Maricopa County Wastewater Permitting Changes: What You Need to Know
As of June 24, 2026, Maricopa County no longer permits or inspects centralized wastewater treatment facilities. Oversight now falls solely to the Arizona Department of Environmental Quality (ADEQ). This change removes overlapping county review, but it doesn’t eliminate state requirements or affect Maricopa County’s onsite septic permitting process. Here’s what changed and what it means for your project.
Maricopa County no longer permits or inspects centralized wastewater treatment facilities. The Arizona Department of Environmental Quality, commonly called ADEQ, is now the sole regulatory authority for these facilities.
The change took effect on June 24, 2026, and removes a duplicate layer of county and state oversight. Centralized wastewater treatment facilities are still regulated, but facility owners and applicants now work directly with ADEQ instead of completing overlapping review and inspection processes through both agencies.
However, this change doesn’t eliminate Maricopa County’s other wastewater responsibilities. The county continues to regulate several types of water and wastewater infrastructure. Most importantly for homeowners, builders, and developers, Maricopa County still reviews, permits, and inspects onsite wastewater systems, commonly called septic systems.
If you’re planning a septic project, you’ll still need to complete the applicable county process before installation and use. Depending on the property and proposed system, this may include a soil and site investigation, septic system design, permit application, inspections, and final authorization.
What Changed in Maricopa County?
On June 24, 2026, the Maricopa County Board of Supervisors approved EROP Case ES-2025-005. The change ended the Maricopa County Environmental Services Department’s permitting and inspection program for centralized wastewater treatment facilities.
MCESD no longer accepts new applications or issues Approvals to Construct or Approvals of Construction for these facilities. All open county construction permits are being closed, regardless of where they are in the review or approval process. Applicants with active permits generally don’t need to withdraw them or submit a separate closure request. MCESD will contact them directly as needed.
The county is also closing existing operational permits for affected wastewater treatment facilities. Facility operators no longer need to submit monthly water-quality reports to MCESD, and the department will no longer conduct routine operational inspections.
This doesn’t mean these facilities are no longer regulated. Oversight now falls solely to the Arizona Department of Environmental Quality, or ADEQ. The change simply removes the additional county permitting and inspection process that previously existed alongside ADEQ’s requirements. Maricopa County’s official regulatory bulletin explains the full transition.
Why Did Maricopa County Make This Change?
Maricopa County made this change to eliminate overlapping county and state oversight. Before the change, both the Maricopa County Environmental Services Department and the Arizona Department of Environmental Quality reviewed and inspected centralized wastewater treatment facilities.
Maricopa County was the only county in Arizona operating this type of wastewater treatment engineering review program. As a result, facilities could be subject to similar reviews and inspections from both MCESD and ADEQ.
Ending the county program consolidates regulatory oversight under ADEQ. Wastewater treatment facilities are still required to meet applicable state permitting, construction, reporting, and operational requirements.
In simple terms, Maricopa County made the change to eliminate duplicate oversight. Wastewater treatment facilities now work with one primary regulator, ADEQ, instead of completing overlapping county and state processes.
Do Facility Owners or Applicants Need to Take Action?
The action required depends on whether you have an open county permit, operate an existing wastewater treatment facility, or are planning a new facility.
If You Have an Open County Construction Permit
You generally don’t need to take any action. MCESD is closing all open construction permits for affected wastewater treatment facilities, regardless of where they are in the review or approval process.
Applicants don’t need to withdraw their applications or submit a separate closure request. The department will contact affected applicants directly if any additional information or action is required.
If You Operate a Wastewater Treatment Facility
MCESD is closing existing county operational permits for wastewater treatment facilities. Operators are no longer required to submit monthly water-quality reports to the county, and routine MCESD operational inspections have ended.
However, this doesn’t eliminate the facility’s regulatory responsibilities. Applicable ADEQ permits, reporting requirements, inspections, and operational obligations remain in effect.
If You’re Planning a New Facility
Don’t submit a wastewater treatment facility application to MCESD. New facility projects should confirm the applicable ADEQ requirements early in the planning process and before beginning construction.
Depending on the project, this may include obtaining coverage under ADEQ’s Aquifer Protection Permit program and completing other required reviews or approvals. Confirming the correct regulatory path before design work is finalized can help prevent unnecessary revisions and delays.
Maricopa County’s official regulatory bulletin provides additional guidance for applicants and facility operators.
What Hasn’t Changed?
The change doesn’t mean wastewater treatment facilities are unregulated or that all Maricopa County wastewater permits have been eliminated. It only ends MCESD’s permitting and inspection program for centralized wastewater treatment facilities.
ADEQ continues to oversee these facilities at the state level. Depending on the project, its responsibilities may include:
Aquifer Protection Permits
Wastewater treatment facility plan review
Applicable construction authorization
MAG 208 conformance review
Operational oversight and inspections
Facility owners, operators, and applicants must still comply with all applicable ADEQ requirements. The change consolidates regulatory authority under one agency. It doesn’t eliminate the underlying state requirements or allow projects to move forward without the necessary permits and approvals.
