Fountain Valley, CA Accessory Structures: ADU Impact Fees (2026)

Fountain Valley Municipal Code § 21.08.055(a)(16) and (b)(21) put a floor and a formula on the impact fees the City of Fountain Valley can charge for accessory dwelling units. The fee can be imposed only on an ADU of 750 square feet or larger, so a smaller unit pays none. The fee has to be charged proportionately in relation to the square footage of the primary dwelling unit. The section prints no dollar amount, so the rate itself comes from the city's separate fee schedule.

The code borrows two state definitions. An "impact fee" has the same meaning as the term "fee" in subdivision (b) of Section 66000 of the California Government Code, and it also includes fees specified in Section 66477. It does not include any connection fee or capacity charge charged by a local agency, special district or water corporation, so those charges are treated separately.

The utility rules differ by ADU type. For an ADU created inside an existing structure, subsection (a)(10) says the city cannot treat it as a new residential use when calculating connection fees or capacity charges for water and sewer, and cannot require a new or separate utility connection. For a new construction ADU, subsection (b)(20) lets the city require a separate utility connection and charge a connection fee or capacity charge proportionate to the burden of the unit, based on its square feet or its drainage fixture unit values under the Uniform Plumbing Code. That charge cannot exceed the reasonable cost of providing the service. An ADU built together with a new single-family dwelling is treated as a new residential use for those utility charges.