Four people × 1 gallon × 3 days = 12 gallons. That is the minimum emergency water buffer for a household of four; CDC says to aim for two weeks when possible, and to store extra for pregnancy, illness, pets, or hot weather. 12

Use unopened commercially bottled water when you can. For filled containers, choose FDA-approved food-grade containers, label the fill date, keep them cool and out of sunlight, and replace the water every six months. 2

If the tap is unsafe, use bottled, boiled, or treated water. Boil clear water for 1 minute, or use unscented 5%–9% sodium hypochlorite bleach at 8 drops per gallon and wait 30 minutes. Cloudy, murky, colored, or very cold water needs double the bleach amount. Water containing fuel or toxic chemicals cannot be made safe by boiling or disinfecting. 3

The boring win: put 12 gallons in one known spot, write the date on it, and set a six-month reminder. Future-you will be grateful—and mildly impressed by the label maker.