Arcadia, CA Landscaping Rules: Rainwater Harvesting (2026)

Section 7554.9 is the rainwater retention section of the City's Water Efficient Landscaping ordinance. Subsection A encourages stormwater best management practices in the landscape and grading design plans to minimize runoff and increase on-site rainwater retention and infiltration. Subsection C is the mandate: all planted landscape areas are required to have friable soil to maximize water retention and infiltration, with a cross-reference to Section 7554.4.A.3.

Subsection D strongly recommends capture and infiltration capacity sufficient to prevent runoff from impervious surfaces such as roof and paved areas from either the one inch, 24-hour rain event or the 85th percentile, 24-hour rain event, plus additional capacity as required by any applicable local, regional, state or federal regulation. Subsection E recommends grading driveways during construction to drain to vegetated areas, minimizing impervious area, porous surfaces, directing roof and paved runoff into planting beds, rain gardens, cisterns and other rain harvesting or catchment systems, infiltration beds, swales, basins and drywells, and constructed wetlands.

Design plans have to show what is built. Section 7554.4.B.10 requires the landscape design plan to identify location, installation details and 24-hour retention or infiltration capacity of any applicable stormwater best management practices, and Section 7554.4.B.11 requires it to identify any applicable rain harvesting or catchment technologies and their 24-hour retention or infiltration capacity. Section 7554.6.B.1.e adds stormwater retention improvements, if applicable, to the landscape grading plan.

Definitions and hard numbers sit in the stormwater chapter. Section 7810(41) defines Rainfall Harvest and Use as a LID BMP system designed to capture runoff, from a roof or elsewhere within the site, and hold it in temporary storage until the harvested water can be used for irrigation or non-potable uses. Potable use requires a system with disinfection treatment that is approved for such use by the local building department. For Planning Priority Projects, Section 7828 requires runoff control through infiltration, evapotranspiration, bioretention and/or rainfall harvest and use, and retention on site of the Stormwater Quality Design Volume, defined as the runoff from the 85th percentile 24-hour event or from a 0.75 inch, 24-hour rain event, whichever is greater.

Small lots get a shortcut. Section 7554.3.C sends any lot with less than 2,500 square feet of landscape that meets its entire water requirement with graywater or stored rainwater captured on site to the prescriptive compliance option in the City's Water Efficient Landscaping Documentation Package and Guidelines.