The short answer: Do ADUs need separate utility meters? In California, state law does not make a separate electric, water or gas meter mandatory for an ADU, and a city cannot require a separate utility connection for a conversion ADU or a JADU. For a new detached ADU, the picture is more mixed: the city may be able to require a connection, and your utility company may have its own rules that matter more than the city’s. Whether you should separate the meters is a different question, and it depends on whether you will rent the unit or sell it.
Last verified: October 5, 2026 ยท Written by the ADU Scope editorial team
Key fact: There are three different decision-makers: the state (which limits what a city can require), the city (which issues the permit), and the utility (which sets its own service rules). A “no” from one does not cancel a “yes” from another.
What State Law Says About Utility Connections
California’s HCD ADU Handbook (March 2026) addresses utilities mainly through connection fees and capacity charges. Under Government Code section 66311.5, subdivision (b), an ADU created from existing space and a JADU are not treated as a new residential use for calculating connection fees or capacity charges, unless they are built at the same time as a new single-family home. Subdivision (d) separately bars an agency from requiring a new or separate utility connection for those units. Under subdivision (e), when fees do apply to other ADUs, they must be proportional to the burden the ADU places on the system, based on its square footage or drainage fixture units compared with the main house.
The same handbook confirms that building an ADU does not by itself trigger fire sprinkler requirements for the existing house if sprinklers were not originally required (Gov. Code section 66314, subdivision (d)(12)).
The state rule against requiring separate connections for conversions and JADUs is also summarized in our overview of California’s rules.
| Unit type | Separate connection required by the city? | Connection and capacity charges |
|---|---|---|
| Conversion ADU (existing space) | No | Not treated as new residential use unless built with a new house |
| JADU | No | Not treated as new residential use unless built with a new house |
| New detached or additional ADU | May be allowed | Proportional to burden (square footage or drainage fixture units) |
Separate Utility Meters for Electric, Water, Sewer and Gas: Four Different Questions
People ask “do I need a separate meter?” as if there is one answer. There are really four, because each utility is a different provider with different rules.
Electric
This is the one that causes the most confusion. PG&E’s Electric Rule 18 states that JADUs are not considered separate residential units and do not need to be separately metered. For a new detached ADU, the requirement depends on the utility’s tariff and local rules; the City of Oakland, for example, requires a separate meter when an ADU has its own address. State law bars a city from requiring a separate utility connection only for conversion ADUs and JADUs, so a new detached ADU can still need its own meter. If you are in PG&E territory, or any investor-owned utility, ask the utility directly for its written requirements before you design the electrical service.
Water and sewer
Most ADUs share the main house’s water and sewer lines. The trade-off is that a shared line is cheaper to build, but a separate connection can make sense if you plan to rent or sell the unit later. A builder source puts trenching for new lines at roughly $8,000 to $30,000, with sewer the most expensive part. Treat that as a vendor estimate, not a market average.
Gas
Many new ADUs are designed as all-electric, which avoids a gas meter entirely. If your city or utility has electrification incentives or rules for new construction, confirm them with the planning department.
Tip: Request a “will-serve” or service-requirements letter from each utility early. It tells you whether the existing service can support the new load and whether a new meter or service upgrade is needed.
Separate Utility Meters, Submeter or Shared Panel?
For electricity, you generally have three ways to handle the ADU. A builder-sourced comparison gives these cost ranges, which you should treat as rough estimates and confirm with local quotes.
| Option | Estimated cost | Best for |
|---|---|---|
| Separate utility meter | $4,500 to $9,500 installed | Long-term tenants who pay the utility directly |
| Submeter | $400 to $1,200 | Tracking the ADU’s usage without a separate utility account |
| Shared panel | Little or none, but a panel upgrade may be needed | Family use |
How to choose
- Family member or caregiver: a shared panel is usually the cheapest.
- Long-term tenant: a separate meter avoids disputes over who pays what.
- Future sale or condo conversion: separate utilities make a separate sale easier, though they are not the only requirement.
A submeter is not a utility-recognized billing meter in every case, so rules on billing a tenant for submetered usage vary by state and utility. In California, Public Utilities Code section 739.5 requires a master-meter customer to bill tenants at the same rate the utility would charge them directly, with an itemized bill. Do not assume you can bill tenants from a submeter without checking.
