Under the Resource Conservation and Recovery Act (RCRA), some types of hazardous waste may be disposed of to a sanitary sewer if they mix with domestic waste and are sent to a publicly owned treatment works (POTW), under what is commonly referred to as the “Domestic Sewer Exclusion”. These materials are not defined as solid wastes and, therefore, are not hazardous wastes for the purposes of RCRA compliance. For the Domestic Sewer Exclusion to apply disposal must in conformance with local, state, and federal water requirements. