An ADU is a complete dwelling, which means it needs water in, waste out, power, and — if you want it — gas. None of that is decorative, none of it is optional, and almost all of it is buried. That combination is why utilities produce more mid-project surprises than any other category.
This guide describes what to investigate, not what your property requires. Utility requirements, capacity, connection methods, and fees are parcel- and provider-specific and change over time. Nobody — including us — can state your requirements without investigating your address. Confirm with your utility providers and the agency reviewing your project.
Why utilities belong in feasibility, not construction
Utility work is expensive to change late. Panel capacity affects equipment selection, which affects the mechanical plan. Sewer connection location affects where bathrooms and the kitchen can reasonably go. Trenching routes affect hardscape and landscaping that may need to be removed and restored. If those facts arrive after the design is fixed, either the design changes or the budget does.
Electrical
This is the most common issue on Los Angeles ADU projects, because much of the housing stock predates modern electrical demand.
What has to be established
- Existing service size and how much spare capacity remains.
- Panel condition, age, and whether it can accept additional circuits at all.
- The calculated load the ADU adds, based on actual planned equipment.
- Whether a panel or service upgrade is required.
- Whether the ADU is separately metered or served from existing service.
- Routing and trenching distance from the point of connection.
- Whether solar, battery, or EV charging is planned now or later.
All-electric ADUs avoid gas piping entirely and align well with current California energy requirements, but they add electrical load — which makes the capacity question more consequential, not less. The two decisions have to be made together.
Water
The questions are capacity and routing: is the existing water service adequate for an additional dwelling, where does the new line run, how far is the trench, and does the ADU get its own shutoff and, if applicable, its own meter? Fixture count and any tankless water heating equipment influence the sizing. Long runs across a finished backyard also mean hardscape removal and restoration, which is a construction cost rather than a plumbing one.
Sewer and waste
Waste is gravity-driven, so location and elevation matter more here than anywhere else in the project. What gets investigated:
- Where the existing private sewer lateral runs and how deep it sits.
- Its condition — older laterals are sometimes found to need repair or replacement.
- Whether adequate slope exists from the ADU to the connection point.
- Whether a new connection is needed instead of tying into the existing lateral.
- On septic systems, whether the existing system can accommodate an additional dwelling — a substantially larger analysis.
When gravity does not work, pumped solutions exist but add equipment, power, and long-term maintenance. Better to know before the floor plan is final.
Gas
Gas is increasingly optional. If you want it, the questions are whether the existing service and meter can support the added appliances, what new piping is required, and how it is routed to a detached structure. If you skip it, you are choosing an all-electric unit — heat pump heating and cooling, heat pump or electric water heating, and induction or electric cooking — which loops back to the electrical capacity question above.
How ADU type changes utility work
- Detached — longest runs, most trenching, most site restoration.
- Attached — shorter runs, but must coordinate with existing systems inside the house.
- Garage conversion — partial service may exist, but a light circuit is not service sized for a dwelling.
- Above-garage — vertical routing and drainage design add complexity.
- JADU — created within the existing dwelling, so the work is usually internal.
How utilities show up in the budget
Utility scope spans trenching length, hardscape demolition and restoration, panel or service upgrades, sewer lateral work, new meters where applicable, and provider connection fees. This is exactly why we treat early figures as preliminary planning ranges — see the 500 sq. ft. ADU cost guide and the regional cost guide. A detailed proposal with itemized allowances follows feasibility and design.
And in the schedule
Utility coordination involves third parties, which makes it one of the harder phases to compress. Identify it early and sequence it deliberately — how long it takes to build an ADU in Los Angeles shows where it lands in the overall calendar.
Where to verify
State-level ADU provisions, including how utility connection requirements are addressed, are documented in the California HCD ADU Handbook (updated March 2026) and HCD's ADU resource page. For City of Los Angeles projects, begin at the LADBS ADU hub. Utility-specific requirements and fees come from the providers serving your address.
Questions to ask before design is final
- What is my existing electrical service size, and what capacity is left?
- Does the planned equipment list require a panel or service upgrade?
- Where is the sewer lateral, how deep, and what condition is it in?
- Is there adequate gravity slope from the proposed ADU location?
- Is the water service adequate, and does the ADU need its own meter?
- Gas or all-electric — and what does that choice do to the electrical load?
- How far is the trenching, and what hardscape has to be removed and restored?
- What connection fees apply, per the current provider schedules?
Frequently asked questions
Does an ADU need its own separate utility meters?+
Not automatically. Whether service is shared or separately metered depends on the design, the utility provider, and the jurisdiction. It is a decision to confirm during feasibility and design rather than assume in either direction.
Will I need to upgrade my electrical panel?+
Possibly. Older homes frequently have panels with little spare capacity, and an additional dwelling adds load — especially in an all-electric unit with a heat pump, induction cooking, and an electric water heater. A load evaluation answers this; guessing does not.
How does the ADU connect to sewer?+
Typically by connecting into the existing private sewer lateral or by running a new connection, depending on the location, depth, slope, and condition of what exists. Where there is a septic system instead, the analysis is different and usually more involved. Both require investigation, not assumption.
Are utility connection fees a real budget item?+
Yes, where they apply. Fees and requirements are set by each utility provider and jurisdiction and change over time, so confirm current amounts with the providers for your address rather than relying on a published figure.
Is an all-electric ADU a good idea?+
It can simplify the project by avoiding gas piping entirely, and California energy requirements increasingly favor efficient electric equipment. The trade-off is electrical capacity: all-electric raises the load, which can make a panel upgrade more likely. Weigh both together, not separately.
Why do utilities delay projects so often?+
Because they involve third parties. Provider coordination, connection scheduling, and any required street or right-of-way work sit outside both your control and your contractor's, which is why they should be identified during feasibility rather than during construction.
Get the utility questions answered first.
Send us your address and we'll investigate service capacity, sewer routing, and connection paths before anyone draws a floor plan.