You learn the difference between drinking water and bathing water.

Everyone should have on hand, food for a couple of days that are shelf stable - and rotate them. For most folks - that would be cans of soups / stews / chili, canned fruit, crackers, peanut (or other nut) butter. Just think of protein, fruits and vegies. And water. Don't forget the drinking water. A source to heat besides your normal utilities, although just because the way it's delivered, if you have natural gas - you will probably still have it in bad weather. In an earthquake, all bets are off. And if you smell gas, don't light a match.