Percolation tests and permit-ready septic designs for Arizona's fastest-growing county. 48-hour reports. Design only, so we never compete with your installer.
Start Your ProjectPinal County grew 3.7% between July 2024 and July 2025, the highest rate of Arizona's 15 counties, and its population has now passed the 500,000 mark according to the Arizona Office of Economic Opportunity. Coolidge was the state's fastest-growing city over the 2020–2025 stretch, and Maricopa, Casa Grande, and Eloy all landed in the top ten. That is a lot of new rooftops, and a large share of them sit outside any city sewer service area.
When there is no sewer main to tap, the home needs its own onsite wastewater system, and that starts with soil. Lot splits along dirt roads near Florence, manufactured homes outside Arizona City, custom builds in the foothills around Gold Canyon: these projects all begin with a percolation test and end with a county-approved septic design. We handle exactly that slice of the project. Perc Test AZ is a design-only firm, which means we never bid on the installation and your contractor never has to worry about handing work to a competitor.
Pinal County soil keeps the work interesting. The county's alluvial basins hold everything from fast-draining sandy loams to tight clays on former farmland near Coolidge and Eloy, with caliche hardpan showing up at unpredictable depths across the county. Two parcels on the same road can perc very differently, which is why lenders, buyers, and builders want measured field data instead of assumptions before money changes hands.
Septic permits here run through the county's Aquifer Protection Division, often called the Septic Program, part of Pinal County Community Development in Florence. The division works under authority delegated by the Arizona Department of Environmental Quality and permits and inspects conventional systems up to 24,000 gallons per day and alternative systems up to 3,000 gallons per day. Applications are accepted by email or by appointment. For current fees, forms, and timelines, see our step-by-step Pinal County septic permit guide. Here is the path from raw dirt to an operating system:
Arizona Administrative Code R18-9-A310 requires a qualified investigator to characterize both surface and subsurface conditions. With percolation testing, that means at least two test locations in the primary disposal area and one in the reserve area. Results go on the site investigation report the county reviews.
If the soil cooperates, we design a conventional system under the 4.02 General Permit (R18-9-E302): a septic tank with a trench, bed, chamber, or seepage pit disposal field. If a limiting condition exists, we design an alternative system under the appropriate Type 4 general permit instead.
We assemble the Notice of Intent to Discharge package for the Aquifer Protection Division, including the site investigation report, the system design, and the county's septic zoning clearance paperwork.
Once county review is complete, a Construction Authorization is issued and your licensed installer builds the system to the approved plans, with county inspection during construction.
After installation, the certificate of completion and a Request for Discharge Authorization are filed with the county. The Discharge Authorization is the document that lets the finished system operate.
Where we fit: steps one through three are our core work, and we support the paperwork through step five. Your installer builds it; we make sure what they build is already approved. Learn more about our perc and soil testing or septic design services.
Local pages for the county's busiest septic markets, plus coverage everywhere in between.
Arizona's largest-ever incorporation: San Tan Valley became a town in 2025 with roughly 117,000 residents. Subdivision edges still give way fast to unsewered acreage where every build starts with a perc test.
The town straddles the Maricopa–Pinal county line, so the reviewing agency depends on your parcel. We verify jurisdiction before we dig.
One of Arizona's fastest-growing cities, ringed by rural lots and converted farmland where clay layers make measured perc data essential.
The county's largest net gainer of new residents. Outside the sewered core, homesites on former ag ground need soil-specific designs.
Sewer-district connection is voluntary and plenty of parcels can't reach a main anyway, so septic stays standard from town lots to Superstition foothills acreage.
Utility sewer serves the master-planned core, but custom homes in the foothills build on decomposed granite where a perc test decides the design.
The county seat and home of the septic office itself. Town sewer covers the core while Hunt Highway corridor acreage builds on septic.
Arizona's fastest-growing city of the decade. Former farmland at the edges carries tight clays that make measured perc data essential.
Build far enough from a city main and Eloy sends you to a county septic permit. I-10 corridor farmland soils perc slow and reward careful testing.
The sanitary district's mains cover the community's core. Outside that boundary, affordable acreage and manufactured-home lots run on septic.
Also serving:
Septic permits in Pinal County are handled by the county's Aquifer Protection Division, also called the Septic Program, part of Community Development. The division operates under authority delegated by the Arizona Department of Environmental Quality (ADEQ).
It permits and inspects conventional systems up to 24,000 gallons per day and alternative systems up to 3,000 gallons per day, from its office at 85 N Florence Street in Florence, AZ.
Yes, a site investigation is required before a septic system can be designed or permitted. Under Arizona Administrative Code R18-9-A310, a qualified investigator (an Arizona-registered engineer, geologist, sanitarian, or certified evaluator) must characterize surface and subsurface conditions.
When percolation testing is the method used, the rule calls for tests at a minimum of two locations in the primary disposal area and at least one in the reserve area.
A conventional system operates under Arizona's 4.02 General Permit (R18-9-E302): a septic tank discharging to a trench, bed, chamber, or seepage pit, with a design flow under 3,000 gallons per day.
If soil, groundwater, slope, or lot size rules that out, an alternative system is designed under one of the other Type 4 general permits, covering technologies like pressure distribution, mound systems, and aerobic treatment units. Perc results usually decide which path your property takes.
Our part is fast: perc test reports within 48 hours of fieldwork, with the design and Notice of Intent to Discharge package prepared promptly after that.
County review time varies with workload and system type, and conventional systems generally move through review more simply than alternative designs. We format every submittal to minimize correction cycles.
If the parcel has no sewer connection available, we strongly recommend it. A perc test before closing tells you whether the lot supports a conventional system or will need a costlier alternative design.
It also flags limiting conditions like shallow caliche or tight clay before you own the problem. Many buyers make their purchase contingent on acceptable soil results.
It depends on which side of the county line your parcel sits. The Town of Queen Creek spans both Maricopa and Pinal counties, so two neighbors can answer to two different septic programs.
We confirm the reviewing jurisdiction from your parcel number before fieldwork and prepare the report and design to that county's format.
Tell us the parcel number and we handle the rest: soil testing, design, and the county paperwork. Call (602) 584-7430 or send your project details online.
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