Emergency Water Calculator

The WHO recommends at least 4 litres of water per person per day in emergency situations. This calculator helps you estimate your required supply.

EmergencyKitLab Canada Team Actualitzat: juliol del 2026
Basat en: Public Safety Canada WHO Canadian Red Cross Health Canada

Calculate your water reserve

Your calculation results

Total supply needed

27

litres

Per person/day

4.5

litres

Climate factor

x1.5

multiplier

Backup purification

In addition to your stored supply, always keep an emergency purification system ready: water purification tablets (1 tablet per liter) or a portable filter like the LifeStraw. This lets you use rainwater or water from uncertain sources if your supply runs out.

How to store emergency water properly

Water is the most critical resource in any emergency. A person can survive weeks without food but only days without water. Here are the basic recommendations from the WHO and Public Safety Canada:

Recommended amounts

  • Adults: at least 2 litres per person per day (drinking + basic hygiene)
  • Children: at least 0.75 litres per day (lower body weight but faster dehydration)
  • Hot climate: needs increase by up to 50% in summer, especially during heat waves
  • Pets: add 0.25–0.5 litres per animal per day

Storage tips

  • Use food-grade water containers in 5 or 7 litre sizes: easy to handle and stackable
  • Store in a cool, dark place away from chemicals
  • Rotate tap-filled containers every 6 months
  • Sealed commercial bottled water keeps 1–2 years with no issues
  • Label each container with the fill date

Alternative sources in an emergency

If your supply runs out, you can use rainwater, water from your hot water heater, or cisterns. Always treat water from uncontrolled sources with purification tablets, portable filters, or by boiling for at least 1 minute (3 minutes above 6,500 feet).

Need a more complete plan?

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