Water is the most important resource for survival when infrastructure fails or a natural disaster strikes. The human body is approximately 60% water, and biological functions cease quickly without adequate hydration. While a person can survive for weeks without food, the limit for survival without water is typically only a few days. This immediate and non-negotiable need for clean water makes storing a proper emergency supply the absolute priority in preparedness planning.
Calculating Your Minimum Supply
The baseline recommendation for emergency preparedness is to store a minimum of one gallon of water per person per day. This quantity covers essential drinking needs and minimal food preparation requirements during an acute emergency. Generally, half a gallon is allocated for direct consumption, which is the minimum amount a normally active adult needs in a temperate environment.
The federal recommendation for a household’s stored supply is a minimum of three days, though a two-week supply is suggested as a more robust goal for prolonged outages. To calculate your minimum three-day supply, multiply the number of people in your household by three gallons. For example, a family of four requires a minimum of 12 gallons of water.
This three-day supply serves as a stopgap until external aid arrives or alternative water sources can be secured and treated. Planning for a longer duration, such as a two-week supply (14 gallons per person), provides a greater margin of safety during a widespread infrastructure failure. A family of four requires 56 gallons for two weeks.
Variables That Increase Consumption
The baseline one-gallon per day calculation represents a minimum requirement under ideal circumstances, but several factors necessitate increasing this stored amount. Environmental conditions significantly impact fluid loss; people in hot climates will lose more water through perspiration. In very hot conditions, it may be necessary to double the standard daily allocation to two gallons per person to mitigate the risk of heat-related illness and dehydration.
Physiological states also elevate daily water needs. Nursing mothers and pregnant individuals require higher fluid intake to support their own metabolic functions and the needs of a child. People who are ill, particularly those suffering from vomiting or diarrhea, experience rapid fluid loss and must have extra water for rehydration.
Intense physical activity, which may be unavoidable during an emergency response or evacuation, also increases the demand for water. The increased metabolic rate and sweating associated with exertion necessitate a greater volume of replacement fluid to maintain the body’s electrolyte balance. It is wise to store an additional buffer of water for each person in the household.
Essential Water for Non-Drinking Needs
While drinking water is the primary concern, a portion of the stored supply must be reserved for basic hygiene and sanitation to prevent the spread of disease. Using water for hand washing, especially after using the toilet or before preparing food, is a non-negotiable public health measure. The standard one-gallon per day already accounts for minimal sanitation, such as brushing teeth and washing hands.
Additional water is necessary for the limited preparation of non-perishable food items, such as rehydrating freeze-dried meals or preparing infant formula. If resources are severely limited, designate a portion of the stored water as non-potable for uses like flushing toilets. This requires a separate, clearly labeled supply to avoid accidental consumption. The World Health Organization suggests that 10 liters per person per day allows for comfortable provision for basic cooking and hygiene needs.
Safe Storage Logistics
Properly storing your emergency water supply ensures its long-term safety and palatability. Water should only be stored in food-grade containers, such as high-density polyethylene (HDPE) or stainless steel, that do not leach harmful chemicals. Avoid using containers that previously held non-food liquids, like bleach bottles, as they can retain residues that contaminate the water or promote bacterial growth.
Containers filled at home with tap water should first be thoroughly cleaned and sanitized, often with a mild solution of unscented household chlorine bleach, before being filled completely. Stored water should be kept in a cool, dark location, ideally between 50°F and 70°F, and away from direct sunlight or toxic substances like gasoline or pesticides. This placement prevents the degradation of plastic containers and inhibits the growth of microorganisms.
The stored water supply must be rotated on a schedule to maintain quality, as even sealed water can develop an off-taste over time due to the container material. Water stored in home-filled containers should be replaced every six months. Commercially bottled water can last longer and should be checked against its expiration date. Rotation ensures the water is fresh and safe when the time comes to rely on it.