Beyond Separate Utility Meters: Capacity, the Cost That Surprises Owners
Even if no separate meter is required, the existing electrical service may be too small. A typical house with a 100-amp panel can have trouble adding a second dwelling with a range, water heater and heating or cooling. The upgrade might be a bigger panel, a larger service line or work by the utility, and the last of these can add time and cost that no one planned for.
Sewer capacity is the water-side equivalent. In some areas, adding a unit triggers a review of whether the lateral can handle the load. Because the state limits fees to a proportional share, ask the sewer agency to explain the formula it is using.
Attention: Utility timelines can be longer than permit timelines. Start the utility conversation before the plans are final, not after the permit is approved.
Separate utility meters: what the utilities and Oakland say
The utility’s own tariff often decides the electric question, so read it. PG&E’s Electric Rule 18 provides that separate premises are not served through the same meter (a rule effective March 24, 2021) and that each residential dwelling unit is metered individually, with listed exceptions such as pre-existing submetering. A later change effective June 23, 2025 states that JADUs are not dwellings and need neither a separate meter nor their own address.
A joint information bulletin from Oakland and PG&E applies the rule to ADUs: an ADU with its own address gets a separate electric meter, citing Public Utilities Code section 780.5, and a separate gas meter is needed when it has vented gas appliances. The same bulletin says Oakland allows only one electrical service connection per parcel, so “separate meter” and “separate connection” are different things. We could not read the text of section 780.5 itself, so treat that citation as the bulletin’s.
San Diego Gas & Electric’s Rule 19 says each new single-family or multifamily dwelling unit is metered individually, in a version revised in 2015 that does not mention ADUs. We did not review Southern California Edison’s rules.
A bill that would have let owners choose to serve an ADU from the existing meter, AB 1661 (2024), failed and was filed in February 2024. No state law currently lets a new detached ADU skip the utility’s metering rules.
Separate utility meters and solar: Title 24 requirements
Solar can affect your electrical design before the meter question comes up. The California Energy Commission says a new detached ADU must have a solar photovoltaic system (Energy Code section 150.1(c)14). The array can be added to an existing system on the same lot, and it does not matter which meter it serves. Attached ADUs built as additions, conversions of existing space and JADUs are not required to add solar.
Some guides mention an exemption for attached ADUs under 800 sq ft. The Energy Commission pages we reviewed do not include an 800 sq ft threshold, and the 2022 page says no such exception exists, so do not rely on it. Ask your building department which energy compliance path applies to your unit.
Separate utility meters in Los Angeles and San Francisco
Los Angeles Department of Water and Power publishes a fact sheet on individual metering that applies to new multifamily buildings, and it caps the number of meters per property. We found no LADWP page that sets ADU-specific metering rules, so ask the utility for a written answer. In San Francisco, the SFPUC says that in most cases ADUs do not pay additional capacity charges, and it asks applicants to submit a fixture count form for water and sewer sizing.
What we could not confirm about separate utility meters
- The text of Public Utilities Code section 739.5 on submetering. We cannot say whether it applies to a specific ADU arrangement beyond the billing rule cited above.
- Any Southern California Edison rule specific to ADUs.
- Whether LADWP has an ADU-specific metering policy.
- The cost ranges quoted above come from a builder source, not a utility or government schedule.
Frequently Asked Questions
Can my city force me to install a separate meter for a garage conversion?
Not under California law, which bars requiring a separate utility connection for conversions and JADUs.
Does a new detached ADU need its own meter?
State law does not mandate it, but your utility may. Ask for its written requirements.
Do ADUs pay utility connection fees?
Conversions and JADUs are generally not charged as new residential uses unless built with a new house. Other ADUs pay fees proportional to their burden on the system.
Is a submeter enough for a tenant?
It lets you track usage, but billing rules vary, and a separate meter is cleaner for tenants.
Next Steps
- California ADU Laws 2026
- ADU Impact Fees: When You Pay Them and How to Avoid Them
- Can You Sell an ADU Separately? California AB 1033 Explained
- Unpermitted ADU in California: How to Legalize It Under AB 2533
General information, not legal advice. Local rules and utility tariffs vary and change; confirm with your planning department and utility.
Sources: HCD ADU Handbook, March 2026 ยท Maxable Space: Separate utilities for an ADU ยท PG&E Electric Rule 18 ยท SDG&E Rule 19 ยท California Energy Commission, 2025 Energy Code support ยท SFPUC capacity charges