Drainage, Waste & VentQuestion 142 of 360
A domestic dishwasher discharge, before it connects to the drainage system, must be protected against backflow by…
a.a backwater valve
b.an air gap (or an approved high loop where permitted) in the drain line
c.a check valve at the pump
d.a deep-seal trap
Explanation
A dishwasher drain must be protected by an air-gap fitting, or by a high loop where the local code allows, so waste cannot siphon back into the machine. The air gap is the most reliable method and is required by many jurisdictions. This protects the dishwasher and the food washed in it from contamination.
Law Reference: 2022 California Plumbing Code (CPC) §807.0Practice all 360 questions free — no signup required.
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