Emergency Water Storage Calculator

Water is the first thing to secure when you prepare for an outage, a storm or a boil-water notice. Enter the number of people and pets in your household and how many days you want to cover, and the calculator gives you the total volume to store and the containers you need.

Estimates for planning only. Always check equipment specifications, local codes and, for electrical work, a licensed professional.

Where the numbers come from

U.S. emergency guidance from Ready.gov recommends storing at least one gallon (about 3.8 liters) of water per person per day for drinking and sanitation, for a minimum of three days and ideally two weeks. Children, nursing mothers, sick people and anyone in a hot climate may need more. The calculator lets you choose a higher daily allowance if you also want water for cooking, washing up or basic bathing.

How to store water safely

• Use food-grade containers: commercially bottled water, food-grade jerrycans, or blue food-grade drums. Never reuse containers that held chemicals.
• Keep containers in a cool, dark place, off bare concrete, and away from fuels and pesticides.
• Replace stored tap water every six months. Commercially bottled water can be kept until its expiration date.
• Large drums are heavy — a full 55-gallon drum weighs about 460 lb (210 kg). Place it where it will be used and keep a siphon or drum pump with it.
• Have a backup way to make water safe, such as a gravity filter or unscented household bleach used according to official guidance.

Next steps: how to store water long-term and the best water filters for off-grid living.

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