The rule: one gallon per person per day, minimum. Half for drinking, half for cooking and basic hygiene. Pets count — roughly a gallon a day for a large dog, less for cats.
The family math
- 2 people × 3 days = 6 gallons
- 4 people × 3 days = 12 gallons
- 4 people × 2 weeks (the at-home target) = 56 gallons
Fifty-six gallons sounds impossible until you realize you don't have to store it all — you need some stored, plus a way to make more water safe.
The water already in your house
Your water heater holds 30–50 gallons. To use it safely: turn off the power or gas to the tank first, let it cool, then drain from the bottom valve. Ice in the freezer, and the water in your pipes (open the highest tap in the house, then drain from the lowest) add more. Skip the toilet tank if it's chemically treated, and never drink pool water — cleaning only.
Four ways to make water safe
- Boil — one minute at a rolling boil kills germs. The gold standard, but it needs heat and doesn't remove chemicals.
- Filter — a hollow-fiber filter like the Field Straw removes bacteria and protozoa (not viruses — no portable filter of this class does). A gravity system like the Basecamp does it by the gallon on your counter, no power needed.
- Tablets — light, shelf-stable, slow. The backup layer for any go-bag.
- Bleach — 8 drops (1/8 teaspoon) of plain unscented 5–6% bleach per gallon, wait 30 minutes. Write the recipe on the bottle now.
The full worksheet — storage targets, safe sources, and the family plan — is in the free Family Water Plan, which ships with every water order.