Subsurface Sewage Treatment and Disposal Systems (Septic Systems)

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.

What is a septic system?

A septic system treats and disperses wastewater from individual or small numbers of homes and commercial buildings. The type and/or size of the septic system, determines what agency has regulatory authority.


A "conventional subsurface sewage treatment and disposal system" - consists of a house sewer, septic tank followed by a leaching system, any necessary pumps or siphons, and any ground water control system on which the operation of the leaching system is dependent.

A "community subsurface sewage treatment and disposal system" - consists of one subsurface sewage disposal system serving two or more residential buildings, regardless of system size.

An "alternative treatment system" - consists of a sewage treatment system serving one or more buildings that utilizes a method of treatment other than a subsurface sewage disposal system and that involves a discharge to the groundwaters of the state.

Type/Size of System

Contact Information

Systems regulated by the Department of Energy & Environmental Protection (DEEP)

Conventional systems with design flows greater than 7,500 gallons per day, including sites where multiple smaller systems on a single "lot" have a combined flow greater than 7,500 gallons per day.

DEEP Subsurface Sewage Disposal Program

Community systems.

DEEP Subsurface Sewage Disposal Program

Any system utilizing alternative treatment, regardless of size.

DEEP Subsurface Sewage Disposal Program
Systems regulated by the Connecticut Department of Public Health (DPH)

Conventional system with design flow less than 2,000 gallons per day.

Local health department in the town the site is located

Conventional system with design flow greater than 2,000 gallons per day but less than 7,500 gallons per day.

DPH Sewage Program

Additional Information:

General Permit to Discharge from Subsurface Sewage Disposal Systems Serving Existing Facilities

Individual Permit Application for a Subsurface Sewage Disposal System

Guidance Document for Design of Large-Scale On-Site Wastewater Renovation Systems

Department of Public Health (DPH) - On Site Sewage Disposal 

Environmental Protection Agency (EPA) - Septic System Information (includes information for individual homeowners)

Best Management Practices for Non-Domestic Wastewaters Associated with Secondary, Trade and Technical School Facilities

Content Last Updated June 5, 2024