CT DEEP Issues 2025 General Pretreatment Permits for Industrial Wastewater Discharge

Environmental Consulting

November 20, 2025

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The Connecticut Department of Energy and Environmental Protection (CT DEEP) issued two General Pretreatment Permits for Industrial Wastewater Discharge on October 29, 2025. These General Permits replace the versions issued in 2020. These General Permits were established to provide consistent regulatory oversight and effective environmental protection and to protect municipal wastewater infrastructure, safeguard human health, and preserve water quality throughout the State of Connecticut.

General Permit for SIUs

The General Pretreatment Permit for Significant Industrial User, Dewatering, and Remediation Discharges applies to Significant Industrial Users (SIU) discharges of metal finishing wastewater, process and non-process wastewater from tumbling and cleaning and non-destruct testing associated with metal finishing operations that is not subject to the US Environmental Protection Agency’s (EPA) Categorical Pretreatment Standards, dewatering wastewater, remediation wastewater, short-term discharges, and emergency discharges lasting less than 30 days. SIUs are facilities that have on-site discharges to which any provision of the National Pretreatment Standards: Categorical Standards (under 40 CFR 403.6 and 40 CFR Chapter I, Subchapter N) apply, discharge an average of 25,000 gallons per day of process wastewater to a publicly owned treatment works (POTW), contribute process wastewater that makes up 5% or more of the average dry-weather hydraulic or organic capacity of the POTW treatment plant, or are designated a SIU by CT DEEP.

Facilities registering under the General Permit for SIUs must consider Connecticut’s requirements for coastal area management and permitting, endangered and threatened species, aquifer protection, conservation and preservation, and designation of wild and scenic rivers.

The General Permit for SIUs requires registrants to submit a notification form that includes the following:

Information about the facility, including a site plan and line and process flow diagrams
Information about the POTW receiving discharges from the facility, and their approval to discharge
Details of the types and quantities of wastewater to be discharged
Description of treatment processes at the facility
Plans and specifications for wastewater treatment systems, certified by a Professional Engineer (P.E.) licensed in Connecticut
Description of substances that are or may be in the wastewater
Results from recent discharge sampling for parameters which are determined based on facility operations
A completed CT DEEP NetDMR Subscriber Agreement form
Certification that the information provided is factual and accurate

Facilities that operated under the 2020 General Permit for SIUs and have made no significant changes may be eligible to submit a “Certification of No Change” and an abbreviated application package.

Facilities operating under the General Permit for SIUs will be required to conduct monitoring for wastewater flow and pH. New pH effluent limits of 5.5 – 10.0 apply, though facilities permitted under the 2020 General Permit for SIUs have two years to comply with these limits. There are also requirements to conduct sampling; the parameters are industry-specific. Discharge monitoring reports (DMRs) must be submitted electronically to CT DEEP. Facilities must implement industry-specific best management practices (listed in the permit) for wastewater management.

Under the General Permit for SIUs, facilities (with the exception of Dewatering and Remediation Wastewater Discharges) are required to prepare an Operations & Maintenance (O&M) Plan to ensure effective performance of wastewater systems and adherence to procedures, as well as a Spill Prevention and Control Plan that describes measures taken to control unplanned releases of hazardous substances. Facilities conducting metal finishing operations must have a certified Solvent Management Plan in place. Facilities in certain industrial categories must retain a qualified professional with experience in wastewater treatment facilities and knowledge of PFAS sources and sampling methods to develop and implement a PFAS Source Identification and Reduction Plan (PFAS Plan) within the first two years after registering under the General Permit. PFAS status reports must be submitted semi-annually with the facility’s January and July DMRs.

General Permit for Non-SIUs

The General Pretreatment Permit for Non-Significant Industrial User Discharges to Publicly Owned Treatment Works applies to non-SIUs who discharge process wastewater from twenty categories of operations (including but not limited to wastewater from commercial laundries, contact and non-contact heating and cooling water, food processing including breweries and distilleries, photographic processing, water treatment, air compressor and boiler blowdown, fire suppression system testing, and vehicle maintenance).

Registration under the General Permit for Non-SIUs requires submittal of a notification form that includes the following:

Information about the facility
Information about the POTWs receiving discharges from the facility
Details of the types and quantities of wastewater to be discharged
Description of treatment processes at the facility
Description of substances that are or may be in the wastewater
Results from discharge sampling for parameters that include temperature, pH, organics, hexavalent chromium, cyanide, oil and grease, residual chlorine, polyfluoroalkyl substances (PFAS), and other pollutants based on facility operations
Certification that the information provided is factual and accurate

Facilities operating under the General Permit for Non-SIUs will need to monitor wastewater flow and pH, conduct sampling, and comply with effluent limits. Sampling frequency ranges from monthly to annual and is based on facility operations and volume of discharge. Facilities must implement industry-specific best management practices (listed in the permit) for wastewater management. Facilities must also prepare an O&M Plan and a Spill Prevention and Control Plan. Facilities in certain industrial categories must retain a qualified professional with experience in wastewater treatment facilities and knowledge of PFAS sources and sampling methods to develop and implement a PFAS Plan within the first two years after registering under the General Permit. PFAS status reports must be submitted annually by July 31.

General Permit Registration

Registration under both of the new General Permits begins on December 1, 2025. Registration forms will be available from CT DEEP at that time.

Facilities that were previously covered under the 2020 General Permits must register within 90 days (i.e., by March 1, 2026). Interim permit coverage is granted by CT DEEP, provided a timely registration is received.
New facilities in need of coverage under the General Permit for SIUs must register 180 days (6 months) prior to the date of a covered discharge.
New facilities in need of coverage under the General Permit for non-SIUs must submit a notification at least 60 days prior to the date of initiating a covered discharge.
Facilities registering for coverage under the General Permit for SIUs must pay a fee ranging from $1,000 to $6,250, based on the type of coverage requested. Registration under the General Permit for Non-SIUs does not require payment of a fee to CT DEEP (POTWs may charge fees independently).

Don’t want to be left all wet?

We can help! Trinity’s team of experts understands that General Permit registration is opening soon, applications require a lot of information, and the deadlines are tight. Our New England-based team offers consultations, regulatory guidance, and registration support to help industrial facilities: