Water Use by Activity
| Use | Daily Amount Per Person |
|---|---|
| Drinking (minimum) | 0.5 gallon (64 oz) |
| Drinking (comfortable) | 1 gallon |
| Cooking | 0.5-1 gallon |
| Basic hygiene (sponge bath, oral, hands) | 1-2 gallons |
| Minimal sanitation | 0.5 gallon |
| Total minimum daily | 1 gallon |
| Total comfortable daily | 2-3 gallons |
Pets: Dogs approximately 1 ounce per pound of body weight per day (a 60-lb dog needs nearly 0.5 gallon/day). Cats: half that.
Quick Reference Storage Table
| Duration | 1 Person | 2 People | 4 People | 6 People |
|---|---|---|---|---|
| 3 days (minimum) | 3 gallons | 6 gallons | 12 gallons | 18 gallons |
| 1 week (FEMA) | 7 gallons | 14 gallons | 28 gallons | 42 gallons |
| 2 weeks (recommended) | 14 gallons | 28 gallons | 56 gallons | 84 gallons |
| 1 month (serious prep) | 30 gallons | 60 gallons | 120 gallons | 180 gallons |
| 3 months (extended) | 90 gallons | 180 gallons | 360 gallons | 540 gallons |
Based on 1 gallon per person per day minimum
Building Your Storage Plan
Step 1: Calculate your minimum daily requirement
Daily requirement = (People × 1 gallon) + (Pets × 0.5 gallon for a 60-lb dog, scale accordingly)
Step 2: Decide your target duration
- 3 days: Hurricane/earthquake immediate supply
- 2 weeks: FEMA recommended standard
- 1 month: Regional disruption supply
- 3 months: Serious preparedness goal
Step 3: Add comfort multiplier
Minimum (1 gallon/person/day) is for drinking and critical hygiene only — no bathing, limited cooking, no laundry. For any comfort or extended stay: multiply by 2-3.
Worked example: Family of 4 (2 adults, 2 children) + 1 medium dog, 30-day comfortable supply
- Adults: 2 × 2.5 gallons/day = 5 gallons
- Children: 2 × 2 gallons/day = 4 gallons
- Dog: ~0.5 gallon/day
- Daily total: 9.5 gallons/day
- 30-day supply: 9.5 × 30 = 285 gallons
That's approximately five 55-gallon drums.
Adjustments for Special Circumstances
Hot climate: Add 0.5-1 gallon per person per day. Sweat losses are significant in hot weather.
Physical labor: People doing heavy physical work lose 1-2 liters of water per hour of work through sweat. Plan accordingly — 1 gallon per person per day of hard labor = inadequate.
Nursing mothers: Need approximately 0.5-1 additional gallon per day for milk production.
Infants not breastfeeding: Formula preparation requires approximately 1 quart of water per day. Water quality for formula mixing must be drinking-quality treated water.
Illness: Vomiting and diarrhea require additional water for fluid replacement — oral rehydration requires 1-2 liters per episode of significant fluid loss.
Wound care: Wound irrigation requires 250-500ml per wound cleaning session.
Storage Container Sizing
| Container | Volume | Good For |
|---|---|---|
| WaterBOB | 100 gallons | Family of 4, 25-day minimum supply |
| 55-gallon drum | 55 gallons | 1 person, 55 days; family of 4, ~14 days |
| 7-gallon Aquatainer | 7 gallons | Portable; 5 containers = 35 gallons |
| 5-gallon HDPE jug | 5 gallons | Portable; 6 containers = 30 gallons |
| 2-liter commercial bottle | 0.53 gallon | Go-bags; 2 bottles/person/day |
Water Storage vs. Water Sourcing
Pure storage is expensive in volume and space. A hybrid approach is more practical:
Stored water (3-14 days): Handles immediate disruption without any sourcing activity
Filtration + purification capability: Extends any water source into safe drinking water indefinitely
Rainwater collection: Provides ongoing input to storage in applicable climates
A family with 100 gallons stored AND a quality filtration system AND access to any water source (rain, stream, neighbor's pool) has effectively unlimited water security compared to a family with only storage.
The calculation then becomes: how long can you bridge before your sourcing capability kicks in? That's how much to store.
Now find out if YOUR shelves cover this.
This guide tells you what a prepared family needs. The free calculator tells you what your family needs — by age, activity level, and timeframe.
Then track it: Salt & Prepper monitors your real inventory against the plan. $10/mo.
Sources
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