Mesa gives ADU owners more choice on utilities than any other Valley city: the ordinance says a casita may have its own meters or submeters for water, sewer, and electric, with permits. That flexibility is real, but one line in the City's fee schedule makes the decision for most people. Here is how each connection works on a Mesa lot, what we verify, and what it costs.
The short version
In Mesa, your ADU ties into the water and sewer service your home already has, and gets its own electric meter from SRP or, in the downtown service area, City of Mesa Electric. A separate City water meter is allowed but rarely worth it, because a new or upsized Mesa meter triggers the City's water and wastewater capacity fee.
Distance from your home's lines to the ADU is still the biggest driver of utility cost. We route trenches as short as the lot allows, and we confirm your electric provider by address before anything is drawn.
What Mesa's ordinance actually says
Mesa's zoning ordinance requires three things of every ADU: it must be provided with water, sewer, and electric; it must be served by the same utility provider as the primary residence; and it can't sit on a public utility easement without written consent from the utilities that use it (City of Mesa ADU page). The City's ADU FAQ adds that an ADU "may have separate meters or sub-meters for water, sewer, and electric utilities, but permits are required." Mesa's first ADU ordinance in 2024 required the same meters as the house; the current version dropped that, so the choice is now yours.
Sewer: one line, one account
Your ADU connects to your home's existing sewer line, not to a new city tap. Mesa's utility terms require each parcel to be served from its own connection to the public main, and the parcel is the unit, not the building, so the casita sharing the house's lateral is the normal arrangement. Sewer in Mesa is billed off the water meter, so there is no separate sewer account unless there's a separate water meter.
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 pipe is replaced as a change order.
- Easements. Mesa doesn't allow a detached accessory structure to encroach on any recorded easement, so we pull the plat before we place the unit.
- Septic lots. If your home is on septic, Maricopa County Environmental Services reviews the system for the added load before the City will issue a permit.
Water: share the meter, skip the capacity fee
Your ADU tees off your home's water line after the existing City meter, with its own shutoff valve. Mesa will set a separate meter for an ADU if you ask, but since January 2026 a new or upsized Mesa water meter triggers the City's water and wastewater capacity fee, a one-time charge that runs into several thousand dollars for even a 3/4-inch meter, on top of the meter installation fee. That is why the shared line is our standard, and why we run the fixture count early: if your existing meter is adequate for the house plus the ADU, no upsize and no capacity fee.
- Meter size check. We calculate the combined fixture load of your home plus the ADU. If your current meter can't carry it, an upsize is required, and the capacity fee applies to the difference in size.
- 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 without a second City account. Arizona's tenant-billing rules are in our separate meter vs. submeter guide.
Electric: SRP or City of Mesa, its own meter
Most of Mesa is SRP territory. Roughly five and a half square miles around downtown are served by City of Mesa Electric instead, and the ordinance requires the ADU to use the same provider as the house, so there's no choosing between them. Either way, the ADU gets its own meter, its own bill, and adds no load to your home's panel.
- SRP areas. SRP supplies one service per building, and a detached casita is its own building. SOKO applies, SRP sets the connection point, we trench and install conduit to their design, and SRP pulls wire and sets the meter.
- City of Mesa Electric areas. The City quotes connection and metering facilities per project. We request the quote as part of design so it lands in your proposal, not as a surprise.
- Address. A separate meter needs its own address. Mesa Development Services assigns it at permit, and SOKO handles the request.
- Lead time. Meter scheduling is set by the utility, not SOKO.
Option: power from your home's panel
Mesa allows the ADU to share the house's electric service, so we can instead feed it from your home's panel on one bill when a load calculation shows 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 Mesa
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 or Mesa Electric 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 or Mesa Electric, City of Mesa, 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 |
| Separate City water meter for the ADU | City meter + capacity fees at cost + $1,500 | Optional; allowed by Mesa, but the capacity fee makes it rare |
| 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 fees at cost + $1,500 | Only if the fixture calculation exceeds your current meter; capacity fee applies to the size difference |
| 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.
- Your water meter. An adequate existing meter keeps you clear of the capacity fee. An undersized one is the biggest fee swing on a Mesa project.
- Your electric provider. SRP connections follow a published process; City of Mesa Electric connections are quoted per project.
- Soil and existing conditions. Caliche, old clay sewer pipe, and shallow laterals in older central Mesa neighborhoods add scope.
What this pricing assumes
- Pricing applies to City of Mesa projects. For other cities see our posts for Phoenix, Scottsdale, 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 gas service (Mesa's municipal gas or Southwest Gas), relocation of existing utilities, landscape and hardscape restoration beyond the trench, and repairs to existing home systems.
- Requirements reflect Mesa Zoning Ordinance Section 11-31-3 and City utility policies as of September 2026 and may change.
We run this for you
In Mesa the utility decision is mostly a fee decision, and we make it with real numbers: your meter size, your fixture count, and your electric provider, confirmed before the plans are drawn. Building a casita in Mesa? Check your property or call 480-660-3133.
Sources: Mesa Zoning Ordinance §11-31-3 (Accessory Dwelling Units); City of Mesa ADU page and FAQ; City of Mesa Utility Rate Book and Water/Wastewater Capacity Fee page; SRP Electric Service Specifications; Maricopa County Minor Plan Review instructions. City policies, utility requirements, and fees change; verify current requirements with the City of Mesa 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.
