Industrial Wastewater
NEW: Report Water Pollution Concerns Here
Use the above link to report concerns related to water pollution. Submitted complaints are reviewed on an ongoing basis and will be investigated in accordance with the potential environmental harm and risk to public safety.
If you are representing a municipality and you are reporting a bypass, use the reporting instructions found on the Bypass Reporting for Municipalities webpage.
If your complaint is an environmental emergency, call DEEP's Emergency Response Unit 24 hours a day at 866-DEP-SPIL (866-337-7745) or 860-424-3338. Please see DEEP's Reporting Environmental Concerns and Problems webpage for additional reporting guidance.
NEW: Online Noncompliance Reporting
Effective December 1, 2023, DEEP’s Water Permitting and Enforcement Division (“WPED”) is receiving noncompliance notifications and follow-up reports required under RCSA Section 22a-430 electronically using a web-based platform. The online noncompliance notification and report forms should be used by facilities with discharge permits issued by WPED to report instances of permit noncompliance including but not limited to effluent limit violations, equipment malfunctions, spills, and bypasses. These forms do not replace DEEP’s 24-hour/day Emergency Response Unit call hotline.
Submit a notification of noncompliance here.
Submit a noncompliance follow-up report here.
How is industrial wastewater regulated in Connecticut?
Industry in Connecticut provides manufactured products and services sold in Connecticut and throughout the world. Wastewater generated from industrial activities can contain pollutants such as BOD (biochemical oxygen demand), suspended solids, nutrients, heavy metals, oils and greases, and other toxic organic and inorganic chemicals. If left untreated, these pollutants can cause serious harm to the environment.
The Department of Energy and Environmental Protection (DEEP) regulates the discharge of industrial wastewater to the ground water, surface water, and to sewage treatment plants through permitting programs. Discharge limits and requirements for treatment, monitoring and reporting, designed to protect the waters of the state from pollution, are specified in all permits.
Two types of permits are available for industrial wastewater discharges:
- Individual permits are issued directly to an applicant and are customized for a company's activities based on flow and the pollutants contained in the discharge.
- General permits cover a specific category of discharge and are issued to authorize similar minor activities by one or more applicants.
DEEP Permits and Licenses page for Wastewater Discharges
Inspection Guidance for NPDES and Pretreatment Permittees
Learn more about how to comply with your permit
Reissuance of the General Pretreatment Permit for Significant Industrial User Discharges to Publicly Owned Treatment Works
The General Pretreatment Permit for Significant Industrial User Discharges to Publicly Owned Treatment Works (“SIU GP”) regulates the following discharges from Significant Industrial Users (“SIU”) to a Publicly Owned Treatment Works (“POTW”):
-Metal Finishing Wastewater.
-Process and Non-process Wastewater that is not subject to Categorical Pretreatment Standards.
-Dewatering Wastewater.
-Remediation Wastewater.
-Temporary and Short-Term Discharges.
-Emergency Discharges lasting less than 30 days.
The Water Permitting and Enforcement Division (“WPED”) published the reissuance package for the SIU GP on April 28, 2025 for public comment. Public comments will be accepted from April 28, 2025 to May 28, 2025 to allow stakeholders adequate time to review and provide feedback on the proposed general permit.
The SIU GP is projected to be reissued on October 31, 2025. This date is subject to change, dependent on feedback received during the public comment period. The current version of the SIU GP continues in effect until the permit is reissued. Once reissued, the permit will allow time for facilities to submit their renewal registration.
Renewal registrations are not required at this time and should not be submitted. The new registration materials and website links will be posted allowing Permittees time to familiarize themselves with the new process. All renewal registrations submitted before the permit is reissued will be automatically rejected and any associated fees will not be refunded or carried forward.
Please periodically check back for updates on the permit reissuance.
-Current SIU GP
-April 28, 2025 Notice of Tentative Determination
Reissuance of the General Pretreatment Permit for Non-Significant Industrial User Discharges to Publicly Owned Treatment Works
Formerly called the “Miscellaneous Industrial Users General Permit" or “MIU GP”
The General Pretreatment Permit for Non-Significant Industrial User Discharges to Publicly Owned Treatment Works (“Non-SIU GP”) regulates the following discharges from an Industrial User (“IU”), which is not a Significant Industrial User (“SIU”), to a Publicly Owned Treatment Works (“POTW”):
-Process and Non-process Wastewater that is not subject to Categorical Pretreatment Standards.