What Water and Wastewater Projects Does Maricopa County Still Permit?
Maricopa County continues to permit several types of water and wastewater infrastructure. These include sewer collection pipelines, manholes, force mains, sewage pump and lift stations, drinking-water infrastructure, reclaimed-water distribution systems, and other qualifying water and sewer projects.
The responsible permitting authority depends on what the project is actually constructing. Centralized wastewater treatment facilities now fall under ADEQ, while onsite septic systems remain under the Maricopa County Environmental Services Department’s Onsite Wastewater Program. Sewer collection infrastructure also continues to go through Maricopa County.
Drinking-water and reclaimed-water projects may require approval from Maricopa County as well as other applicable agencies, depending on the project’s scope and location. Because a single development may include components overseen by different agencies, it’s important to confirm the correct permitting path before completing the design or submitting an application.
Maricopa County’s current construction permitting guidance confirms that centralized treatment facilities go through ADEQ, while septic systems and qualifying water and sewer infrastructure remain subject to county permitting requirements.
Does This Change Affect Septic Systems?
No. Maricopa County still reviews, permits, and inspects onsite wastewater systems, commonly called septic systems. These projects are handled through the Maricopa County Environmental Services Department’s Onsite Wastewater Program.
The regulatory change applies only to centralized wastewater treatment facilities. It doesn’t eliminate septic permits or change the county’s standard application and approval process for onsite systems.
Depending on the property, project, and proposed system, owners may still need a site and soil evaluation, septic system design, county review, Construction Authorization, installation inspection, and Discharge Authorization before the system can be used.
Maricopa County also continues to accept Phase I site and soil evaluations, conventional and alternative system designs, septic permit applications, alteration applications, and abandonment applications through its Onsite Wastewater Program.
The key distinction is simple: centralized wastewater treatment facilities now fall solely under ADEQ, while onsite septic systems remain under Maricopa County’s permitting and inspection process.
What This Means for Projects in Maricopa County
The permitting process now depends more than ever on what a project is actually constructing. Centralized wastewater treatment facilities now work with one regulator, ADEQ, instead of completing overlapping county and state processes. Onsite septic systems, however, still go through Maricopa County.
Other components, including sewer collection systems and certain water or wastewater infrastructure, may also continue to require county approval. This means a single development could include several components regulated by different agencies.
Misidentifying the system type or submitting an application to the wrong agency can lead to delays, added costs, and unnecessary design revisions. Before completing plans or submitting an application, property owners and project teams should confirm which agency regulates each part of the project and what approvals are required.
Ponderosa Environmental can help identify the appropriate permitting path, evaluate site conditions, and prepare septic and wastewater designs that meet the applicable requirements.
How Ponderosa Environmental Can Help
Wastewater projects can involve different systems, requirements, and regulatory agencies. Ponderosa Environmental helps homeowners, builders, and developers determine whether a project involves an onsite septic system, a centralized treatment facility, or multiple regulated components.
Our team completes soil site investigations and prepares conventional and alternative septic system designs based on the property’s conditions and proposed use. We also support commercial, community, and subdivision wastewater planning, prepare clear documentation for the appropriate regulatory agency, and help clients understand what must happen before construction can begin.
Planning a septic or wastewater project in Maricopa County? Ponderosa Environmental can help you evaluate the property, determine the appropriate permitting path, and prepare the required design documents.
Key Takeaways
Maricopa County no longer permits or inspects centralized wastewater treatment facilities.
ADEQ is now the sole regulator for these facilities.
Existing county permits for affected facilities are being closed.
Applicable state wastewater treatment requirements remain in effect.
Maricopa County continues to permit qualifying sewer, drinking-water, and reclaimed-water infrastructure.
Onsite septic systems still go through Maricopa County’s review, permitting, and inspection process.
Confirming the project type and responsible agency early can help prevent unnecessary delays, costs, and design revisions.
Frequently Asked Questions
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The Arizona Department of Environmental Quality, commonly called ADEQ, is now the sole regulator for centralized wastewater treatment facilities in Maricopa County.
The Maricopa County Environmental Services Department, or MCESD, no longer permits or inspects these facilities. -
Yes. The county permitting layer ended, but applicable ADEQ permits and approvals are still required.
The change consolidated regulatory oversight rather than eliminating it. -
Generally, no. Maricopa County is closing affected wastewater treatment facility permits.
The county will contact applicants directly if additional information or action is required. -
Yes. Onsite wastewater systems, commonly called septic systems, remain under the Maricopa County Onsite Wastewater Program.
Septic applications, plan reviews, approvals, and inspections continue. -
Yes. Maricopa County continues to permit qualifying sewer collection infrastructure, including pipelines, force mains, manholes, and sewage pump or lift stations.
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The correct permitting authority depends on the system type and project scope.
Centralized wastewater treatment facilities generally go through ADEQ, while onsite septic systems and qualifying sewer infrastructure remain under Maricopa County.
Complex developments may include components regulated by both agencies.