Well Water in Pinal County, Arizona

A different track than the Assured Water Supply fight

The hub's coverage of ADWR's stance against new groundwater-based Assured Water Supply approvals, and the 2025-2026 Ag-to-Urban legislation, applies to subdivisions -- new developments of six or more lots that need a Certificate of Assured Water Supply before they can be built and sold. An individual buyer drilling one exempt well (defined under Arizona law as pumping less than 35 gallons per minute, for uses like a single home) on an existing parcel doesn't go through that process at all. That well runs through ADWR's standard exempt-well permitting -- and in Pinal County specifically, through one extra, documented local review step first.

Pinal County's local review: mandatory for parcels five acres or smaller

Before ADWR will issue a well permit for a parcel of five acres or less in Pinal County, the Notice of Intent to Drill and a site plan must first go to Pinal County Environmental Health's Aquifer Protection Division for local review and endorsement. That review checks well siting and septic-system separation requirements specifically -- confirming the proposed well location won't sit too close to an existing or planned septic system on the same lot or an adjacent one -- before the county forwards its endorsement to ADWR for the actual state permit. Pinal County's own Environmental Health Code lists a $55 fee for this ADWR well-site endorsement/approval, separate from whatever ADWR itself charges for the permit.

The practical sequencing matters: you (or your driller) submit to the county first, wait for county sign-off on siting and septic separation, and only then does the application move to ADWR. Skipping straight to ADWR without the county step is the kind of mistake that can cost real time on a small-parcel well -- confirm the current process and fee directly with Pinal County Public Health's Environmental Health Services before assuming a larger-parcel process (which doesn't require this county step) applies to your five-acre-or-smaller lot.

Arsenic is a documented, real issue in Pinal County groundwater -- and nobody tests it for you

Separate from permitting, Pinal County groundwater carries a documented water-quality issue worth planning for: more than 40% of wells in Pinal County have been found to exceed the EPA's safe drinking-water limit for arsenic, a materially higher rate than the Arizona statewide average. The underlying cause is geological -- Pinal sits in the Basin and Range province, where arid conditions, low precipitation, and long groundwater residence times let arsenic, fluoride, and other minerals concentrate in the aquifer as water slowly moves through mineral-rich rock formations over time. Naturally-elevated fluoride and radioactive materials like radium have also been documented in Arizona groundwater generally, with Pinal County specifically flagged for radium presence.

Here's the part that makes this genuinely actionable rather than background trivia: private domestic wells are not regulated by the EPA or the State of Arizona for water quality at all. No agency tests your water, treats it, or notifies you if arsenic or another contaminant is present -- that responsibility falls entirely on the well owner. If you're buying land in Pinal County specifically to drill a domestic well, budget for an independent water-quality test (arsenic, fluoride, and general mineral content at minimum) as part of your due diligence, and don't assume a neighboring property's clean well tells you anything reliable about your own parcel's groundwater.