I had that a few years ago. My house is on a slab and the pipes were under the slab. I never go into the back part of my house, so I have no idea how long the water was running back there, but one day I noticed the sound of water running through the pipes. I went all around outside looking for a sprinkler I might have left on and couldn't find one. I finally went into the Crystal Shining Bathroom to see if maybe that toilet hadn't seated last time it was flushed and the bathroom had about an inch of water all over the floor. The back bedroom (the doll room) was totally flooded, and a small portion of the bedroom used as a library was flooded. Come to find out the hot water pipe under the cement slab had rusted through.
Lucky for me, the insurance paid a goodly portion of the 'fix.' I don't remember what the cost was. The clean-up company took up my fairly new wall to wall carpet to mop up the water, then ran fans for a week or so to get the carpet dried out. It was a very traumatic experience for me because at that time I was very house proud (my pre-Misty days, when I took excellent care of the carpet).
Sounds awful!!
We were very fortunate that it didn't burst.
It could have been way worse.
Now we just need to put up a few sheets of drywall and paint.
We are lucky our pipes don't run under the slab. I think they changed that in the 70's. I could be wrong.