Emergency Water Storage Calculator

FEMA and the CDC recommend storing at least 1 gallon of water per person per day for drinking, cooking, and basic hygiene. This is the minimum — in hot climates, for pregnant/nursing individuals, or for those with medical conditions, you should store 2+ gallons per person per day. A 3-day supply is the absolute minimum; a 2-week supply is strongly recommended for comprehensive emergency preparedness.

Commercially bottled water typically has a shelf life of 1–2 years if stored properly in a cool, dark place. Tap water stored in clean, food-grade containers should be replaced every 6 months. You can extend this to 1 year by using water preservation drops (unscented liquid chlorine bleach — 8 drops per gallon, or use commercial water treatment products). Always check for cloudiness or odd smells before use.

The best containers are food-grade plastic containers (look for HDPE #2 plastic), specifically designed for water storage. Options include: 5-gallon food-grade buckets with tight-sealing lids, 55-gallon drums (for large families), 1-gallon jugs, and commercially sealed bottled water. Avoid used milk jugs (hard to clean, degrade quickly), non-food-grade containers, and anything that previously held chemicals or fuels. Glass containers work for small quantities but are heavy and breakable.

Absolutely! Pets need water too. A small cat or small dog needs about 0.2–0.3 gallons per day. Medium-sized dogs need about 0.5 gallons per day, and large dogs may need 0.8–1 gallon per day. In hot weather, double these amounts. Don't forget to include your pets in your emergency water calculations — they're family members too.

For long-term storage, use unscented liquid chlorine bleach (5.25%–6% sodium hypochlorite). Add 8 drops per gallon of clear water (16 drops if water is cloudy). Stir and let stand for 30 minutes — you should smell a faint chlorine odor. Alternatively, use commercial water treatment drops following package instructions. Always use food-grade containers, fill them completely to minimize air exposure, and store in a cool, dark location away from direct sunlight.

In emergency water planning, the 1-gallon-per-person-per-day recommendation is typically broken down as: ~0.5 gallons for drinking (hydration is critical), ~0.25 gallons for cooking (rehydrating food, boiling), and ~0.25 gallons for basic hygiene (hand washing, tooth brushing, sponge bathing). Water for flushing toilets is separate and not included — you can use greywater or stored non-potable water for that purpose if needed.

Pool water can be used for hygiene and flushing toilets but should NOT be used for drinking — the chlorine and chemical levels are too high and can cause illness. Rainwater can be collected and used, but it must be properly filtered and treated (boiling, chlorine treatment, or high-quality filtration) before drinking. Both are excellent supplementary sources for non-potable uses in an emergency, reducing the strain on your stored drinking water.

Water storage space adds up quickly: 1 gallon occupies about 0.13 cubic feet. So 100 gallons needs roughly 13 cubic feet — about the size of a small chest freezer. A 55-gallon drum takes up about 7.3 cubic feet (roughly 2ft × 2ft × 2ft). For a family of 4 storing a 2-week supply (56 gallons), you'll need about 7.5 cubic feet. Stackable 5-gallon containers are space-efficient and can fit under beds, in closets, or in basement corners.