Riverside, CA Accessory Structures: ADU Impact Fees (2026)
Key Facts
- Fee waiver
- No City impact fees under 750 sq ft
- Fee scaling
- Proportional to primary dwelling sq ft (750+ sq ft ADUs)
- In-home ADU utility fee
- None owed (§19.442.030(J)(3))
- New detached ADU utility fee
- Proportionate to size/fixture burden
- Private sewage
- Must meet County Health Dept. standards
Summary
ADUs under 750 square feet pay no City impact fees at all in Riverside, per §19.442.030(K)(1); larger ADUs are charged proportionately to the primary dwelling's square footage instead of a flat rate, and most ADUs added to an existing home skip new water and sewer connection fees entirely.
K.Impact Fees.1.For ADUs under 750 square feet, no City impact fees shall apply.2.For ADUs 750 square feet and over, impact fees shall be charged proportionately in relation to the square footage of the primary dwelling unit. ... J.Utilities.2.ADUs shall not be considered a new residential use for the purposes of calculating connection fees or capacity charges for utilities, including water and sewer service unless the ADU is constructed with a new single-family dwelling.3.A new or separate utility connection, connection fee, or capacity charge shall not be required by the utility provider for an ADU located within the existing primary dwelling unit.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Code of Ordinances: Supplement 33).
Full Breakdown
030(K) sets Riverside's ADU impact-fee structure in two tiers. Any ADU under 750 square feet pays no City impact fees whatsoever, the exemption applies regardless of whether it's attached or detached. 030(K)(2) charges it proportionately, based on the ADU's square footage relative to the primary dwelling unit on the same lot, so a modest addition next to a large home pays less than the same-size ADU next to a small one. 030(J): an ADU isn't counted as a new residential use for calculating water or sewer connection fees or capacity charges unless it's built concurrently with a new primary dwelling, and an ADU located within the existing primary dwelling itself owes no new or separate utility connection fee at all.
030(J)(5) requires it to be proportionate to the burden the ADU adds to the water or sewer system, based on its size or number of plumbing fixtures, not a flat new-connection charge. 030(J)(6).
Violations & Fines
Charging a flat, size-blind impact fee on an ADU under 750 square feet runs counter to §19.442.030(K)(1)'s outright exemption; applicants can raise the discrepancy with the Community & Economic Development Department during plan check, since the section ties any fee for units 750 square feet and larger strictly to the ADU's proportion of the primary dwelling's square footage rather than a flat schedule.
Frequently Asked Questions
Does Riverside charge an impact fee for a small ADU?
How is the fee calculated for a larger Riverside ADU?
Do I owe a new water or sewer fee for my Riverside ADU?
Sources & Official References
Other rules in Riverside
California rules heatmap·Compare Riverside to another location·View the California accessory structures overview
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ADU Impact Fees in Nearby Cities
How other cities in Riverside County handle adu impact fees.