Every casita needs three things before anyone can live in it: somewhere for the water to come from, somewhere for it to go, and power. In the City of Phoenix, the rules for all three are unusually clear, and they happen to be the money-saving version. Here is exactly how your ADU gets connected, what we verify on your lot, and what each piece costs.
The short version
In Phoenix, your ADU shares the sewer and water service your home already has, and gets its own electric meter. That keeps connection costs down and gives the unit its own power bill from day one.
We keep every trench run as short as the site allows. Distance from your home's lines to the ADU is the single biggest driver of utility cost, which is why utility routing is part of where we place the unit, not an afterthought.
Sewer: one line, one account
Your ADU connects to your home's existing sewer line, not to a new city tap. Phoenix Water Services policy requires ADUs to share the home's sewer service, and the shared connection is still billed as one single-family account. That is spelled out in the City's ADU water and wastewater policy. A separate tap is only entertained through a technical appeal when sharing genuinely isn't feasible, and on a normal residential lot it almost always is.
What we verify at the site visit:
- Grade. Sewer flows by gravity. If the ADU sits lower than your home's line, a small ejector pump may be needed.
- Pipe size and condition. We confirm a 4-inch line. Older homes may get a camera inspection first; damaged clay pipe is replaced as a change order.
- Easements. The ADU can't be built over a public utility easement without the utility's written consent.
- Septic lots. If your home is on septic, Maricopa County must confirm the tank can take the extra flow.
Water: tee off after your meter
Your ADU tees off your home's water line after the existing city meter, with its own shutoff valve. Phoenix allows one water meter connection per lot for an ADU project, so a second city meter from the street is not the standard path (see the City of Phoenix ADU process).
- Meter size check. We calculate the combined fixture load of your home plus the ADU. If your current meter is too small, the City requires an upsize, and new taps must be at least 1 inch (City meter sizing guideline).
- Optional private submeter. Planning to rent the ADU? A submeter on the ADU's line lets you track its water use and bill a tenant. The City doesn't read it; you do. It's an add-on, installed during plumbing rough-in. Arizona's rules for billing a tenant off a submeter are covered in our separate meter vs. submeter guide.
Electric: its own meter, its own bill
Your ADU gets its own electric meter from SRP or APS, whichever serves your home. That means a separate power bill and no added load on your home's panel.
Standard: new, separate meter
- SOKO applies to SRP or APS, and the utility sets the connection point.
- SOKO digs the trench and installs conduit to the utility's design; the utility pulls the wire and sets the meter (SRP electric service specifications).
- A separate meter needs its own address. SOKO requests it from City of Phoenix Addressing Services.
- Plan on added utility lead time. Scheduling is set by SRP or APS, not SOKO.
Option: power from your home's panel
We can instead feed the ADU from your home's electrical panel, with one shared bill. This works when a load calculation shows your panel has room, usually a 200-amp service. It's often a fit for family or guest use, and if you have rooftop solar it's usually the better economics. If your panel is too small, a new ADU meter is usually better value than upgrading your home's service.
What it costs in Phoenix
Utility connections are priced per linear foot of trench plus fixed connection items. Your proposal shows the measured run lengths for your site.
Standard connections
| Item | Price | Includes |
|---|---|---|
| Sewer line, ADU to home's line | $65 / LF | Trench, 4" pipe, bedding, backfill, compaction |
| Sewer tie-in + cleanout | $1,200 each | Connection to your home's line, required cleanout |
| Water line, in shared sewer trench | $20 / LF | Pipe and fittings in the same trench as sewer |
| Water line, separate trench | $35 / LF | Trench, pipe, fittings, backfill |
| Water tie-in + ADU shutoff valve | $750 | Tee after your city meter, dedicated ADU shutoff |
| Electric trench + conduit | $40 / LF | Trench and conduit per SRP/APS design |
| New meter service + ADU panel | $6,000 | Meter base, main disconnect, ADU panel, grounding |
| Second address (required for new meter) | $350 | SOKO request and coordination with the City |
| Utility and City fees | At cost | SRP/APS, City of Phoenix, passed through with no markup |
Add-ons and site conditions
| Item | Price | When it applies |
|---|---|---|
| Water submeter on ADU line | $750 | Optional, for rental billing |
| Power from home's panel instead of new meter | $3,500 + $40 / LF | Optional, if load calc allows; replaces the $6,000 meter service and $350 address |
| Sewer camera inspection | $350 | Older homes or unknown pipe condition |
| Sewer pump (ejector) | $4,500 allowance | Only if the ADU sits too low for gravity flow |
| Water meter upsize | City fee at cost + $1,500 | Only if the fixture calculation exceeds your current meter |
| Caliche, rock, or hardscape removal | Cost + 25% | Found during excavation |
Example: a 40-foot run with shared sewer and water trench, a separate 40-foot electric trench, and a new meter comes to about $13,300 before City and utility fees.
What moves the number
- Distance. Every foot between your home's lines and the ADU is priced. We place the ADU and route trenches to keep runs short.
- Soil. Caliche and rock are common in Phoenix and slow excavation.
- Existing conditions. Old or damaged sewer pipe, a shallow sewer line, or an undersized water meter add scope.
- Utility requirements. SRP or APS sets the meter location and service route, which can lengthen the electric trench.
What this pricing assumes
- Pricing applies to City of Phoenix projects. Other Valley cities handle water and sewer differently; see our city-by-city posts for Scottsdale, Mesa, Tempe, Chandler, Gilbert, and unincorporated Maricopa County.
- Run lengths are measured at the site visit and confirmed on the permit site plan.
- Utility and City fees are billed at cost, as invoiced.
- Excludes relocation of existing utilities, gas service, landscape and hardscape restoration beyond the trench, and repairs to existing home systems.
- Requirements reflect published City of Phoenix and utility policies as of September 2026 and may change.
We run this for you
Utility routing is decided on the first site visit, not discovered at plan review. We measure the runs, confirm your sewer and meter, apply to SRP or APS, and pull the second address, so the connection line in your proposal is a real number instead of an allowance. Building an ADU in Phoenix? Check your property or call 480-660-3133.
Sources: City of Phoenix Water and Wastewater Service Policies for ADUs; City of Phoenix ADU Residential Process; City of Phoenix Water Meter Sizing Guideline; SRP Electric Service Specifications. City policies, utility requirements, and fees change; verify current requirements with the City of Phoenix and your utility before making design decisions. Pricing shown is SOKO's standard connection pricing as of September 2026 and is confirmed in your written proposal.
