Connecticut Department of Energy & Environmental Protection

Pretreatment Program

The Pretreatment Permitting, Compliance, and Enforcement Program helps protect our public sewer systems and the environment by regulating what industrial and commercial facilities can send down the drain.

Certain businesses and cleanup sites produce wastewater that contains pollutants - like heavy metals, chemicals, oils, or other substances - that municipal wastewater treatment plants (Publicly Owned Treatment Works or POTWs) aren't designed to fully remove.

That's where the Pretreatment Program comes in. We work with industrial users and remediation sites to make sure wastewater is treated before it enters the public sewer system helping to protect local municipal wastewater treatment plants, public health, and the environment.

What the Program Does
 The Pretreatment Program issues permits, conducts compliance oversight, and enforces state and federal regulations for facilities that discharge to public sewer systems (POTWs). This ensures that harmful pollutants are treated at the source and don't disrupt treatment processes or pollute local waterways.

Our Goals
 The Pretreatment Program aims to:
  • Protect wastewater treatment plants from pollutants that could disrupt operations or damage infrastructure
  • Prevent untreated pollutants from passing through POTWs into rivers, lakes, or groundwater
  • Support water reuse by improving the quality of wastewater and sludge
  • Keep workers and communities safe by reducing exposure to hazardous pollutants in the sewer system
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Types of Dischargers Regulated Under the Pretreatment Program

The Pretreatment Program covers a range of facilities and activities that discharge non-domestic wastewater to the municipal sewer systems (POTWs). Each type of discharger has different characteristics, but all may generate pollutants that require oversight and, in some cases, pretreatment.

Below are the main categories of dischargers regulated under the program:

Industrial Users (IUs)

Industrial Users are facilities that discharge wastewater from commercial or manufacturing processes to a publicly owner treatment works (POTW). These discharges may contain pollutants like heavy metals, solvents, oils, or other chemicals that can affect treatment plant performance or water quality.

Examples include:

  • Metal finishing and plating shops
  • Food and beverage manufacturers
  • Pharmaceutical and chemical manufacturers
  • Laboratories and research facilities
Significant Industrial Users (SIUs)

A Significant Industrial User (SIU) is a specific type of Industrial User that meets any of the following criteria:

  • Discharges 25,000 gallons per day or more of process wastewater to a POTW
  • Contributes process wastewater that makes up 5% or more of the POTW's average dry-weather capacity
  • Is subject to federal categorical pretreatment standards under 40 CFR
  • Is designated as significant by the POTW or DEEP due to its potential to impact the treatment plant, worker safety, or environmental health.

SIUs are subject to additional monitoring, reporting, and permitting requirements due to their higher potential impact.

Groundwater or Soil Remediation Sites

These sites generate wastewater as part of environmental cleanup activities - often involving treatment of contaminated soil or groundwater. This discharged water may contain pollutants such as:

  • Petroleum hydrocarbons
  • Solvents (e.g., PCE, TCE)
  • Heavy Metals
  • Other site-specific contaminants
Remediation discharges may be temporary or long-term, and typically require treatment systems (e.g., air strippers, GAC filters) to reduce pollutant concentrations before discharge to the sewer.

Construction or Dewatering Projects

These projects generate temporary wastewater discharges related to construction or site preparation activities, including:

  • Dewatering of excavations, foundations, or utility trenches
  • Stormwater management during construction
  • Pumping of groundwater or accumulated surface water
While dewatering discharges are typically less complex than industrial wastewater, they may still contain suspended solids, elevated turbidity, or contaminants specific to the site. Proper management under permit conditions is essential to protect both sewer infrastructure and treatment plant performance.

Pretreatment Permitting Options

Connecticut offers both site specific individual and statewide general permits that authorizes certain types of industrial and site-related discharges to public sewer systems.

The general permits replace older, category-specific authorizations and provides a streamlined, modern approach to pretreatment regulation.

Use the Pretreatment Permit Decision Chart to determine which permit is right for you. Applying for a permit is easy. Review the eligibility requirements, complete an application, and submit the required documentation. 

Individual Permits

Covers all industrial discharges of wastewater to a POTW.

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

 

General Pretreatment Permit for Significant Industrial User, Dewatering, and Remediation Discharges (SIU GP)
Covers discharges of metal finishing, other non-categorical process, and non-process wastewaters from significant industrial users, remediation and cleanup wastewater, and construction-related dewatering discharges to POTWs. 

 

 

General Pretreatment Permit for Non-Significant Industrial User Discharges to Publicly Owned Treatment Works (Non-SIU GP)

Covers discharges of industrial process and non-process wastewater from non-significant industrial users to POTWs.

 

 

Reporting Noncompliance

Noncompliance notifications and follow-up reports required under RCSA Section 22a-430 and pretreatment permits must be submitted electronically using the online platform:
Noncompliance Notification Form
Noncompliance Follow-up Report Form

Quick Reference of Pretreatment Notification Requirements

Notifications made through the online notification system do not replace DEEP's 24-hour/day Emergency Response Unit hotline (860) 424-3338.

Noncompliance Issue

Details

Initial Notification

Follow-up Report

Permit Violations

Two times any Maximum Daily Limit

 

2 hours

5 days

Exceedance of any Permit Limit

 

24 hours

30 days

Equipment Failures/Malfunctions or Bypass

Failure or Malfunction of Monitoring Equipment

 

2 hours

5 days

Bypass of any or all of the Wastewater Treatment System

 

2 hours

5 days

Additional Resources:
Industrial Wastewater
 NetDMR Webpage
 Contact Us:
Have a question? Need help with your permit? We're here to help.

Pretreatment Program Staff:
Connecticut Department of Energy & Environmental Protection (DEEP)
Email: DEEP.Pretreatment@ct.gov

 

Content Last Updated: January 14, 2026