A plumber is preparing to rough-in a double-bowl kitchen sink with a garbage disposal unit in one of the bowls. The local plumbing code specifies a trap arm maximum length of 1.5 metres from the trap weir to the vent. Given the sink configuration, which drainage component connection is most critical to ensure proper venting and minimize sudsing?

Question: A plumber is preparing to rough-in a double-bowl kitchen sink with a garbage disposal unit in one of the bowls. The local plumbing code specifies a trap arm maximum length of 1.5 metres from the trap weir to the vent. Given the sink configuration, which drainage component connection is most critical to ensure proper venting and minimize sudsing?

Answer options:

• Connecting the disposal directly to the main stack.
• Installing an air admittance valve (AAV) for the disposal arm.
• Running a separate trap arm and vent for each sink bowl and the disposal. ✅ Connecting the disposal to a continuous waste fitting with a single trap for both bowls.

Correct answer: Connecting the disposal to a continuous waste fitting with a single trap for both bowls.

Explanation: Connecting the disposal to a continuous waste fitting provides a common drainage path before the single trap, allowing both fixtures to be vented by a single trap arm, which is a common and code-approved method for double sinks. Running separate traps and vents for each component is unnecessary and overly complex. While AAVs can be used, standard continuous waste with adequate venting is often preferred.