Published: 1 Nov 2026 · Last verified: 1 Nov 2026 · Next review: Jan 2027 Utility figures are re-checked quarterly. Changes are logged in Corrections.
Ask a contractor what utilities cost on an ADU and you’ll usually get a shrug inside the bid. Ask thirteen California cities and you get everything from $0 to $7,751 — for the same 800 sq ft box. Sewer, water, and power are the least itemized lines in ADU construction, and sewer is the most volatile of the three.
This post maps the real numbers from our published series: what each utility actually costs, which cities charge nothing, and where the traps are. Figures are compiled from the city and district fee schedules in our fee index — confirm your meter size and district charges with your utility before budgeting.
Sewer: the $0-to-$7,000 spread
Sewer capacity charges are set by sewer districts, which often aren’t the city — and ADU policies differ district by district. Our series data:
| City | Sewer charge (800 sq ft ADU) | Basis |
|---|---|---|
| Torrance | $0 | No ADU sewer capacity charge |
| Oakland | $0 | No ADU sewer charge |
| Sacramento | $0 | $0 sewer for ADUs |
| San Francisco | $0 | Minimal/none |
| Long Beach | ~$209 | Nominal |
| Burbank | $908 | With a 750 sq ft cliff — first in series |
| Anaheim | $1,368–$1,710* | OC San $1.71/sq ft |
| Fullerton | ~$1,710* | Per-sq-ft rate |
| Garden Grove | ~$1,710* | Per-sq-ft rate |
| Campbell | Up to $6,727 + $1,024 capacity | West Valley Sanitation: $567.68/drainage fixture unit (cap $6,727) + $86.42/fixture unit treatment capacity (cap $1,024) |
Three patterns emerge:
- The $0 cities. Torrance, Oakland, Sacramento, and San Francisco charge ADUs nothing for sewer. This is usually a deliberate policy choice — the ADU rides on the existing lateral, and the district absorbs the marginal load.
- The per-square-foot cities. Anaheim, Fullerton, and Garden Grove (all Orange County, all on OC San) charge around $1.71/sq ft — roughly $1,368–$1,710 on 800 sq ft. Predictable, middle of the road.
- The fixture-unit cities. Campbell’s West Valley Sanitation District charges per drainage fixture unit — $567.68 per DFU up to $6,727, plus a treatment capacity charge. A full bathroom + kitchen ADU can stack fixture units fast. This is the highest sewer exposure in our data.
Burbank’s sewer cliff deserves its own mention: the first 750-sq-ft-style cliff we’ve seen applied to sewer specifically, not just impact fees. Size the ADU at 749 and the sewer charge vanishes; at 750, it’s $908.
Water: mostly actual cost
Water is simpler but murkier. Most cities and water districts charge ADUs at actual installation cost — trenching, pipe, meter upsizing — rather than a published capacity fee. That means:
- If your existing water service is adequate, the water cost can be near $0 beyond the plumber’s rough-in.
- If the district requires a larger meter or a new lateral, you’re paying the crew’s invoice — $2,000–$8,000+ depending on distance and street work.
- Fire sprinklers change everything. If the ADU requires sprinklers (common on detached units), the water district may require a larger service line, and the cost jumps.
State law (Gov. Code §66324) bars cities from treating ADUs as new residential uses for utility purposes in many configurations — which caps what districts can demand. But “actual cost” is still actual cost, and nobody publishes it in advance.
Power: the panel question
Electrical is the most predictable of the three, and the least jurisdictional:
- Panel upgrade: If the main house panel can’t carry the ADU load, a 200-amp upgrade runs $2,000–$5,000 installed. This is the most common power cost on ADU projects.
- Separate meter: Optional in most cases; costs $1,000–$3,000 if you want one for submetering rental income.
- Underground service: If the utility requires undergrounding, trenching costs apply — same crew math as water.
None of our thirteen cities levies a distinct “electric capacity charge” on ADUs. Power costs are contractor costs, not fee-schedule costs — which is exactly why they disappear from quotes.
The SB 1196 footnote
There’s a fourth utility bill coming: time. Some ADU owners currently wait 9–12 months after construction for the utility to energize the unit. SB 1196, signed in 2026, requires California utilities to set a firm connection-application deadline starting in 2027. It doesn’t change the dollar cost — it changes the carrying cost of a finished, unrentable ADU. Price the wait into your pro forma, not just the wire.
What to ask before you budget
- Which sewer district serves the parcel? (Often not the city.) Ask for their ADU capacity-charge policy in writing.
- Is there a sewer cliff? Burbank proved the concept exists — ask whether 749 vs. 750 sq ft changes the number.
- Will the water district require a meter upsize? Get the trigger threshold (usually tied to fixture count or sprinklers).
- Can the existing electrical panel carry the ADU? Have the electrician answer this during bidding, not after rough-in.
- Get the “actual cost” items estimated anyway. “Actual cost” isn’t a number until someone trenches — make the contractor price the trench.
The bottom line
Budget $0–$8,000 for sewer/water/power combined on an 800 sq ft ADU, and verify which end of that range your parcel sits on before you sign a bid. The cities that charge $0 aren’t being generous — they’ve decided the marginal load isn’t worth metering. The districts that charge per fixture unit have decided the opposite. Neither answer appears in a contractor’s quote, which is why this post exists.