And then there's the eight portable toilets with pop-up privacy tents.

"You can't have 1,500 people not able to go to the bathroom," said Marsha Hierbaum, president of the Bel Air Crest Homeowners Assn.

The shed represents one piece of a years-long effort to ensure all residents of this gated community are ready when the "Big One" hits. In a city populated by people expecting — but many ill-prepared to handle — a major earthquake, it is the affluent and organized hillside neighborhoods that have taken emergency preparedness to the extreme. A 6.0-magnitude earthquake that rumbled through Napa last month underscored for some how important their effort is.

Local residents have long understood that living on winding, narrow roads means they could be on their own when disaster strikes. So they have taken safety into their own hands.

Although Bel Air Crest has fewer than 300 homes, the homeowners association has spent about $50,000 on emergency supplies and equipment over the last three years, including the purchase of a 2,000-gallon water truck.