If you’ve ever read the fine print on the owner’s manual that comes with a new water heater, you may have noticed a paragraph that says something like this: You may have wondered if that’s a purely theoretical danger, or if such kitchen-sink reenactments of the Hindenburg disaster really happen. It turns out that they do. The photo at right shows the aftermath of an accident at a U.S. Navy facility in Key West, Florida, where a base housing inspector had been performing a routine inspection of an unoccupied housing unit. Minutes after she turned on the water in the kitchen sink and started the dishwasher, the machine exploded, blew across the