They don't give much of an explanation with the video on Fox News. It would seem that it would take a failure of the pop off valve or release valve that goes to the drip pan. Then there would have to be plugging of the incoming line which would allow pressure to force water back that way, maybe a check valve at the meter. Then it would take some pretty sturdy downstream lines that would normally fail before the tank blew. Not to mention a long period of no one turning on a hot water tap. This has to be a rare occurance, have never heard of it before. Glad I have demand water heaters but we still have tanks in Colorado and east Texas homes that remain off when no one is there.
