Underground Injection Well Registration in EPA's Pacific Southwest (Region 9)
EPA’s Pacific Southwest (Region 9) implements and enforces federal environmental laws in Arizona, California, Hawaii, Nevada, the Pacific Islands, and 148 Tribal Nations.
How to Register Injection Wells
If you own, operate or plan to construct one or more injection wells, you are required to register those features, also known as injection wells, with the Underground Injection Control program. This requirement applies to deep and shallow subsurface disposal systems as defined in 40 CFR part 144. Compliance with the federal Underground Injection Control (UIC) regulations includes fulfilling two basic requirements: (1) - register injection well(s) and (2) - do not use injection wells in a manner that will contaminate underground sources of drinking water.
These instructions and e-Form were developed to assist injection well owners in Arizona, California, Hawaii, and Indian Tribes of the desert southwest comply with the federal UIC regulations. Other state and local regulations may apply. See the regulations at 40 CFR part 144 for more information, at the U.S. Government Printing Office.
Frequently Asked Questions
My runoff discharges to a swale, pond or ditch. Is this injection?
If there is no subsurface (buried) discharge component to the system, then it is not subject to UIC requirements, however it may be subject to Clean Water Act requirements or other water protection regulations.
The injection well serves a single family home. Do I have to register the well?
Injection wells serving single family homes do not have to submit inventory information unless they are used by a home-based business, such as car repair, pet boarding, medical services or other businesses that generate a liquid waste stream that is to be disposed underground.
I have a septic system with multiple leachfield lines. Does each leachfield pipe count as a different injection well?
No, if all of the leachfields receive effluent from the same septic tank or other treatment device, they count as components of one injection well or subsurface fluid distribution system.
Do I need an EPA permit to operate my Class V well?
Not necessarily. Most Class V wells are Authorized by Rule in EPA Region 9, meaning that the Class V injection well could operate without a permit if certain conditions are met, as described on Federal Requirements for Class V Wells. After submitting well inventory information (using the form below), EPA Region 9 will make a determination if the well(s) can be Authorized by Rule. Note that injection activities may be subject to state and local permits, as described below.
Is registering the injection well my only obligation?
Some injection activities are subject to state and local requirements and/or permits. Single-family onsite sewage systems are generally regulated by county environmental health agencies. Large capacity sanitary waste disposal and industrial discharges may be regulated by local or state water quality agencies. If your injection well(s) are subject to a discharge permit from the state, please list that permit number in the comments box to help reduce duplicative requirements.
Depending on multiple factors, such as your location in relation to drinking water supply wells or the type of injectate, your injection well(s) may be subject to additional federal requirements. These requirements may include sampling, characterization, permitting or closure of injection wells. Shallow injection of hazardous waste, untreated sewage and motor vehicle repair fluids is prohibited except in ongoing remedial actions overseen by regulatory agencies. See the regulations for more information. IMPORTANT: You must notify EPA if the ownership, well operating status or injectate changes.
How does EPA use the information?
EPA will use this information to notify you of applicable regulatory requirements or best management practices to prevent contamination. EPA shares the data with other water quality agencies, public water supply agencies, and in response to Freedom of Information Act requests for the data.
Do I need an EPA permit for Aquifer Storage & Recovery (ASR) wells or other wells that inject into the vadose zone in California?
EPA Region 9 allows ASR and other injection wells in California that inject into the vadose zone—such as Aquifer Recharge (AR), Aquifer Remediation, or Saline Water Barrier Intrusion wells—to operate under the federal Class V “Authorization by Rule” (i.e., without an individual EPA UIC permit) if both of the following are true:
- The well meets the federal Class V Authorization by Rule requirements (see above: “Do I need an EPA permit to operate my Class V well?”).
- The well is authorized by the Regional Water Quality Control Board (RWQCB) and the associated ‘Place ID’ number is provided to EPA.
State authorization pathways for wells that inject into the vadose zone include:
- ASR wells must meet the requirements of General Order WQ 2012-0010 (pdf).
- Other UIC wells that inject into the vadose zone but do not meet the requirements of General Order WQ 2012-0010 must submit a report of waste discharge to the RWQCB.
When the RWQCB determines a well complies with General Order WQ 2012-0010 or the Waste Discharge Requirements (WDR) program, it assigns a ‘Place ID’ number. EPA determined that wells covered under these programs meet the Authorization by Rule regulatory threshold and will process the well registrations accordingly through EPA Injection Well Inventory Form (below) once the ‘Place ID’ number is provided.
More information about AR and ASR wells can be found on Aquifer Recharge and Aquifer Storage and Recovery.
Is an abandoned drinking water well classified as a Class V UIC well?
An abandoned drinking water well may be classified as a Class V UIC well if the well is not intended for future use and has not been properly plugged and abandoned. The same classification can apply to other improperly abandoned wells, such as abandoned agricultural production wells.
Improperly abandoned wells pose a risk to groundwater by creating a direct pathway for surface contaminants to reach aquifers. If such a well is identified, it must be registered with EPA using the Injection Well Inventory Form below. It is also critical to properly plug the well to seal pathways between potential sources of contamination and aquifers.
Below are resources you can use to help properly plug and abandon wells:
- Arizona Department of Water Resources: Well Abandonment Handbook, September 2008 (pdf)
- California Department of Water Resources: Part III. Destruction of Water Wells
- Nevada Abandoned Wells Fact Sheet (pdf)
Source water assessment programs (SWAPs) can help identify potential improperly abandoned wells in the assessment area. If you have any questions about the SWAP program, please reach out to r9iWells@epa.gov.
Do you need to register a drywell in Arizona with EPA?
No. As of October 15, 2025, Arizona has authority over all Class I -VI injection wells. EPA has transferred all AZ UIC Class V inventory, except for inventory on Indian lands, to the Arizona of Department of Environmental Quality (ADEQ). To register a drywell, or any UIC Class V well in the State of Arizona, please visit ADEQ’s UIC Class V Well Inventory website.
Injection Well Inventory Form
* Indicates a required field. After submitting this form, a confirmation email with the submitted form data will be sent to the address provided.