How much water should you store for an emergency, and how do you calculate household water needs?
Store at least one gallon of water per person per day for several days, for drinking and sanitation. A normally active person needs about three quarters of a gallon of fluid daily, and children, nursing mothers, and sick people may need more. One gallon times three days is 3 gallons for one person and 12 gallons for four people; those totals are arithmetic, and FEMA does not name three days. In very hot temperatures, FEMA says water needs can double.
Published September 22, 2026
The direct answer
Store at least one gallon of water per person per day for several days, for drinking and sanitation. A normally active person needs about three quarters of a gallon of fluid daily, and children, nursing mothers, and sick people may need more. One gallon times three days is 3 gallons for one person and 12 gallons for four people; those totals are arithmetic, and FEMA does not name three days. In very hot temperatures, FEMA says water needs can double.
Decision table
Source: FEMA and Ready.gov emergency preparedness guidelines. Guidance on determining water needs, water storage, and water treatment. The baseline standard is at least one gallon per person per day for several days. Seven-day and fourteen-day columns represent arithmetic on FEMA's daily figure, not official FEMA duration recommendations.
| Household Size | 3-day supply (arithmetic on the one-gallon daily figure, not a FEMA duration) | 7-Day Supply (arithmetic on FEMA daily figure, not a FEMA recommendation) | 14-Day Supply (arithmetic on FEMA daily figure, not a FEMA recommendation) | Basis |
|---|---|---|---|---|
| 1 person | 3 gallons | 7 gallons | 14 gallons | 1 gallon per person per day |
| 2 people | 6 gallons | 14 gallons | 28 gallons | 1 gallon per person per day |
| 3 people | 9 gallons | 21 gallons | 42 gallons | 1 gallon per person per day |
| 4 people | 12 gallons | 28 gallons | 56 gallons | 1 gallon per person per day |
| 5 people | 15 gallons | 35 gallons | 70 gallons | 1 gallon per person per day |
| 6 people | 18 gallons | 42 gallons | 84 gallons | 1 gallon per person per day |
| Guideline Attribute | Stated Guidance |
|---|---|
| Baseline water requirement | At least 1 gallon per person per day for several days |
| Daily fluid intake baseline | About three quarters of a gallon of fluid daily for a normally active person |
| Vulnerable population needs | Children, nursing mothers, and sick people may need more |
| Medical emergency reserve | Additional water may be required |
| High temperature adjustment | Needs can double in very hot temperatures |
| Rationing rule | Never ration drinking water unless ordered by authorities |
| Recommended containers | Commercially bottled water in original sealed containers, or food-grade containers |
| Sanitizing solution | 1 teaspoon unscented household chlorine bleach to 1 quart of water |
| Tap water rotation interval | Replace home-prepared water every 6 months |
| Boiling disinfection | Rolling boil for 1 full minute |
| Bleach disinfection | 1/8 teaspoon bleach per gallon of water, let stand 30 minutes |
| Food supply recommendation | At least a several-day supply of non-perishable food |
| Source | FEMA and Ready.gov emergency preparedness guidelines |
Who should pick which
Short-Term Shelter-in-Place
For short-term shelter-in-place events, households should prepare to meet FEMA's baseline of several days by storing at least a 3-day supply (1 gallon per person per day).
Extended Disruptions
For extended disruptions or areas vulnerable to prolonged infrastructure outages, households should calculate 7-day or 14-day storage targets using the same 1-gallon daily rate per person.
Who Needs More Than the Minimum
Households with children, nursing mothers, sick family members, or residents in very hot temperatures may need more, as FEMA notes that high temperatures can double daily water needs.
What the makers do not state
Ready.gov and FEMA state “for several days” as the planning horizon. FEMA does not endorse an official 7-day or 14-day requirement. Figures for 7 and 14 days represent mathematical arithmetic based on the 1-gallon daily rate, not official FEMA duration mandates.
Ready.gov states to include “Pet food and extra water for your pet” in the emergency kit checklist, but does not provide a specific gallons-per-day numerical figure for pets.
Ready.gov recommends storing “at least a several-day supply of non-perishable food,” but does not publish a daily nutritional energy target in its published guidance.
The published guidelines do not break down water allocation into separate specific volumes for bathing, cooking, or tooth brushing beyond the unified 1-gallon drinking and sanitation guideline.
Chemical purification: FEMA explicitly states that water treatment chemicals such as iodine or products from camping stores that do not contain 5.25% to 6.0% sodium hypochlorite as the only active ingredient are not recommended.
Check current availability
Official emergency guidelines published by FEMA and Ready.gov are free public resources.
Frequently asked questions
What is the baseline water storage guideline from FEMA?
FEMA recommends storing at least one gallon of water per person per day for several days, for drinking and sanitation.
How much fluid does a normally active person need daily?
A normally active person needs about three quarters of a gallon of fluid daily from water and other beverages, with actual needs varying by age, physical condition, and climate.
How much water should a family of four store for a 3-day emergency?
A family of four requires at least 12 gallons of water for 3 days under FEMA's baseline of 1 gallon per person per day.
What are the water figures for 7 days and 14 days?
Based on arithmetic from FEMA's daily baseline, 1 person needs 7 gallons for 7 days and 14 gallons for 14 days; a family of four needs 28 gallons for 7 days and 56 gallons for 14 days. These figures are arithmetic extensions on FEMA's daily rate, not official FEMA duration recommendations.
Does FEMA recommend rationing water in an emergency?
No. FEMA explicitly states never to ration drinking water unless ordered to do so by authorities, advising people to drink the amount needed today and look for more tomorrow.
How often must home-stored water containers be rotated?
FEMA states that water that has not been commercially bottled should be replaced every six months.
How can suspicious water be disinfected by boiling or bleach?
FEMA specifies bringing water to a rolling boil for one full minute, or adding 1/8 teaspoon of regular unscented household bleach (5.25% to 6.0% sodium hypochlorite) per gallon and letting it stand for 30 minutes. If the water does not have a slight bleach odour after 30 minutes, repeat the dose and let it stand another 15 minutes.
Keep the decision in context
This guide outlines household emergency water requirements; explore our bug out bag checklist for portable water carry, filtration, and evacuation gear. To compare medical supplies and emergency packs against our curated picks, visit the medical category on The Grid.