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Industrial Discharge Control FAQs

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General Information

It is the pretreatment of non-domestic wastewater - wastewater from industry or commercial enterprises rather than homes - that is discharged to WSSC Water's sanitary sewer system. The program aims to prevent the introduction of pollutants that interfere with the operation of our water resource recovery facilities or pass through our treatment facilities


Pretreatment is the reduction, elimination, or alteration of pollutants in wastewater to a less harmful state before discharging the wastewater to a sanitary sewer system.

It is a program mandated by the Environmental Protection Agency that requires WSSC Water to regulate industrial discharges to our wastewater collection system, thereby reducing the amount of pollutants released into the environment by WSSC Water's treatment plants.

The Clean Water Act established the responsibility of federal, state, and local government to implement National Pretreatment Standards in order to control pollutants from non-domestic sources that discharge to a Publicly Owned Treatment Works. WSSC Water operates six water resource recovery facilities that treat wastewater from domestic and industrial sources. These WRRFs in turn discharge treated wastewater to the environment. Each of WSSC Water's WRRFs hold permits issued by the Maryland Department of the Environment. These permits regulate WSSC Water's WRRFs effluent discharges to state waterways. Each permit contains requirements to implement a pretreatment program to prevent pollution of the waterways.

Industrial Users

All industrial users located within WSSC Water's jurisdiction must comply with our Industrial Waste Regulations. However, industrial users that perform processes deemed "categorical" by the EPA and/or significant by WSSC Water must comply with additional requirements.

The term Significant Industrial User as defined by the EPA means: (1) All industrial users subject to Categorical Pretreatment Standards under 40 CFR 403.6 and 40 CFR chapter I, subchapter N; and (2) Any other industrial user that: discharges an average of 25,000 gallons per day or more of process wastewater; contributes a process wastestream which makes up 5 percent or more of the average dry weather hydraulic or organic capacity of the treatment plant; or is designated as a SIU by WSSC Water on the basis that the industrial user has a reasonable potential for adversely affecting the operation of WSSC Water's wastewater treatment plants.

Potential SIUs under construction should submit a WSSC Water Discharge Authorization Permit Application at least 90 days before discharging to WSSC Water's sanitary sewer. Existing SIUs should apply as soon as possible.

To obtain a WSSC Water Discharge Authorization Permit you must complete a WSSC Water Industrial User Survey and submit it to this office. If your industry meets the definition of a Significant Industrial User, you do not have to fill out the Industrial User Survey; however, you must complete a WSSC Water Discharge Authorization Permit Application and submit it to this office in the timeframe mentioned above.

If an industrial user does not comply with pretreatment program requirements, it will be subject to enforcement action in accordance with the guidelines established in WSSC Water's Enforcement Response Plan.

Last Modified: June 14, 2023, 9:43 am EDT