San Francisco, CA Environmental Rules: Erosion Control (2026)

Section J109, titled Drainage and Terracing, carries the rule that matters most for property owners. 5 applies to areas surfaced with asphalt, concrete, or other paving of similar imperviousness, so it keys on how impervious the surface is rather than what the material is called. 58 m2), and the word total means paved patches are added together: separate stretches of driveway, patio, and walkway on the same property count toward the same 200 square feet. Once past the threshold, drainage must run directly to a public sewer or storm drain.

The section covers casual water as well as stormwater, and it prohibits directing flow onto adjacent property or onto public sidewalks, so a driveway graded to sheet across the sidewalk fails the section even in ordinary rain. Permit mechanics are folded into the building process: grading that is incidental to construction under a valid building permit on a single lot needs no separate grading permit, and its cost is folded into the building valuation instead. Where grading fees do apply, § J112 bases them on earthwork volume. The Department of Building Inspection enforces the appendix, and a drainage violation is enforceable as a Building Code violation.