How much water do you need per person for 72 hours?
Plan for at least 4 liters (about 1 US gallon) of water per person per day — 2–3 liters for drinking and the rest for cooking and basic hygiene. For 72 hours that is 12 liters (about 3 gallons) per person, so a family of four needs about 48 liters (12–13 gallons).
Water for 72 hours by household size
| People | Per day | 72 hours | In 1.5 L bottles |
|---|---|---|---|
| 1 | 4 L (1 gal) | 12 L (3 gal) | 8 bottles |
| 2 | 8 L (2 gal) | 24 L (6 gal) | 16 bottles |
| 3 | 12 L (3 gal) | 36 L (9.5 gal) | 24 bottles |
| 4 | 16 L (4 gal) | 48 L (12.5 gal) | 32 bottles |
Add more in hot weather, for physical work, for pregnant or breastfeeding women and for people who are ill. Count pets separately: a medium-sized dog needs about 1 liter a day.
Where the 4 liters go
- 2–3 liters for drinking (an average adult, more in heat).
- About 1 liter for preparing food — rice, pasta and beans need water.
- The rest for washing hands and brushing teeth.
Toilet flushing is not included: keep a bucket of non-drinking water (from the bathtub, for example) for that.
How to store it
- Sealed store-bought bottles are the simplest option — check the date and rotate them.
- Refill your own containers only if they are food-grade and clean (PET bottles from water or soda; never milk jugs or containers that held chemicals).
- Keep water dark, cool and off the floor, and label home-filled containers with the date.
Start with 3 days, then build up
The EU, FEMA and the Red Cross recommend that every household can cope on its own for at least 72 hours. Once you have 3 days, extend to 2 weeks: about 56 liters (15 gallons) per person.
Water
Storing, filtering and disinfecting water when the power and the tap are both gone
Worksheets (appendices)
- The Water Is Off — What First?
- Personal Water Plan
- Labels for Water Containers
- Water Supply Log
- Equipment by Priority
- Local Information Card
- Worked Example — Apartment and House
Sources: CDC — Creating and Storing an Emergency Water Supply; FEMA / Ready.gov — Water; EU Preparedness Union Strategy (2025). Sources are listed on the last page of every guide.
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