Arizona Land: What's Different About Buying Here

Groundwater is regulated by geography, not statewide

The Arizona Groundwater Management Act of 1980 created Active Management Areas (AMAs) -- geographic zones, mapped around the state's most heavily pumped aquifers, where groundwater withdrawal is actively regulated by the Arizona Department of Water Resources (ADWR). There were originally five: Phoenix, Tucson, Prescott, Pinal, and Santa Cruz. The state has kept adding more as specific basins showed serious overdraft -- Douglas and Willcox AMAs were designated in 2022, and ADWR designated an eighth, Ranegras Plain, in January 2026 after finding that annual groundwater withdrawals there had been outpacing natural recharge by a wide margin for decades. In the original three AMAs (Phoenix, Tucson, Prescott), state law sets a management goal of "safe yield" -- withdrawing no more groundwater annually than is naturally recharged -- as a long-term target.

Outside an AMA (and outside the more limited Irrigation Non-Expansion Area category), groundwater pumping in Arizona is largely unregulated by comparison. Landowners generally aren't limited in how much groundwater they can withdraw for a reasonable, beneficial use, and a well under 35 gallons per minute pump capacity (an "exempt well," commonly used for a single home) can typically be drilled with only a notice filed with ADWR, not a permit. That's a real, consequential contrast: two parcels on the same aquifer, one just inside an AMA boundary and one just outside it, can face completely different groundwater rules. Given that the state has added three new AMAs since 2022, don't assume today's AMA map is permanent -- confirm current boundaries directly with ADWR for the specific parcel.

Assured Water Supply: a genuinely unsettled area right now

Inside an AMA, a subdivider offering six or more lots for sale generally cannot get final plat approval without demonstrating, to ADWR, a 100-year Assured Water Supply for the development -- either through a Certificate of Assured Water Supply issued directly by ADWR, or by connecting to a water provider that ADWR has separately designated as having an Assured Water Supply. The applicant has to show that the proposed supply is physically, continuously, and legally available for a full century, and larger subdivisions require a full hydrologic study to back that up.

This program is not settled policy right now. In June 2023, an updated ADWR groundwater model projected substantial long-term unmet demand within the Phoenix AMA, and the state stopped issuing new Certificates of Assured Water Supply based on groundwater there -- a real disruption to subdivision approvals across Maricopa and Pinal counties. In April 2026, a Maricopa County Superior Court judge ruled against ADWR in a homebuilders' lawsuit, finding that the specific standards ADWR used to apply that model (reported as the "Unmet Demand Rule" and "Depth-to-Water Rule") were adopted without required rulemaking procedure, and enjoined ADWR from relying on them; ADWR has said it intends to appeal. Separately, the legislature's Ag-to-Urban program (effective September 2025) now lets holders of certain agricultural groundwater rights in the Phoenix and Pinal AMAs permanently retire irrigated farmland for credits a developer can apply toward the 100-year physical-availability requirement. Treat all of this as actively moving: whether a specific subdivision can currently obtain a Certificate of Assured Water Supply, and on what basis, needs to be confirmed with ADWR directly, not assumed from any general description -- including this one.

Buying subdivided land: the Public Report

Separate from ADWR's water-supply program, Arizona's Department of Real Estate (ADRE) regulates the sale of subdivided land under Title 32 of the Arizona Revised Statutes. Anyone offering six or more lots, parcels, or fractional interests for sale generally has to obtain a subdivision Public Report (sometimes called a Disclosure Report) from ADRE before advertising or selling any of them. The report is meant to give a buyer the material facts about the subdivision -- utilities, roads and drainage, easements, and the status of the water supply, including whether the subdivision sits inside an AMA and, if so, whether it has the required Certificate of Assured Water Supply or an equivalent provider designation.

If you're buying a lot in a platted Arizona subdivision, ask for the Public Report and read the water-supply section specifically -- it should tell you which of these water-adequacy standards actually applies to that lot and whether it's been met, which is a more direct answer than trying to work it out yourself from the AMA map.

Zoning: set by the county

Arizona has no statewide zoning code. County planning and zoning authority comes from Title 11, Chapter 6 of the Arizona Revised Statutes, which requires each county's board of supervisors to plan for growth and gives it authority to adopt and enforce its own zoning ordinances through a county planning and zoning commission. As with most states run this way, allowed uses, minimum lot sizes, and subdivision review thresholds vary from county to county -- confirm directly with the specific county planning department for the specific parcel and intended use.

Septic: state program, county-delegated permitting

On-site wastewater (septic) systems in Arizona are regulated under the Aquifer Protection Permit program administered by the Arizona Department of Environmental Quality (ADEQ), which covers on-site systems under general permits set out in state rule for conventional septic tank-and-leach-field systems as well as alternative technologies. ADEQ has delegated authority to issue these permits to each of Arizona's 15 counties, which handle the actual permit review, site evaluation, and inspection on ADEQ's behalf in most cases.

In practice this means the office you'll actually deal with for a septic permit is the county health or environmental services department, not ADEQ directly -- though ADEQ retains program oversight and is the agency to check with if a specific county's delegation status is unclear. See our national guide to septic systems and perc tests for how the underlying design-and-approval process works.