Septic System Permit (Conventional and Alternative) in Unincorporated Navajo County, Arizona

Unincorporated Navajo County requires a septic system permit (conventional and alternative) for: Conventional system: Construction Permit Application, ADEQ General Permit 4.02 Notice of Intent to Discharge, GP 4.02 Checklist, GP 4.02 Calculation Worksheet, ADEQ Site Investigation Report Form, Bill of Materials, Trench Detail, and a copy of the Onsite Findings Report (NCERA Form 310); Soil suitability for a conventional system requires a percolation rate of 10-120 minutes-per-inch (MPI), or a Soil Absorption Rating (SAR) of .2 or higher, with a 5-foot minimum separation from groundwater or an impermeable confining layer; If percolation is slower than 120 MPI or SAR is below .2, an alternative on-site disposal system may be permitted through ADEQ, and Navajo County does permit several alternative system types; Alternative system: Construction Permit Application, ADEQ GP 4.03 Notice of Intent to Discharge, Engineered System Design Plans, list of equipment/materials, Operation and Maintenance Plan, ADEQ Site Investigation Report Form, and NCERA Form 310; Detailed site plan required including driving directions to the parcel; No building, manufactured home, or meter-loop permit will be issued elsewhere until the septic system is approved and documented. If your project isn't listed, confirm with Navajo County Planning & Development Services — Building & Safety Division at 928-532-6040 before starting work.

In Unincorporated Navajo County, the published Septic System Plans Review is: Fees will vary in accordance with the Delegation Agreement between Navajo County and AZDOH. Additional published fees: Septic System — Residential Conventional System Installation — $150.00; Septic System — Residential and Commercial Installation (general) — $500.00; Septic System — Residential Alternative System Installation — $800.00 starting fee; varies depending on system complexity. These are the jurisdiction's own published figures — see the fee schedule table and source citations on this page.

Unincorporated Navajo County does not publish a plan-review timeline for this permit. Contact Navajo County Planning & Development Services — Building & Safety Division at 928-532-6040 for current turnaround.

You'll need: Construction Permit Application; ADEQ General Permit Notice of Intent to Discharge (GP 4.02 conventional / GP 4.03 alternative); ADEQ Site Investigation Report Form; Onsite Findings Report (NCERA Form 310). See the required-documents checklist on this page for details on each.

Unincorporated Navajo County requires 3 inspection(s) for a septic system permit (conventional and alternative), in order: Site Suitability / Percolation Test, Trench / System Installation Inspection, Final Septic Inspection. Schedule each through Navajo County Planning & Development Services — Building & Safety Division (928-532-6040).

Apply through Navajo County Planning & Development Services — Building & Safety Division at 1100 E. Thornton Rd., Show Low, AZ 85901 (Show Low/White Mountains area office); additional area offices at 100 W. Public Works Dr., Holbrook, AZ 86025 (928-524-4100) and 2188 W. Country Club Dr., Overgaard, AZ 85933 (928-535-7110). Phone: 928-532-6040. Office hours: Monday–Thursday, 6:30 a.m. – 5:00 p.m. (Planning & Development Services main office and Show Low Building Division, per the department's Planning & Development Services page). The Permit Application Instructions document (revised January 2, 2025) lists slightly different hours for the Show Low office: Monday–Thursday, 7:30 a.m. – 6:00 p.m. Both figures are current published County sources; the department observes a 4-day (Mon–Thu) work week at all locations.. Official information: https://www.navajocountyaz.gov/289/Building-Information.

Unincorporated Navajo County, Arizona has adopted: Arizona has NO statewide mandatory building code floor for general construction — code adoption is a per-city/county authority under state enabling statutes (A.R.S. Title 11). Navajo County independently adopts and administers its own construction codes for unincorporated areas through Planning & Development Services / Building & Safety; it does NOT extend onto Navajo Nation, Hopi Tribe, or other tribal trust land, which has its own separate tribal permitting authority outside county jurisdiction. Source: Navajo County Addenda & Additions to the International Building Codes (amended 3-15-22).; 2018 International Residential Code (IRC) and 2018 International Building Code (IBC), adopted by Navajo County, EXCEPT: IRC Chapter 11 (Energy Efficiency); IRC Appendix E (Manufactured Housing Used as Dwellings); IRC § E3902; and IRC Appendices A, D, I, J, K, M, O, Q, R, S are all excluded from adoption. Source: Navajo County Addenda & Additions to the International Building Codes (amended 3-15-22), p.5 'Adopted Codes'.; 2018 International Plumbing Code — inspections are based on the 2017 IPC and cross-referenced with the 2018 Uniform Plumbing Code per the Addenda's Plumbing section. Source: Navajo County Addenda & Additions (amended 3-15-22), p.17.; 2018 International Mechanical Code, adopted alongside the 2018 IRC/IBC electrical, plumbing, and mechanical code family. Source: Navajo County Addenda & Additions (amended 3-15-22), p.5.; 2017 National Electrical Code (NEC) — electrical inspections are based on the 2018 IRC/IBC and referenced with the 2017 NEC. Source: Navajo County Addenda & Additions (amended 3-15-22), pp.5, 17.; Prior code baseline: Navajo County adopted the 2015 IBC/IRC effective June 11, 2019 (replacing a 2006 IBC edition, after the county's ISO Public Protection Classification rating was threatened with a downgrade for an out-of-date code); the county subsequently updated to the current 2018 IRC/IBC family reflected in the March 2022 Addenda & Additions. Source: White Mountain Independent, 'Navajo County updates building code' (wmicentral.com).; Building official has discretion to require an Arizona-registered architect/engineer stamp for any commercial-use structure, and for steel, log, or post/pole-and-beam construction, at the discretion of the Technical Advisory Board and Board of Supervisors. Source: Navajo County Addenda & Additions (amended 3-15-22), p.6.; Commercial buildings exceeding 3,000 sq ft of floor area intended for continuous occupancy of more than 20 persons must be designed and stamped by an engineer registered by the Arizona Board of Technical Registration, per A.R.S. § 32-144. Source: Navajo County Construction Permit Application Instructions (revised January 2, 2025).; Where a conflict exists between codes adopted by Navajo County or the State of Arizona and the Addenda and Additions, the more restrictive provision governs; the Navajo County Technical Advisory Board acts as the Board of Appeals. Source: Navajo County Addenda & Additions (amended 3-15-22), p.5.. Local amendments apply — see the Unincorporated Navajo County overview page for the full list.

10 to 120 minutes-per-inch (MPI), or a Soil Absorption Rating (SAR) of .2 or higher, without interference from groundwater or an impermeable confining layer within a 5-foot minimum separation. Source: Navajo County Construction Permit Application Instructions (revised January 2, 2025).