Underground Injection Control (UIC) Program

Subsurface Wastewater Disposal Systems

The Connecticut Department of Energy and Environmental Protection (DEEP) Underground Injection Control (UIC) Program was created under the Regulations of Connecticut State Agencies 22a-430-8 to protect the state's groundwater resources from contaminants that may adversely affect public health or degrade water quality.
Groundwater is a critical source of drinking water for communities across Connecticut. The UIC Program regulates the subsurface wastewater disposal systems and other underground injection activities.

Program Overview

The U.S. Environmental Protection Agency (EPA) established the minimum requirements for the program under the federal Safe Drinking Water Act. While EPA sets the national requirements, Connecticut is authorized to implement and enforce the program within the state.

Our mission is simple: Protect Underground Sources of Drinking Water (USDWs).

Program Goals

The UIC Program works to:

Protect underground drinking water from pathogens and harmful pollutants.
Prevent conditions that may create risks to public health.
Provide clear and consistent standards for regulated systems.

Through permitting, technical review, and compliance oversight, DEEP ensures water returned to the ground is managed responsibly.

How DEEP Administers the UIC Program

DEEP implements the program through:

Technical Review - evaluation of site conditions and engineering plans.
Permitting - establishing discharge authorization requirements.
Compliance - monitoring, maintenance, and reporting obligations.
Decommissioning - proper closure of regulated systems.

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Injection Wells

What is an Injection Well?

Injection wells are grouped into six categories. In Connecticut, DEEP regulates Class V wells.

These are typically shallow systems used to discharge non-hazardous fluids, such as treated wastewater or stormwater, into or above groundwater. Their purpose is to return water to the ground while protecting drinking water supplies.

Learn more by visiting EPA's website: Class V Wells - Injection of Non-Hazardous Fluids.

Common System Types

Systems are generally categorized by their complexity and level of treatment:

Low-Tech Systems - simple structures such as dry wells or holding tanks.
Conventional Systems - septic systems and standard subsurface disposal.
Alternative Treatment (AT) Systems - advanced technologies that provide higher levels of treatment prior to discharge.

System Complexity Levels. Low-Tech (Dry Wells). Conventional (Septic). Alternative Treatment (Advanced Technologies). Class V Injection Wells. Shallow systems used for non-hazardous fluids like treated wastewater or stormwater drainage, Underground Sources of Drinking Water (USDWs).

Who is Regulated?

The UIC Program regulates many types of facilities, including:

Municipalities - stormwater drainage structures such as dry wells.
Commercial centers - businesses discharging sanitary or process wastewater.
Residential communities - mobile home parks, condominiums, apartments.
Environmental remediation projects - reinjection of treated groundwater.

Regulatory jurisdiction depends on the total site-wide design flow and the type of treatment system.

In Connecticut, jurisdiction is determined by the type of system you have and how much water it processes daily. 1. Local Health Department Jurisdiction, small standard systems less than 2000 gallons per day, mid-sized systems 2000 to 7500 gallons per day. 2 CT DEEP Jurisdiction, large systems greater than 7500 gpd, community systems, advanced technology systems.

UIC Permitting Options

Discharges are authorized under either a General Permit or an Individual Permit, depending on the design flow, treatment technology, and project complexity.

Review the UIC Permit Chart to determine which permitting mechanism is best for your project before preparing your application.

Schedule a DEEP Site Investigation

Before submitting an application and preparing plans, applicants must schedule a site investigation with the UIC Program Supervisor.

Getting Started: Schedule the site investigations. Before preparing plans, applicants must coordinate with DEEP staff to schedule a site investigation. You must contact DEEP one week in advance to secure your timeslot.

Email us: DEEP.UICPermitting@ct.gov Subject line: "Site Testing"

Check our FAQ document for answers to frequently asked questions: FAQs

Individual Wastewater Discharge Permit

Covers all eligible discharges to groundwater, including alternative sewage treatment systems, lateral sand filters, reuse and complex or high-risk discharges.

Before applying for an individual permit, review whether your activity qualifies for coverage under a general permit — it can save you time, money, and paperwork.

See the UIC Permit Chart.

General Permits to Discharge from Subsurface Disposal Systems

General permits are designed for common discharge types and often have a faster approval process with lower fees than individual permits.

Most conventional subsurface wastewater disposal systems under DEEP jurisdiction are eligible for authorization under the General Permit.

See the UIC Permit Chart.

Need to Make a Change?

Contact the UIC Program and submit the appropriate form below before making a change to the following:

increasing wastewater flow
modifying treatment
expanding disposal areas
installing a replacement treatment system
transferring ownership
abandoning or closing a system

Unauthorized modifications to your flows or treatment systems before obtaining authorization may result in loss of permit coverage. Some changes require the submission of an updated Wastewater Management Plan or engineering designs, plans, and specs.

If you have coverage under an Individual Permit, use this form to request a modification:

Facility and Wastewater Treatment System Modification Notification and Request for Approval

If you have coverage under a General Permit, use this form to request a modification:

General Permit Form to Discharge from Subsurface Disposal Systems

An updated Wastewater Management Plan must be submitted your modification request.

Additional Resources

NetDMR Resources

DEEP NetDMR Homepage
NetDMR/CDX: EPA NetDMR Portal
Central Data Exchange: CDX Sign-in
NPDES eReporting Tool: eRule NetDMR Homepage

Mapping Resources

Impaired Waters Map: CT DEEP GIS Viewer
Map: CT DEEP GIS Open Data
Map: CT DEEP Water Quality
Map: CREST Collaborative Solar Suitability Application

Contact Us

Have a question or need help with your permit?

Email us at DEEP.UICPermitting@ct.gov

Content Last Updated: May 21, 2026