-Dewatering Wastewater.
-Remediation Wastewater.
-Short-Term Discharges from petroleum underground storage tank replacement.
-Emergency Discharges lasting less than 30 days.
The Water Permitting and Enforcement Division (“WPED”) published the reissuance package for the Non-SIU GP on April 28, 2025 for public comment. Public comments will be accepted from April 28, 2025 to May 28, 2025 to allow stakeholders adequate time to review and provide feedback on the proposed general permit.
The Non-SIU GP is projected to be reissued on October 31, 2025. This date is subject to change, dependent on feedback received during the public comment period. The current version of the MIU GP continues in effect until the permit is reissued. Once reissued, the permit will allow time for facilities to submit their renewal notification.
Renewal notification forms are not required at this time and should not be submitted. The new notification materials and website links will be posted allowing Permittees time to familiarize themselves with the new process. Any notification form submitted prior to the reissuance of the permit will not be processed as a renewal.
Please periodically check back for updates on the permit reissuance.
-Current MIU GP
-April 28, 2025 Notice of Tentative Determination
Reissuance of the General Permit for the Discharge of Dewatering and Remediation Wastewaters
The General Permit for the Discharge of Dewatering and Remediation Wastewaters (“the remediation general permit”) regulates the discharge of dewatering and remediation wastewaters to surface waters and publicly owned treatment works.
The Water Permitting and Enforcement Division (“WPED”) published the reissuance package for the remediation general permit on August 1, 2024 for public comment. A public comment period from August 1, 2024 to September 28, 2024 was provided to allow stakeholders adequate time to review and provide feedback on the proposed general permit. During this period, WPED received significant comments from the regulated community, professional organizations, and concerned citizens.
While a March 1, 2025 reissuance date had been projected, WPED is continuing to evaluate public comments and suggest revisions to the draft permit in response to the feedback received. The current version of the remediation general permit continues in effect until the permit is reissued. Once reissued, the permit will allow time for facilities to submit their renewal registration.
Renewal registrations are not required at this time and should not be submitted. The new registration materials and website links will be posted allowing permittees time to familiarize themselves with the new process. All renewal registrations submitted before the permit is reissued will be automatically rejected and any associated fees will not be refunded or carried forward.
Please periodically check back for updates on the permit reissuance.
-Current groundwater remediation general permit
-August 1, 2024 Notice of Tentative Determination
Reissuance of the Comprehensive General Permit for Discharges to Surface Water and Groundwater
The Comprehensive General Permit for Discharges to Surface Water and Groundwater (“Comprehensive GP”) regulates the discharge of the following wastewaters to surface water and groundwater:
-Non-contact cooling or geothermal heat pump water
-Water treatment wastewater
-Hydrostatic pressure testing of natural gas and petroleum tanks and pipelines wastewater
-Potable water system maintenance of tanks and pipelines wastewater
-Fire suppression testing wastewater
-Hydrant flushing wastewater
-Boiler blowdown wastewater (to groundwater only).
The Water Permitting and Enforcement Division (“WPED”) published a Notice of Tentative Determination for the Comprehensive GP reissuance on September 18, 2024 for public comment. During the comment period from September 18, 2024 to October 18, 2024, WPED received public comments from the regulated community including three petitions for a public hearing. WPED is reviewing the public comments and a new draft Comprehensive GP will be publicly noticed in the future. The draft Comprehensive GP publicly noticed on September 18, 2024 was withdrawn by DEEP on February 13, 2025.
The current Comprehensive GP was issued on April 1, 2023 and shall remain in effect until April 1, 2026 pursuant to section 22a-6aa of the Connecticut General Statutes. DEEP will publicly notice a new draft Comprehensive GP during 2025 incorporating public comments and suggested revisions from the mediation proceedings. Once reissued, the permit will allow time for facilities to submit their renewal registration.
Renewal registrations are not required at this time and should not be submitted. When the Comprehensive GP is reissued, the new registration materials and website links will be posted allowing permittees time to familiarize themselves with the new process. All renewal registrations submitted before the permit is reissued will be automatically rejected and any associated fees will not be refunded or carried forward.
Please periodically check back for updates on the permit reissuance.
-Current Comprehensive GP
-September 18, 2024 Notice of Tentative Determination
Issuance of the National Pollutant Discharge Elimination System General Permit for Point Source Discharges to Waters of the State from the Application of Pesticides
The General Permit for Point Source Discharges to waters of the State from the Application of Pesticides was reissued on October 22, 2024, is effective on October 22, 2024, and expires on October 22, 2029. This general permit continues to authorize the discharge of pesticide residue from the application of pesticides in state waters.
