calif pilot,
I don't know about wrong when it comes to plumbing but here's something from my county health folks
Date: August 8, 2005 Decision No. 05-001
Subject: Dishwasher Drainage Discharge Piping and Airgap (Johnson Tee)
Code / Section: 2003 UPC 807.4
Decision. The PVC extension of the Johnson Tee dishwasher drainage airgap may be extended to interior or exterior locations for the purpose of providing air to prevent backsiphonage. When extended to the outdoors, they shall not extend to an upper level, nor shall they extend to an exterior wall of another unit in multi-family construction. When extended to the interior, they shall terminate within the same room as the dishwasher. Solvent cement meeting ASTM D3138 may be used for the transition from ABS to PVC in a non-pressure application. Where the termination is extended to a location away from the Johnson Tee, no portion of the extension shall be trapped and horizontal runs exceeding 12-inches shall be installed with a minimum of ¼-inch per foot slope back to the Johnson Tee.
The pressurized discharge piping to a Johnson Tee drainage airgap fitting may be of copper or CPVC. Other materials may be used if approved for such use by the piping manufacturer and where the fittings do not reduce the internal bore of the piping. The drainage airgap fitting shall be located in the same room as the dishwasher.