Foto: Michael Burrows / PexelsWater Storage Calculator: How Many Liters Does Your Household Need for 14 Days?
Calculate exactly how much water your household needs for a 14-day emergency. Includes calculator method, container recommendations, and storage guide for families.
The Water Calculator Formula
Use this simple formula to determine your household's water storage target:
Total liters = (Number of adults × 5L) + (Number of children × 3L) + (Pets: dog × 1L, cat × 0.3L) × Number of days
Quick Reference Table
| Household | 3 Days | 7 Days | 14 Days |
|---|---|---|---|
| 1 adult | 15 L | 35 L | 70 L |
| 2 adults | 30 L | 70 L | 140 L |
| 2 adults + 1 child | 39 L | 91 L | 182 L |
| 2 adults + 2 children | 48 L | 112 L | 224 L |
| 4 adults | 60 L | 140 L | 280 L |
| Family of 4 + 1 dog | 67 L | 154 L | 308 L |
Why 5 Liters Per Adult Per Day?
Many sources cite 2 liters (drinking only) or FEMA's 1 gallon (3.8 liters) as the minimum. Five liters per person per day is the practical recommendation for a realistic quality of life:
- Drinking: 2.5–3 L (including water used in tea, coffee, cooking)
- Basic cooking: 0.5–1 L (pasta water, soups, cleaning cutting boards)
- Face/hands/dental hygiene: 0.5 L
- Buffer: 0.5 L (illness, extra physical activity, spillage)
In hot weather or with physical exertion, drinking needs rise to 3–4 L/day. The 5 L/day figure accounts for this without creating excessive waste.
Container Requirements
Calculating Containers Needed
Divide your total liter requirement by your container size:
| Total Liters Needed | 5L Bottles | 10L Containers | 20L Jerrycans | 55-gallon Barrel (208L) |
|---|---|---|---|---|
| 70 L (1 adult/14d) | 14 | 7 | 4 | — (overkill) |
| 140 L (2 adults/14d) | 28 | 14 | 7 | 1 (with 68L left) |
| 224 L (family 4/14d) | 45 | 22 | 11-12 | 1 (with 16L extra) |
Recommendation for most households: 20-liter HDPE jerrycans strike the best balance between manageable weight (20 kg when full), storage efficiency, and cost (€5–10 per container).
The Storage Space You'll Need
Before purchasing containers, assess your storage space:
20-Liter Jerrycan Dimensions (Typical)
- Height: approximately 45 cm
- Width: approximately 27 cm
- Depth: approximately 18 cm
Space Estimates
| Household (14-day supply) | Jerrycans | Approximate Floor Space |
|---|---|---|
| 2 adults | 7 | ~0.3 m² (3 rows of 2–3) |
| Family of 4 | 11–12 | ~0.5 m² |
| Extended family (6) | 17–18 | ~0.75 m² |
A standard storage shelf in a basement or pantry can hold a 2-adult supply in a single stack. This is not a large footprint.
Beyond 14 Days: Extended Storage Options
For households with space and resources, extending to 30 or even 90 days provides exceptional resilience against prolonged events.
30-Day Supply
| Household | Total Liters | 20L Containers | Approximate Cost |
|---|---|---|---|
| 2 adults | 300 L | 15 | €75–150 |
| Family of 4 | 480 L | 24 | €120–240 |
55-Gallon Barrels for Larger Households
At 208 liters per barrel, two barrels provide a 2-adult 14-week supply. This becomes cost-effective at scale:
- Barrel cost: €80–120
- Barrel pump: €20–30
- Much lower per-liter cost than individual jerrycans
Requirement: a pump or siphon for access. Location must be chosen before filling — a full 55-gallon barrel weighs over 200 kg and cannot be moved.
Special Considerations
Infants
Infant formula preparation requires clean water. For bottle-fed infants, add 1–2 additional liters per day to your calculation. Breastfed infants require no additional water allocation but the nursing mother needs 0.5–1 L additional per day.
People with Medical Conditions
High-salt diets (heart failure medication, certain kidney conditions) require higher water intake. Diabetes, particularly in hot conditions, increases hydration needs. Consult your doctor about appropriate targets.
Summer vs. Winter
Winter requires less drinking water (lower sweat rate) but more for hygiene (hands, face) as people spend more time indoors. Summer requires more drinking water but cold washing becomes less critical for comfort.
A 5 L/day target accommodates both seasons without adjustment.
How to Build Your Supply in Stages
Stage 1: Emergency Minimum (This Week)
- 2 × 20L jerrycans per adult = 3-day minimum supply per person
- Cost per person: ~€10 for containers
Stage 2: Standard Supply (This Month)
- Fill to 14-day supply target
- Test your storage location conditions
Stage 3: Extended Supply (This Quarter)
- Extend to 30 days if space permits
- Add filtration equipment for backup sourcing
Maintenance Cost After Initial Setup
Once your supply is established:
- Every 6 months: rotate water (use, refill, relabel)
- Annual cost for rotation: €0 (water you use anyway goes from storage to daily use)
- Annual cost for tablet backup: €10–15 to replenish Micropur Forte
- Annual cost for filter inspection: €0 (check, clean, no replacement needed unless damaged)
Your initial setup cost amortizes to effectively zero after year one. This is the best return on investment of any preparedness purchase.
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