Significant Changes to the 2024 General Permit:
- Automatic permit coverage for eligible permittees that are also required to obtain a permit from
DEEP’s Pesticide Management Division.
- Entities that apply pesticides to public water supply reservoirs, applications at or near the
shoreline of perennial or seasonal watercourse, and application of biopesticides for the control of
aquatic pests not otherwise required to be authorized under Section 22a-66z of the Connecticut
General Statutes, are required to submit and receive approval of registration.
- Additional narrative conditions for technology based and water quality-based effluent limitations.
- Increased visual monitoring requirements.
- The reporting requirements have been updated to reflect the new online noncompliance reporting
platform.
The general permit can be obtained here. The factsheet can be obtained here. Section 9 of the factsheet includes a summary of changes to the 2024 permit. The Department’s Response to Comments document is accessible here.
Issuance of the National Pollutant Discharge Elimination System & State General Permit for the Discharge of Swimming Pool Wastewater to Surface and Ground Waters of the State
The Swimming Pool Wastewater Discharge General Permit was reissued on July 10, 2024, is effective on August 1, 2024, and expires on July 31, 2029. This general permit continues to authorize the discharge of swimming pool wastewater from public pools to surface and ground waters of the state of Connecticut. Swimming pool wastewater includes the discharge of filter backwash, maintenance pressure washing, and pool draining wastewaters to surface and ground water.
Significant Changes to the 2024 General Permit:
- Registration is no longer required and permit coverage is automatic. Discharges are required to
comply with all terms and conditions of the general permit.
- Discharges of swimming pool wastewater to a POTW or sanitary sewer are no longer authorized
under this permit. Authorization to discharge to a POTW shall be obtained by registering under
the Pretreatment Miscellaneous Industrial User (MIU GP) or Significant Industrial User (SIU GP)
General Permit.
- Criteria for tiered wastewater disposal options has been expanded to encourage preferred
disposal options for pools constructed after the issuance of this permit. Discharges to surface
water are least desirable as they present the greatest risk to public health and the environment.
- The reporting requirements have been updated to reflect the new online noncompliance reporting
platform.
- The definition of “public pool” has been expanded to include splash pads.
The General Permit can be obtained here. The Fact Sheet can be obtained here, and Section 12 of the Fact Sheet includes a summary of all the changes to the 2024 permit. The Department's Response to Comments document is accessible here.
SNC Compliance Advisory
Significant Industrial Users in Significant Non-compliance between October 1, 2022 and September 30, 2023
The Department of Energy and Environmental Protection (“DEEP”) is required to provide notice of those significant industrial sewer users (“SIUs”) that were in significant non-compliance (“SNC”) with pretreatment standards and other pretreatment requirements during the preceding federal fiscal year. DEEP has verified the SNC status of SIUs flagged on EPA’s Quarterly Non-Compliance Reports (“QNCRs”). The QNCR, generated by the United States Environmental Protection Agency (U.S. EPA), is used to determine SIUs in SNC based on the results of sampling data submitted by permittees. The facilities identified in this document were determined to be in SNC during the time-period from October 1, 2022, through September 30, 2023.
Significant Industrial Users in Significant Non-compliance between October 1, 2022 and September 30, 2023
Related Information:
List of DPH Approved In-state Commercial Environmental Laboratories
Prohibition on Acceptance and Treatment of Wastes From Hydraulic Fracturing
Facility and Wastewater Treatment System Modification (3(i) Determination in conjunction with RCSA 22a-430-3(i))
NetDMR Electronic Discharge Monitoring Reporting
Fats, Oils, and Grease (FOG) Model Program
List of Connecticut Permitted Waste Transporters
Water Permitting and Enforcement Division PFAS Roadmap (9/30/2023)
For additional information, please contact the Water Permitting and Enforcement Division at DEEP.WaterPermittingEnforcement@ct.gov.
For specific questions regarding Pretreatment permits and compliance (industrial wastewater discharges to the sanitary sewer), contact the Pretreatment group at DEEP.Pretreatment@ct.gov.
For specific questions regarding NPDES permits and compliance (industrial wastewater discharges directly to surface water), contact the NPDES group at DEEP.IndustrialNPDESCompliance@ct.gov.
Content Last Updated May 13, 2025