on a progression in stages :
- 72 hours: a first preparation goal to consolidate.
- 7 to 14 days: optional scenarios to be assessed according to local risks and household means.
- 30 days: a larger storage scenario, to remember only if you can store, monitor and renew it properly.
Start small, consolidate that first tier, and then increase your capacity over time based on your space, budget, and environment (urban, home, rural).
The PrépaCivile method
The benchmarks proposed here are part of a responsible preparedness approach: reducing vulnerability without feeding fear or encouraging extreme behaviour.
- Organization: make an inventory of the water that is actually usable and the appropriate containers.
- Planning: distinguishing between uses, people and special needs.
- Transparency: Display the assumptions, units, and limits of the result.
To read next
- Water and food: predict food, its preparation and the rotation of reserves.
- Concrete application: check the containers and identify the remaining volume to be prepared.
- First step: establish a simple family plan and a 72-hour reserve adapted.
Sources and benchmarks
References for Quebec and Canada. Sources consulted on November 2, 2026.