Industrial Discharge Control Program

To return clean water to the environment means more than treating wastewater from households. We pay special attention to wastewater from industrial and commercial users.

WSSC Water has been regulating non-domestic wastewater discharges to its sanitary sewer system since 1925. Now known as the Industrial Discharge Control (IDC) program, this pretreatment program was approved by the U.S. Environmental Protection Agency (EPA) in 1983 and has since been recognized nationally by EPA as an "Outstanding Pretreatment Program."

The objectives of the IDC program are to:

• Prevent the introduction of pollutants that interfere with operation of WSSC Water's water resource recovery facilities.
• Prevent the introduction of pollutants that pass through or are incompatible with WSSC Water's water resource recovery facilities.
• Improve opportunities to recycle and reclaim municipal and industrial wastewater and sludge.
• Protect infrastructure by reducing corrosion, blockages and physical damage to the sanitary sewer collection system, including pumps and associated equipment.
• Protect the health and safety of the public and WSSC Water's workers.
• Enforce pretreatment standards for Industrial Users to meet Clean Water Act requirements and ensures compliance with the WSSC Plumbing and Fuel Gas Code. 

The program meets its objectives by evaluating Industrial Users for compliance with the WSSC Plumbing and Fuel Gas Code; issuing permits for Significant Industrial Users (SIUs), conducting wastewater monitoring and comprehensive facility inspections and issuing permits to waste haulers operating within WSSC’s jurisdiction. For more information about WSSC Water’s Waste Hauler program, please visit the Waste Hauler Program page.

Industrial User Permitting Program

An Industrial User is defined as any place of business, endeavor, arts, trade or commerce, whether public or private, commercial or charitable, that uses water in a product, process, or any manner that generates wastewater, which is a source of indirect discharge. All Industrial Users located within WSSC Water's jurisdiction must comply with Section 8 of the WSSC Plumbing and Fuel Gas Code, Industrial Waste Regulations. 

WSSC Water routinely evaluates Industrial Users for compliance with the WSSC Plumbing and Fuel Gas Code and to determine whether a WSSC Water Discharge Authorization Permit (DAP) is required. This review helps ensure that industrial discharges do not harm the sanitary sewer system or its workers, interfere with treatment processes, or impact water quality. New and existing businesses that are uncertain of their status may submit an Industrial Wastewater Survey (IWS), which WSSC Water reviews to determine regulatory applicability and Code compliance.

Through its pretreatment program, WSSC Water regulates a range of Industrial Users. Permitted users may include Significant Industrial Users (SIUs), certain zero dischargers, and temporary dischargers of metered wastewater. All SIUs are required to obtain a DAP by submitting a DAP application, which are issued for a four-year term.

WSSC Water has compiled the following permitting guidelines and resources to assist businesses operating within its jurisdiction:

• Discharge Authorization Permit Application (PDF 2.44 MB)
• Industrial and Special Waste Regulations (PDF 339 KB)
• Industrial Discharge Control Program Permitting FAQs (PDF 317 KB)
• Industrial User Facility Construction or Modification Guidelines (PDF 240 KB)
• Industrial Wastewater Survey (PDF 323 KB)
• Temporary Discharge Authorization Permit Guidelines for Hydro-Demolition Dischargers (PDF 180 KB)

Industrial User permit fees for Fiscal Year (FY) 2026 (July 1, 2025 – June 30, 2026) are as follows:

• New permit: $10,715/4 years
• Permit renewal: $5,255/4 years
• Initial zero-discharge CIU permit: $4,065/4 years
• Reissued zero-discharge CIU permit: $2,710/4 years
• Temporary discharge permit (Non-SIU): $10,715 (effective for length of project)

IDC Annual Program Fee

SIUs with active DAPs will share part of the cost of WSSC Water's administration of the Industrial User pretreatment program. Annual program fees are based on the volume and characteristics of the non-domestic wastewater discharged, as well as the level of oversight required to ensure compliance with WSSC Water and federal standards.

The FY2026 IDC annual program fees are as follows:

Special Note to Landlords

Property owners with tenants that discharge non-domestic wastewater to the WSSC Water sanitary sewer system may see an annual program fee on their bill. Upon written request from the property owner, WSSC Water can provide a breakdown of tenant names and associated fees. 

Dental Office Dental Amalgam Reporting Requirements

EPA has established Dental Effluent Guidelines requiring dental offices to operate amalgam separators to prevent mercury-containing dental amalgam from entering the sanitary sewer. Both existing and new dental offices are required to submit a one-time compliance report to their pretreatment Control Authority.

WSSC Water serves as the delegated Control Authority for dentist offices within its service area. Dental offices that have not yet submitted a form, have changed their practices, or are new to the WSSC Water service area must complete the WSSC Water One-Time Dental Amalgam Compliance Report (PDF 996 KB) and mail the original ink signature copy to the WSSC Water address provided on the final page of the report.

Inspections, Monitoring and Enforcement

The IDC program regulates approximately 40 SIUs, which are inspected and monitored at least annually to verify compliance with federal and local discharge limitations.

Violations of applicable discharge limits or permit conditions may result in enforcement actions, consistent with the program's Enforcement Response Plan (PDF 636 KB).

Public Notice of the Significant Industrial User Pollution Violation(s)

In accordance with Title 40, Part 403 of the Code of Federal Regulations (CFR): General Pretreatment Regulations for Existing and New Sources of Pollution, WSSC Water administers the IDC program to regulate the discharge of pollutants to the sanitary sewer system in Montgomery and Prince George's counties. The program’s purpose is to protect the environment, to prevent interference of wastewater operations, to prevent the pass-through of pollutants into local waterways and to ensure the quality of treatment plant sludge.

The following Industrial Users were found to be in Significant Noncompliance (SNC), as defined in 40 CFR 403.8(f)(2)(viii), with EPA's National Pretreatment Standards and/or applicable local limits:

Industrial User Pollution Violation(s)