Three water containers have sat empty in this garage for years. Commercial grade — bought to feel covered.

Lids on.

That part is almost funny. It's also not. Water gets filed under "nothing to worry about." The tap runs. The fridge dispenses. A delivery truck drops spring water on the porch every three weeks, like clockwork. Covered, right?

Having extra water storage really hasn't been a top priority. But if the day ever came and it was needed, not filling something as simple as an empty jug would be hard to forgive.

Daily Water and Reserve Water Aren't the Same Job

Filling with tap water is the easy part, even with that swimming-pool smell. That smell means it's already treated — most municipal water is fine to store exactly as it comes out of the faucet. Well water works too, straight from the tap at home.

Here's the trick: water goes in the container first, then an eighth of a teaspoon of plain bleach for every gallon — a little more if it's cloudy — then thirty minutes to let...