Permits & Process · Updated August 2026
Coconino County Septic Permit Guide
As of August 2026, nearly every new septic system in Coconino County — and most full replacements — requires a Notice of Intent to Discharge filed under the Arizona Department of Environmental Quality's Type 4.02–4.22 general permit, plus a percolation test to confirm your soil type. Flagstaff Septic Pros can match you with a local contractor who handles this process routinely.
Who Regulates Septic Permits Here — and Why It's Two Agencies
Septic system permitting in Coconino County runs through two layers: the Arizona Department of Environmental Quality (ADEQ), which sets the statewide general permit program onsite wastewater systems fall under, and Coconino County itself, whose Community Development / Environmental Quality office is the local point of contact for application intake and review in this area. Most homeowners deal with both indirectly — your contractor or septic designer typically handles the actual filing.
This is a separate question from contractor licensing. Who's allowed to design and file your permit paperwork is a different topic from who's licensed to physically install or repair your system — see our installation hub for the CR-41 licensing note.
The Notice of Intent to Discharge (NOI)
The Notice of Intent to Discharge is the actual application that places your septic system under ADEQ's Type 4 general permit — the category covering most single-family onsite wastewater systems under 3,000 gallons per day of design flow, which is what a typical home falls under. It includes your system's design (tank size, drainfield or engineered-system layout, siting relative to wells and property lines) and is what legally authorizes installation once approved.
For a conventional system, the NOI is comparatively straightforward. For an engineered or alternative system — the kind many Mountainaire lots need, per our conventional vs. engineered guide — the design and review process is more involved, because the system itself is more complex and typically requires an engineer or certified septic designer's sign-off.
The Perc Test
A percolation ("perc") test measures how quickly your soil absorbs water — the single piece of data that actually determines whether your lot supports a conventional leach field or needs an engineered/alternative system. It's typically required as part of the design package submitted with your NOI, and it's performed by a licensed septic designer or a specialized perc-testing firm, not by a general contractor.
National cost guides put a perc test at $300–$1,500 depending on the test type. One Arizona-specific source puts the statewide AZ average closer to $1,300, with a typical range of $750–$1,900 and machine-dug testing running up to $3,000 — worth knowing before you budget, since the national low end may understate what this specific test costs in Arizona. Simple single-hole tests can run as low as $300. See the full breakdown on our cost guide.
Permit Fees
Coconino County — not ADEQ directly — handles conventional septic permitting for most of this area: the county holds ADEQ's delegation to administer conventional systems (and some alternative systems, up to 3,000 gallons per day) on its own. The county's published Environmental Quality Fee Schedule (effective September 1, 2021, current as of this guide's last check) sets a Residential Conventional System Permit at $548 — the figure that applies to a typical single-family home's septic permit in this area.
- Residential Conventional System Permit: $548
- Residential Conventional Redesign Review: $275
- Conventional System Repair Permit: $214
ADEQ's own statewide fee schedule lists separate, higher figures for its general permit — a first permit at $1,811.28, each additional at $755.40, up to a $5,586.19 maximum. Those apply to systems and areas ADEQ administers directly rather than to a county-delegated residential conventional permit, so they're not what a typical Flagstaff-area homeowner actually pays. Confirm the exact fee for your specific project with Coconino County Community Development (928-679-7120) before budgeting for it — an engineered or alternative system falls under a different fee tier than the conventional permit above.
One thing worth ruling out explicitly: ADEQ's own schedule also lists much larger figures — up to $37,743.84 for Type 4.01 sewage collection systems and up to $11,323.68 for Type 4.23 facilities handling 3,000–24,000 gallons per day. Those apply to commercial or collection-system-scale projects, not a single-family home, and citing them here would be actively misleading — they're not relevant to a typical residential septic permit.
Realistic Timeline
Every project is different, but a rough shape of the process looks like: soil/perc testing and system design (typically the pacing item — the perc test itself can be scheduled within days to a couple of weeks, but design and engineering review for an engineered system takes longer than for a conventional one), NOI submission and ADEQ review, then installation once the permit is approved. Build in time for review cycles — this is not a same-week process for a new system, especially an engineered one. Your contractor or septic designer, who handles this routinely, is the best source for a timeline specific to your project.
Frequently Asked Questions
Do I need a permit to install or replace a septic system in Coconino County?
Yes — nearly every new septic system and most full replacements in Coconino County require a Notice of Intent to Discharge filed under ADEQ's Type 4 general permit program before work begins. A straightforward like-for-like repair (replacing a pump, fixing a baffle) typically doesn't need a new permit, but confirm with your contractor and the county before assuming.
What is a Notice of Intent to Discharge?
It's the application that puts your septic system under ADEQ's Type 4 general permit — the umbrella covering most residential onsite wastewater systems under 3,000 gallons per day. You (or, more commonly, your contractor or septic designer) file it with your system's design details before installation, and it's what makes the installation legal under Arizona's water-quality regulations.
When is a perc test required in Coconino County?
A percolation test is required as part of the design process for essentially any new septic system, and often for a full replacement — it's what determines whether your soil supports a conventional leach field or requires an engineered/alternative system. Budget $300–$1,900 depending on the type of test and who performs it; see our cost guide for the full range.
How much does a Coconino County septic permit cost?
Coconino County's own fee schedule sets a Residential Conventional System Permit at $548 — that's the figure that applies to a typical single-family home. The county holds ADEQ's delegation to administer conventional septic permitting directly, so ADEQ's own separate general-permit schedule (higher figures, up to $5,586.19) doesn't apply to a standard residential permit here. Confirm the exact fee for your specific project with Coconino County Community Development (928-679-7120) before budgeting for it.
Need Help Navigating the Permit Process?
A local, CR-41-licensed contractor or septic designer can handle the NOI filing and perc test for you — get matched with one, free.