Utility hookups are one of the least visible parts of an ADU build, and one of the biggest hidden cost swings between projects. Here's how each system typically works.
Most Utah ADUs tie into the primary home's existing water and sewer lines rather than requiring a brand-new connection to the city main, which keeps costs down substantially compared to a standalone lot. Whether your city requires a separate water meter for the ADU (common if you plan to rent it out and want to bill tenants directly for usage) versus sharing the primary home's meter is a city-specific and sometimes lot-specific question we confirm during your site visit.
Most ADUs run off a new sub-panel fed from the primary home's existing electrical service, provided that service has enough remaining capacity. If your existing panel is older or already near capacity, a service upgrade may be required before the ADU's sub-panel can be added, which is an added cost worth knowing about early rather than discovering mid-construction. Some homeowners planning to rent the unit long-term opt for a fully separate meter so utility billing is cleanly split between units; this typically costs more upfront but simplifies tenant billing later.
If your ADU includes gas appliances (a furnace, water heater, or range), the gas line typically extends from the existing service line, similar to the electrical approach. Detached ADUs generally require a trenched line run underground from the main house or meter to the new structure, which adds both cost and, in colder months, a dependency on ground conditions and frost depth for trenching.
The single biggest cost factor across all three utilities is distance: how far the ADU sits from the existing hookup points on your property. A garage conversion sitting right next to the house is the cheapest scenario since utility runs are short. A detached ADU at the back of a deep lot means longer trenching for water, sewer, gas, and electrical conduit, which adds real cost regardless of how simple the rest of the build is.
Existing capacity is the second factor. An older home with a 100-amp electrical panel already near its load limit, or a sewer lateral that's aging or undersized, may need upgrades before the ADU can even be added, and those upgrades benefit the main house too, not just the new unit.
Utility planning happens during your free site visit and design phase, before you're committed to a number. We coordinate directly with utility providers and the city on service capacity, trenching requirements, and meter setups, so utility costs show up as a clear line item in your estimate rather than a surprise change order mid-build. For a full picture of how utility costs fit into overall project budgets, see our ADU cost breakdown.