Performed a leak search and found a cabinet screw through the 3 inch pvc drain pipe on main level at the wet bar. Removed the screw behind the cabinet and found it wet and rusted. Determined that the leak was coming that there. Homeowner said that they will contact a remediation company to remove the cabinet to give us better access to perform a rapair in the future. Homeowner will not use upstairs bathroom until the leak is repaired.