True or False: A commercial dishwasher's discharge may connect directly to a sink tailpiece or disposal without an air gap or air break, provided the drain line downstream is metal rather than plastic.
Not quite. The answer is B: False
Washington's text requires commercial dishwashing machines to discharge indirectly through an air gap — and domestic machines through an air gap fitting into a receptor, a wye on a sink tailpiece, or a disposer connection. The hazard is dirty dishwater siphoning back into the machine if the sink or disposal backs up, so the pipe material downstream has no bearing on whether an air gap is needed.
Reference: WAC 2021 51-56-0400, §414.3 (Dishwashing machine drainage connection)
Checked against the official text
Trade Code Wizard is not affiliated with, endorsed by, or licensed by the International Code Council (ICC), the National Fire Protection Association (NFPA), IAPMO, the ESCO Institute, NATE, HVAC Excellence, NASCLA, NICET, the U.S. Environmental Protection Agency, PSI, Prov, Pearson VUE, or any state or local licensing board. Exam and code names are used only to identify which examination this study material prepares you for.
These are original practice questions written to publicly published exam content outlines. They are not actual exam questions, and they do not reproduce code text. Explanations cite code sections and state requirements in our own words — always verify against the code edition your jurisdiction has adopted, which may differ from the edition cited here.
Passing is not guaranteed. This is study material, not a substitute for the adopted code, for your licensing board's requirements, or for qualified instruction.