What happens when the water runs out

People last longer without food than without water, and a house notices the difference on the second day. Headache, short temper, a kid who won't stop asking. By the time someone is dizzy, you are already late. The gallon-a-person-a-day rule exists so the list shows a number big enough to matter: two people for three days is six gallons, four people for a month is 120. A crate that looks like plenty on a product page is often one afternoon.

The gallon is drinking and washing hands. It is not a shower. Skip the washing and a stomach bug moves through a house that is stuck in one place, sharing the same cups. That illness uses up more water than the thirst did. If someone is sick, or there's a baby, or the heat is bad, the printed gallon is already short.

A lot of stored food needs water you add yourself. If the gallons were counted only for drinking, those meals don't get made. The food is in the closet and nobody can eat it.

The other failure is water you shouldn't drink

After a flood, or when the utility says the tap is off, people get tempted by the creek, a bucket from the garage, or a jug that used to hold something else. Fuel and sewage will not be fixed by a camping filter. The filter on a two-week or 30-day kit, and on any storm kit, is for water you didn't store that is still ordinary water. Households of five or more get two, because one pump and a line of people is how someone gives up and drinks the wrong thing.

Use jugs made for drinking water, keep them off the paint and the gasoline, and write the fill date on the side. A split milk jug in a hot closet is how a careful plan turns into a smell and an empty shelf. If you can't carry the pile, you won't rotate it, and next year the "full" water is the old water.