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Utility connection refused for an ADU: what to check

By the HyreADU research desk. Last checked .

The short answer

A utility connection refused for an ADU usually means the sewer line, water service or electrical service cannot serve a second unit as designed.

In California, an ADU is not treated as a new residential use for connection fees unless built with a new house, and some ADUs need no separate connection.

Ask the utility for its reason in writing and what upgrade would satisfy it.

Why it happens

  • Sewer: the existing lateral is too small, damaged, or the main has no capacity.
  • Water: the meter or service line is too small for two units.
  • Electrical: the panel or the utility transformer cannot carry the added load.
  • Septic: the system cannot take the added flow. See septic capacity.

What California law says

Under Gov. Code § 66311.5, an ADU is not a new residential use for calculating connection fees or capacity charges unless it is built with a new single-family home, and the law also limits when some ADUs, such as certain conversions within existing space, can be required to install a new or separate connection.

Ask the utility which rule it applied. Where a new connection is required, the charge must be proportional to the ADU’s burden.

Connection and capacity charges are not impact fees, so the 750 sq ft impact-fee rule does not remove them. We give no legal advice on disputes.

What to do this week

  1. Get the refusal or condition in writing, with the capacity figure it relies on.
  2. Ask what upgrade would allow the connection: a larger lateral, a new meter, a panel upgrade.
  3. Have a plumber camera the sewer lateral if its condition is the issue.
  4. Ask an electrician for a load calculation.
  5. Ask your designer whether the design can reduce the load, such as with efficient equipment.

Who fixes it, and what it costs

A plumber, electrician or civil engineer designs the fix; the utility approves it. Costs are the upgrade work and any proportional charge, named as lines in your budget, never guessed here. See ADU sewer lateral, electrical panel upgrade and our utility connection research.

A mistake to avoid

The mistake to avoid is redesigning the whole ADU before you know what the utility needs. Often the fix is a single upgrade, such as a larger lateral or a new meter, and the design can stay as it is. Get the requirement in writing first.

What to do next: check your lot with the ADU feasibility checker, read the questions to ask an ADU builder, then tell us about your project. Matching is not live yet, so we reply with information, not a quote.

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Questions

Can a utility refuse to connect an ADU?

It can set conditions when capacity is short. It must follow state rules on ADU fees and charges.

Does my ADU need its own meter?

Not always. Some utilities require one; some ADUs can share.

Is a panel upgrade a utility issue?

The panel is yours; the service drop and transformer are the utility’s.

Are connection fees waived for small ADUs?

Impact fees are; connection and capacity charges are a separate rule.

Sources

HyreADU is a publisher. It does not design, permit or build ADUs, has no partner builders, and gives no legal, tax, lending or engineering advice.

Rules vary by state and city; California rules are labeled as such. Spotted an error? Tell us through our corrections page. Licensed professionals can also contribute as named sources.