Duplex plumbing issue not covered

[Daniel Ziner]

Good morning everyone.  Wanted to see what your thoughts are on this.  I closed on a duplex a few month ago and now there is a plumbing issue where the plumber says that they'll need to change both main lines to the house and reroute the piping since it's all leaking.  He said it will cost $12,335.  I got the house inspected and in the inspection report it never mentioned the standing water so it was for sure leaking prior to closing.  I am going through the warranty company that the inspector has, but they said they will only cover a small amount of the repair.  Any advice moving forward would be appreciated.  Thanks!