01 — The baseline number
One gallon per person per day is the floor, not the goal
The CDC, FEMA, and the American Red Cross all use the same baseline: one gallon of water per person per day. That figure covers drinking (roughly half a gallon) and basic sanitation including cooking and minimal hygiene (the other half). It is a survival number, not a comfortable living number.
One gallon per day assumes no showering, no laundry, minimal cooking, and no margin for spillage or illness. The CDC's guidance explicitly recommends building toward a two-week supply and notes that people in hot climates, those doing physical work, nursing mothers, and people who are sick may need significantly more.
A practical household target is two gallons per person per day. This provides a realistic margin for cooking, basic hygiene, and the unexpected. For a two-week supply, that works out to 28 gallons per person, or 112 gallons for a family of four.
| Household size | 3-day minimum (1 gal/day) | 2-week target (2 gal/day) |
|---|---|---|
| 1 person | 3 gallons | 28 gallons |
| 2 people | 6 gallons | 56 gallons |
| 4 people | 12 gallons | 112 gallons |
| 4 people + large dog | 13.5 gallons | 119 gallons |
02 — Use priorities
What to use water for first when supply is limited
When water is scarce, the order of priority matters. Drinking comes first. Dehydration sets in faster than most people expect, and it impairs judgment at exactly the moment good judgment is most needed.
After drinking, cooking and food preparation rank second. Rehydrating freeze-dried or dehydrated food, washing hands before handling food, and cleaning cooking surfaces all require water, and skipping these steps creates health risk.
Basic hygiene comes third. Hand washing, particularly after using the toilet and before eating, prevents illness from spreading through a household. Bathing and laundry sit at the bottom of the priority list during a genuine shortage. Ready.gov notes that children, nursing mothers, and people who are sick may have elevated water needs that should be factored into allocation before general household hygiene.
03 — Water weight
Weight is the practical constraint most households underestimate
One gallon of water weighs 8.34 pounds. This is not a trivial figure. A 5-gallon container full of water weighs approximately 41.7 pounds. A 55-gallon barrel weighs roughly 459 pounds when full, which means it cannot be moved after filling and must be placed in its permanent location first.
Weight affects where water can be stored safely. An upper floor, a weak shelf, or a surface not designed for concentrated load can fail under the weight of a large water supply. Ground-floor storage, basements, and garage slabs are better choices than elevated shelving. For a two-week supply of 112 gallons, a family of four is managing about 935 pounds of water.
Smaller containers, typically 5 to 7 gallons, are easier to move and rotate but require more containers for the same total volume. The tradeoff is practical: many households combine a few large containers for volume with smaller containers for flexibility and rotation.
04 — Rotation
Stored tap water should be rotated every six months
CDC guidance specifies that tap water stored in food-grade containers should be replaced every six months. The water itself does not expire, but the chlorine added to municipal water dissipates over time, removing its antimicrobial protection. Containers also slowly off-gas, and temperature fluctuations can introduce contaminants.
The rotation date should be written on every container at the time of filling. Many households tie rotation to a twice-yearly reminder, such as when clocks change for daylight saving time, or to seasonal maintenance routines. The used water is not wasted: it can go to outdoor plants, lawn irrigation, or cleaning tasks.
Commercially bottled water carries manufacturer-stamped dates, typically one to two years out. These dates reflect plastic integrity and taste quality more than microbial safety, but they are a useful rotation benchmark. Containers stored in cool, dark conditions at 50 to 70 degrees Fahrenheit, away from direct sunlight and away from chemicals such as gasoline or pesticides, will maintain quality longest.
Quick reference
- Store at least 1 gallon per person per day; target 2 gallons for realistic comfort
- Aim for a 2-week supply, not just 72 hours
- Add extra for pets, nursing mothers, hot climates, and anyone who is ill
- Prioritize water in this order: drinking, cooking, hand washing, then all other hygiene
- One gallon weighs 8.34 pounds; plan storage locations before filling large containers
- Rotate tap water in food-grade containers every 6 months; label each container with its fill date
- Store containers at 50 to 70 degrees F, away from sunlight and chemical fumes
Primary sources
- CDC — How to Create an Emergency Water Supply: Baseline of 1 gallon/person/day, 2-week goal, 6-month rotation for tap water, food-grade container requirements, storage temperature of 50–70 degrees F.
- Ready.gov (FEMA) — Water: Confirms 1-gallon minimum, notes elevated needs for children, nursing mothers, sick individuals, and hot climates; recommends never rationing drinking water unless ordered by authorities.
- FEMA — Food and Water in an Emergency: Use priority hierarchy (drinking before sanitation), container preparation guidance, bleach treatment for non-chlorinated sources.