How Much Water to Store Per Person
Water is the most critical resource for emergency preparedness. While you can survive weeks without food, you cannot survive more than a few days without water. The question of how much to store seems simple, but the answer depends on many factors unique to your situation.
The standard recommendation from emergency management agencies is one gallon per person per day for drinking and basic sanitation. However, this baseline often underestimates real needs, especially in hot climates, for active individuals, or when you factor in cooking, cleaning, and pets.
This guide will help you calculate a realistic water storage target for your household, understand the factors that affect your needs, and develop a practical plan for building your water reserves over time.
The One Gallon Per Day Baseline
Emergency management agencies like FEMA recommend storing at least one gallon of water per person per day. This breaks down to approximately half a gallon for drinking and half a gallon for food preparation and basic hygiene. For a minimum three day supply, that means three gallons per person.
This baseline assumes normal temperatures, minimal physical activity, and access to some alternative water sources after the initial emergency period. It represents survival quantities, not comfort quantities. Most people find they need significantly more water when actually living through an emergency.
A more realistic planning figure for extended emergencies is 1.5 to 2 gallons per person per day. This allows for more thorough hygiene, cooking flexibility, and a margin for spillage or contamination. For a two week supply using this higher estimate, you would need 21 to 28 gallons per person.
Factors That Increase Water Needs
Climate and Temperature
Hot weather dramatically increases water consumption. In temperatures above 90 degrees Fahrenheit, your body can lose two to three quarts of water per hour through sweating during physical activity. Even sedentary people in hot environments need 50 to 100 percent more water than the baseline recommendation.
If you live in a hot climate or are planning for summer emergencies, increase your storage target to at least two gallons per person per day. During heat waves without air conditioning, you may need even more.
Physical Activity Level
Emergency situations often require more physical work than normal daily life. You might need to clear debris, walk long distances, or perform manual tasks that would normally be done with electricity. Active individuals can easily require double the baseline water amount.
Health Conditions
Certain health conditions increase water needs significantly. Nursing mothers require additional fluids. People with diabetes, kidney conditions, or those taking certain medications may need more water. Illness involving fever, vomiting, or diarrhea can cause rapid dehydration requiring much higher fluid intake.
Children and Elderly
Children and elderly family members may have different hydration needs. Children often do not recognize thirst signals as readily and may need reminders to drink. Elderly individuals may have reduced thirst sensation and can become dehydrated without realizing it.
Pets
Do not forget to include water for pets in your calculations. Dogs generally need about one ounce of water per pound of body weight per day. A 50 pound dog needs roughly half a gallon daily. Cats need about 4 ounces per 5 pounds of body weight.
Calculating Your Household Needs
Start by listing every person and pet in your household. Assign each person a daily water need based on the factors discussed above. Here is a practical calculation method:
Base amount: 1 gallon per adult per day
Hot climate adjustment: Add 0.5 to 1 gallon
Active lifestyle: Add 0.5 gallon
Health conditions: Add 0.5 gallon
Children under 12: 0.5 to 0.75 gallon per day
Pets: Calculate based on weight
Multiply your daily total by the number of days you want to prepare for. Most experts recommend a minimum two week supply for serious preparedness planning. A month supply provides substantial security for extended disruptions.
Example Calculation
Consider a family of four in a moderate climate: two adults, one teenager, and one child age 8, plus a medium sized dog.
Daily needs: 2 adults at 1.5 gallons each equals 3 gallons. One teenager at 1.25 gallons. One child at 0.75 gallon. One 40 pound dog at 0.3 gallon. Total daily need is approximately 5.3 gallons.
For a two week supply: 5.3 gallons times 14 days equals 74 gallons. Rounding up to 80 gallons provides a reasonable safety margin.
Storage Duration Goals
Three Day Supply: Minimum Starting Point
This is the bare minimum recommended by FEMA for basic emergency kits. Three days covers most short term power outages and minor disruptions. However, this provides almost no margin for extended emergencies.
Two Week Supply: Recommended Baseline
Two weeks of water storage handles most regional emergencies, including extended power outages, water main breaks, and contamination events. This duration allows time for municipal water systems to be restored or for help to arrive.
One Month Supply: Enhanced Security
A month of stored water provides significant peace of mind and handles more severe scenarios like infrastructure damage from natural disasters. This level requires more storage space but offers substantial security.
Beyond One Month
For very extended emergencies, stored water alone becomes impractical. At this point, focus shifts to water sourcing and purification capabilities rather than trying to store everything you might need.
Storage Space Considerations
Water is heavy and bulky. One gallon weighs about 8.3 pounds. A two week supply for one person at 1.5 gallons per day weighs over 170 pounds. Space planning is essential.
Standard 5 gallon water containers are popular because they balance capacity with portability. A filled 5 gallon container weighs about 42 pounds, which most adults can lift and move. Larger containers like 55 gallon drums are more space efficient but cannot be moved when full without equipment.
Consider distributed storage throughout your home. Rather than keeping all water in one location, store containers in multiple areas. This provides redundancy if one area becomes inaccessible and distributes the weight load across your floor.
Building Your Supply Gradually
You do not need to achieve your storage goal immediately. Building water storage over time is more financially manageable and allows you to learn proper storage techniques.
Week 1 to 2: Start with commercial bottled water for immediate needs. Purchase enough for a three day supply.
Month 1: Add food grade water containers and fill them from your tap. Treat with water preserver if desired.
Month 2 to 3: Expand to one week supply. Begin establishing rotation schedule.
Month 4 to 6: Reach two week supply goal.
Ongoing: Maintain and rotate. Consider expanding to one month.
Quick Reference Checklist
- Calculate daily water needs for each household member
- Include water for all pets
- Adjust for climate and activity level
- Set a storage duration goal (minimum two weeks recommended)
- Plan storage locations throughout home
- Choose appropriate container sizes
- Establish a rotation schedule
- Consider water purification backup methods
Frequently Asked Questions
How long can I store tap water?
Tap water stored in clean, food grade containers in a cool, dark place can remain safe for 6 months to one year. Adding commercial water preserver can extend this to 5 years. Rotate regularly regardless of treatment.
Should I store more water if I have a water filter?
Water filters and purification methods are excellent backup capabilities, but they require a water source to filter. Store enough water to be independent of outside sources, then consider filters as supplementary capacity.
Can I count other beverages toward my water storage?
Stored juices, sports drinks, and other beverages can supplement water storage but should not replace it. Water is more versatile for cooking, cleaning, and medical needs. Coffee and tea can contribute to hydration but require water to prepare.
What about water in my hot water heater?
Your hot water heater typically holds 30 to 50 gallons of potable water. This is an excellent emergency reserve, but requires knowing how to safely drain it when utility power is out. Learn the procedure before an emergency.
How do I store water in an apartment with limited space?
Use under bed storage containers, closet floor space, and stackable containers. Consider flat water containers designed to slide under furniture. Quality over quantity: a smaller, well maintained supply beats a larger neglected one.
Is it worth storing water if I have a well?
Yes. Wells require electricity to pump water in most modern installations. Without power, you cannot access your well water without manual pumping equipment. Store enough water to bridge the gap until power returns or you can implement alternative pumping.