ADU Utilities: Separate Meters, Septic & Impact Fees

Utilities are the least glamorous part of an ADU project and one of the most consequential for the budget. How you connect water, sewer, and power — and what your county charges for the privilege — can swing a project by tens of thousands of dollars. Here is how we plan ADU utility connections in South Florida, and the questions to answer before your drawings are finalized.

Electric: Subpanel or Separate Meter?

Most ADUs are served one of two ways:

• Subpanel from the main house. The ADU gets its own panel fed from your existing service. Simplest and cheapest — but the main service must have capacity. Many older South Florida homes with 100–150 amp service need a service upgrade to add a second dwelling with its own HVAC, kitchen, and laundry.
• Separate meter. The utility sets a second meter, and the ADU becomes its own electrical customer. This costs more up front but is the cleanest arrangement for a rental ADU — tenants pay their own bill, and you never argue over air conditioning in August.

Your electric utility's requirements and your city's rules both apply; some jurisdictions restrict separate meters on accessory units, others encourage them. We resolve this during design on every ADU construction project.

Water and Sewer: Tapping In

For water, the common options are branching from the house's service line or setting a dedicated meter from the main. Branching is cheaper; a separate meter simplifies rentals and can matter for irrigation billing. For sanitary sewer, gravity is destiny: if the ADU's drains can fall to the existing lateral or the street main, the connection is straightforward trenching. If grades do not cooperate — common on flat South Florida lots with elevated finished floors — a small sewage lift station adds cost and a maintenance item. Long trench runs across a landscaped yard also carry restoration costs people forget to budget.

On Septic? Capacity Is the Whole Question

If your property uses a septic system, the ADU's bedrooms count. Septic systems in Florida are permitted by bedroom count and estimated flow; adding a dwelling usually requires a septic system evaluation and often a modification — a larger or additional drainfield, or in some cases a new tank. Lot size, setbacks from wells and water bodies, and the seasonal high water table all constrain where a drainfield can go. In areas transitioning to municipal sewer, connecting to sewer as part of the project can be the smarter long-term move. Either way: resolve septic feasibility before you fall in love with a floor plan.

Impact Fees and Connection Charges: The Wild Card

When you add a dwelling unit, counties and utilities may charge one-time fees intended to fund infrastructure capacity — water and sewer connection charges, and impact fees for roads, schools, and parks depending on the jurisdiction. Typical ranges in South Florida run from a couple of thousand dollars to well into five figures, and several Florida jurisdictions have reduced or waived impact fees for accessory dwelling units to encourage them. Because the spread is so wide, we pin down the actual fee schedule for your address during feasibility — it is one of the first numbers in our budget worksheets, alongside the items covered in our FAQ.

HVAC, Gas, and the Florida Envelope

A few Florida-specific notes that affect utility planning:

1. Cooling is its own system. The ADU gets dedicated HVAC — usually a mini-split or compact ducted system — never an extension of the main house's ductwork.
2. Humidity control matters as much as temperature. Proper sizing beats oversizing; an oversized system short-cycles and leaves the unit clammy.
3. Gas. If the main house has gas, extending it for a tankless water heater or range is often worthwhile; otherwise, all-electric with a heat-pump water heater is efficient and simple.
4. Storm resilience. A generator-ready transfer switch or interlock installed during construction costs little and is invaluable after a hurricane.

Sequence It Right and It Is Routine

None of this is exotic — it is coordination. Utility routing belongs on the site plan, capacity questions belong in feasibility, and fees belong in the budget before contracts are signed. That sequencing is what a design-build firm does by default, whether the project is an ADU, a home addition, or a full custom home.

Work With Xpert Construction Group

Xpert Construction Group plans and builds every ADU utility connection — meters, septic, HVAC, and fees — as part of one integrated design-build scope. We are a Florida licensed and insured general contractor (CRC 1335930). Contact us for a free consultation and a utility-realistic budget for your lot.