Can we sue the city govt for approving plumbing work not to code?

We are the 2nd owners of our house. The house is only 4 years old. We recently found mold damage in the master bathroom. We thought it was because the shower was leaking. After my husband tore out the shower, we discovered that the shower was never plumbed. The water was going through an unsealed hole in the plywood, emptying under our house. There is no evidence of the shower ever having been plumbed. There is no pipe. All other plumbing is fine. Now, our master bathroom needs to be completely replaced and our homeowner's insurance doesn't cover it. Can we sue the city since the house ped inspection when it was built?