Warning: Spoiler! (Click to show)
I was surprised too -- guess city water pressure is high enough to pump a lot of water in a short time (we might have been gone 2.5 hours, but I could not say when the pressure fitting popped). When I came in the front door I could see water running along the kitchen floor (kitchen is at the back of the house); once in the kitchen I could see it pouring out of the cupboards under the sink like a waterfall. I sloshed down the stairs to the basement furnace room where the water shut-off was located and turned it off. The drywall-popcorn ceiling of the basement had already collapsed in several places and was distended like a balloon in others -- it was "raining" in the basement. The only room unaffected on the main floor was the garage-reno family room.
The good news was that the previous owners of the house had installed some retardedly expensive hardwood flooring in the kitchen and hallways, so the replacement value on the insurance claim gave us the money to go door-to-door-to-door (front, back patio, side) with a nice Italian tile all through the kitchen, powder room and all hallways. I could never figure out why anybody would put hardwood flooring in a room with a door to a pool? We went with engineered hardwood in the dining room and living room. We also replaced the basement wall-to-wall carpet with laminate. The whole process was a damned nuisance (we spent a week in a hotel while the tile was installed) but everything is actually better now than it was before.
The insurance adjuster said he sees a lot of these sorts of floods from those fancy fridges with the water dispensers -- if you have one of those, I recommend you have a plumber check the integrity of the fittings.