Fixtures & Water HeatersQuestion 208 of 360

The minimum required air gap between a fixture's water supply outlet and the fixture's flood-level rim protects against:

a.water hammer
b.thermal expansion
c.backflow of contaminated water into the potable supply
d.scalding

Explanation

An air gap is a vertical space between the supply outlet and the flood-level rim of a fixture that prevents contaminated water from being siphoned back into the potable system. It is the most reliable backflow protection. The minimum gap depends on the outlet size and nearby walls.

Law Reference: 2022 California Plumbing Code (CPC) §603.3.1

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