01
How Reno, Sparks and Washoe County each review an ADU
The review path the utility referrals sit inside, from feasibility note to final inspection.
How water, sewer, power and gas reach an ADU in Reno, Sparks and Washoe County
Water, sewer, power and gas are each arranged with the provider that serves that line, septic is permitted by Northern Nevada Public Health, and whether an ADU in Reno, Sparks or Washoe County may share the main house’s service depends on the provider and the place. Sparks Municipal Code 20.03.003 requires shared water, electric and gas meters, Truckee Meadows Water Authority (TMWA) Rule 6 says a suitable meter shall be installed at each building, and on a septic lot Northern Nevada Public Health requires a septic system for each dwelling. This page names who decides each line, as read on 22 October 2026, and says which fees it will not print.
- Published
- 23 October 2026
- Subject
- Water, sewer or septic, power and gas for an ADU
- What we will not do
- Print a connection fee or promise a separate meter
- Faster than reading
- (775) 200-0648, Monday to Friday, 9:00 AM to 4:00 PM
01Four lines
Each utility line to an ADU is its own conversation, with the provider that serves that line.
Washoe County’s ADU Hub tells owners to arrange utility connections and fees directly with each provider, and says the water and sewer connection fee is typically the largest of them. In unincorporated Washoe County, permits for power, water and sewer go through the county Building Department working with the local purveyors, the utilities that serve the area.
Water and sewer can come from different agencies on one parcel: when the county’s water utility and the South Truckee Meadows General Improvement District were consolidated into TMWA on 31 December 2014, TMWA told those customers their sewer provider would not change. The county’s Washoe Regional Mapping System shows a parcel’s municipal water and sewer service.
Water, sewer or septic is also one of the six things the building department asks for in how Reno, Sparks and Washoe County each review an ADU; this page is the detail behind that line.
02Water
TMWA sends a property with an ADU to its Commercial Service application, and in Sun Valley a detached unit needs its own connection to the water main.
TMWA’s New Business application outline sends a property with an accessory dwelling unit to its Commercial Service application, which covers residential projects with more than one dwelling unit on a single property.
Under TMWA Rule 7, new or modified service needs an application and, if TMWA decides water resources are needed for the added demand, a will-serve commitment letter (TMWA’s written commitment to serve it), which comes from signing qualifying water rights (the legal right to use a set amount of water) over to TMWA or from buying the letter. Rule 6, Section F.1 lets TMWA require a separate service and meter for each building where it needs one for operation, maintenance or billing, and the same paragraph says a suitable meter shall be installed at each building; the section never mentions an ADU. The applicant installs the facilities at its own expense.
In the Sun Valley General Improvement District, the local district that supplies water and sewer in Sun Valley, a detached ADU needs its own service line, its own tap (a separate connection into the water main), its own meter and its own dedicated water rights, while an attached unit extends the main house’s line; either way the owner needs the district’s will-serve letter.
On a private well, an ADU’s household water counts as domestic use only where a local ordinance provides for the unit (NRS 534.013); the conditions are in the last question below.
03Sewer and septic
Sewer comes down to a connection fee paid around the permit, and septic to whether the lot can hold a second system.
Reno Municipal Code 12.16.290 charges the sewer connection fee at a flat rate for each residential unit, rising each 1 July with the consumer price index. Under 12.16.280 it is paid before the building permit issues, or for a new connection may be deferred until before the certificate of occupancy, the sign-off to live in the building; a connection made without a permit and paid fees is charged twice the fee (12.16.280(e)).
Sparks Municipal Code 13.24.020 also charges the fee per residential unit, adjusted each January from 2027 by the Engineering News Record Construction Cost Index, payable when the building permit issues or deferred until before the certificate of occupancy or for 12 months, whichever comes first (13.24.010).
Washoe County’s sewer utility serves unincorporated Washoe County and parts of Reno and Sparks, and its Ordinance 1713 collects connection charges before a final map (the recorded map that creates new lots) is approved, before the sewer connection permit, or before the certificate of occupancy. In Sun Valley, the general improvement district requires a detached ADU to have its own sewer line and tap unless it allows an extension of the house’s line case by case.
On septic, Northern Nevada Public Health (NNPH) regulates residential systems across Washoe County, and its handout H-482 says each dwelling must have its own septic system and designated repair area, the ground held back for a replacement field, with at least one acre per system. The process starts with a test trench inspection of the soil, a new system is permitted with the building permit it serves, staff visit the site on every application, and NNPH lists a 14-day plan review for new systems.
The planning department decides whether a building is an ADU or guest quarters, which have no kitchen, and NNPH follows that call; for guest quarters it checks that the existing system is sized for the bedrooms in every building. On a septic lot, then, whether a kitchen makes the building an ADU also decides which septic review it gets.
04Power and gas
NV Energy sets no meter until the inspector signs off and the address matches.
NV Energy will not set an electric meter without the city or county inspector’s approval, and the address it is given must match the building department’s exactly, marked permanently on the structure first. Its Residential Project Information Sheet adds that no meter is set without an approved address from the county building department.
