Wow!
Thats bad. I have been in the plumbing trades since the 80's and that is prolly the worse I heard but you are fortunate is wasn't up stairs on third floor where it really get into costly repairs.

I would advise you to check with your insurance company tho. I will bet you are not thru with problems tho. Sounds like you have well water and with softner system and they must of installed thin wall "M" copper in which is not to code in Ohio but is still sold in stores like home depot and lowes. Softners can and will ruin that thin wall piping.