Fixtures & Water HeatersQuestion 213 of 360

A residential dishwasher discharge must be protected against backflow. Which method is an approved way to do this?

a.connect the drain hose to the floor
b.run the hose in a straight downhill line
c.install a check valve only
d.an approved dishwasher air gap fitting, or a high loop where permitted

Explanation

A dishwasher drain must have an air gap to prevent waste water from siphoning back into the machine. An approved air-gap fitting mounted at the counter is the standard method; a high loop is accepted in some jurisdictions. A simple check valve alone is not adequate backflow protection.

Law Reference: 2022 California Plumbing Code (CPC) §807.3

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