New service starts with notice of intent to build and a formal application, which for a home is that Residential Project Information Sheet; the sheet also asks whether the project is a panel upgrade (the panel is the breaker box the house’s power runs through).
NV Energy offers gas service only in the Truckee Meadows, the Reno and Sparks area. Before it sets a gas meter, the interior piping must pass a manometer test (a pressure test of the gas lines), at least one appliance must be installed, and the building department must have approved.
In Sparks, Municipal Code 20.03.003(C)(6) and (C)(7), as codified through Ordinance 2676 and read 22 October 2026, say an ADU shall not obtain a separate address and shall use the main house’s water, electric and gas meters. On our jobs, where each line comes from, whether the electric panel has capacity for a second dwelling, and whether separate metering is wanted are all settled in the site, utilities and services step of how we build an ADU, before design starts.
05The refusal
We will not print a connection fee, or promise that your ADU gets its own meter.
This page prints no sewer, storm drain, water rights, will-serve, septic or permit fee, and does not promise that your ADU gets its own water meter, electric service or address; where a published rule speaks to it, as the Sparks code and the Sun Valley district tariff do, we quote the rule and the date we read it.
The Reno and Sparks codes charge per residential unit without saying whether an ADU is one. Reno’s current fee schedule is published as a scanned image, Washoe County’s base charge rises every 1 January by the same construction cost index, and TMWA prices a will-serve letter by formula. Every price this site prints comes from our cost calculator, which does not price an ADU.
No TMWA rule we read says when an ADU gets its own meter: Rule 6 says a suitable meter shall be installed at each building and lets TMWA require a separate service, and how that applies to your unit is TMWA’s answer to give in writing. We found no NV Energy rule on a separate electric service for a detached unit. The online Sparks code, current through Ordinance 2676 of 27 July 2026, still shows the shared-meter rule as adopted in 2015, and an amendment adopted after that date would not show there yet; the 2025 state ADU law, AB 396 (NRS 278.257), says nothing about meters or addresses.
Washoe County GIS, the county’s mapping and addressing office, is the contact for new residential and utility addresses in unincorporated Washoe County and inside Reno city limits; its page does not say whether an ADU gets its own, and no page we read says who addresses a building inside Sparks.
Each answer is given by the provider for one parcel, and a number from the wrong year or category is worse than none. Ask each provider in writing before the site plan, the drawing that places the unit and its utility runs on the lot, is fixed.
06Questions
Three questions about getting utilities to an ADU.
Sparks Municipal Code 20.03.003(C)(7) says an ADU shall use the same water, electric and gas meters as the main house. Reno’s ADU guide (revised 10/13/25) sets no meter rule and lists TMWA as the agency to ask. Where TMWA serves the parcel, its Rule 6, Section F.1 lets it require a separate service and meter for each building, says a suitable meter shall be installed at each building, and lets owners of a property with more than one occupancy unit ask for a meter per unit, granted where feasible for TMWA’s operating convenience. That section never mentions an ADU, and nothing we read reconciles it with the Sparks code, so ask TMWA, and in Sparks the city too, in writing. In the Sun Valley General Improvement District, a detached ADU must have its own tap, meter and water rights. Read 22 October 2026.
Only in part. Northern Nevada Public Health (NNPH) requires each dwelling to have its own septic tank and designated repair area, with at least one acre of property per septic system (handout H-482, Rev. 02/2026). Two dwellings may share one leach field, the buried bed that disperses treated wastewater, if it is sized for their combined tank volume or total bedrooms. Both systems and repair areas must meet the setbacks, the minimum distances each system has to keep, in Section 040.100, Table 1 of the Sewage, Wastewater and Sanitation Regulations, and the handout warns that a parcel with enough acreage often still lacks room for every setback, and then the project will not be approved.
It can, with conditions. Nevada counts an ADU’s household water as domestic use where a local ordinance provides for the unit (NRS 534.013). The well owner must get approval from the local governing body or planning commission, meter the well’s total withdrawal, and keep it at or under 2 acre-feet a year (NRS 534.180(4)); an acre-foot is the water that would cover one acre a foot deep. In unincorporated Washoe County, a detached ADU on a domestic well must also have a water meter (Washoe County Development Code 110.306.25(j)).
07Keep going
Three pages for what comes after the utility question.
02
The kitchen is what makes a converted garage an ADU in Reno and Washoe County
The classification that decides whether septic needs a second system or a bedroom check.
03
What Reno, Sparks and Washoe County allow when you rent out an ADU
What state law now protects when the unit is rented as housing, and why shared meters matter more once it is.
08Start a conversation
Give us the parcel number, and we will tell you which provider answers for each line.
No fee guesses and no meter promises. We will name who serves water, sewer or septic, power and gas on your parcel, and what each one asks for, so the site plan starts from their answers.
Fastest way to reach us
(775) 200-0648
Monday to Friday, 9:00 AM to 4:00 PM. A person answers. The form goes to the same place, one business day behind the phone.
Question received.
We will call you back within one business day with the answer for your address. If you would rather not wait, call (775) 200-0648 now, Monday to Friday, 9:00 AM to 4:00 PM.