Do drywells still need to be registered in Arizona?

Use the current UIC inventory requirements rather than relying on an old state drywell registration number. The well’s classification, present owner and regulatory jurisdiction determine what inventory and management steps apply.

Effective October 15, 2025, EPA transferred primary enforcement authority (called primacy) for Class I–VI wells to Arizona, except those on Indian lands. ADEQ's drywell page says ADEQ is now the primary regulatory agency for the UIC program, citing A.A.C. R18-9-601 et seq. and 40 CFR 147.150. The Class V inventory EPA had built moved to ADEQ as well.

Use ADEQ’s current inventory process for wells under its jurisdiction, and confirm the responsible authority for tribal lands or other exceptions.

### Why a drywell counts as a Class V well

EPA groups wells that inject non-hazardous fluids into or above underground sources of drinking water into Class V, and it lists stormwater drainage wells as a main example. Arizona's drywells fit. The well’s use and classification determine the applicable UIC requirements. Basics are in what a drywell is.

ADEQ says a person who owns an existing or proposed Class V well must register it, and that wells must be registered and managed in myDEQ, ADEQ's online portal. The EPA's Federal Register notice on Arizona's primacy explains the model: qualifying Class V wells are "authorized by rule." That means no individual permit is needed to operate. Instead the operator submits information describing the injection activity, the location, the operating status and operator contact information.

Some details from ADEQ's page and program description that matter to owners:

• The registration is valid for the life of the well, until it is plugged and abandoned. There is no yearly renewal on ADEQ's page.
• Fees exist. Ask ADEQ which registration or ownership-transfer fees apply and use its current fee schedule.
• Golf course wells are treated differently. Class V wells used with golf course maintenance do not need to be registered, but wells that take stormwater mixed with reclaimed wastewater or groundwater from manmade bodies of water at golf courses, parks and residential areas must be.
• ADEQ can ask for more. The program description notes that the ADEQ director may require the owner of any Class V well authorized by rule to apply for an individual or area permit. Most stormwater drywells stay under the rule, but a drywell that takes in something it should not can change that.

ADEQ lists a groundwater permits contact on its drywell page for questions about your specific well. The page also links ADEQ's guidance documents on design, maintenance, inspection and decommissioning, which are worth downloading for your files.

Do not confuse the two. UIC inventory and aquifer-protection permitting are different questions. Ask ADEQ which exemptions or permits apply to the water entering this particular well; stormwater registration does not authorize contaminated discharges. Where hazardous substances or motor fuels are used, stored, loaded or treated in the area draining to a drywell, ADEQ's older drywell investigation guidance says the drywell needs an investigation and an aquifer protection permit, either a general permit or an individual one. If your property has a fueling area, a chemical yard or a wash bay draining toward a drywell, that is worth a conversation with an environmental consultant.

### Why the county still asks for proof

Drywell paperwork also appears in local plan review. Maricopa County's commercial drainage requirements say that when drywells drain a retention basin, each one needs a constant head percolation test with the results sent in at as-built stage, plus verification of drywell registration with the appropriate federal or state agency.

### Three things people get wrong

"An older program changed, so I do not need to check registration." Past program changes do not establish current compliance. ADEQ’s page says owners of existing or proposed Class V wells must register them, subject to the applicable classification, exemptions and jurisdiction.

"Registration means the drywell has been inspected and approved." Registration is an inventory. ADEQ's program description describes the authorized-by-rule model as submitting information about the well, not getting a permit or an inspection. Whether the drywell works is a separate question, covered by maintenance and inspection and the drain-down test in how long water can stand in a retention basin.

"That is the tenant's problem." ADEQ's registration language speaks to the person who owns the well. Who pays for upkeep is decided by the lease, and commercial plumbing repairs: tenant or landlord explains how leases usually split that up. The registration itself follows the owner.

### How cities check up on drywells

Local governments are also watching these systems. The City of Phoenix says that since July 1, 2022 it has run a program to inventory, track, inspect and confirm adequate maintenance of post-construction stormwater controls for public and private projects of one acre or more, and that applicable projects get a site inspection within one year of construction completion. Since March 1, 2024 those projects also submit a site-specific maintenance plan. Drywells are on that list of controls. So a drywell can come up in a city inspection even if nobody has looked at the state registration in years.

1. 1Get the as-builts. The developer's civil engineer submitted drywell locations and test results when the site was approved.
2. 2Ask the previous owner or property manager for registration numbers or confirmation emails.
3. 3Check in myDEQ. ADEQ says wells are managed there.
4. 4Call ADEQ's groundwater permits contact listed on the drywell page if the trail goes cold.
5. 5Update the record when ownership changes. ADEQ's program description describes a transfer process for existing wells.

Better to find a gap now than during a sale or a plan review. The paperwork is simple when you know where to look. If you buy, sell or refinance a commercial property with drywells, put registration on the due diligence checklist next to the inspection reports. For what ADEQ expects once the well is in service, see how to inspect and maintain a commercial drywell. If a drywell has stopped draining, read can a plugged drywell be cleaned or must it be replaced.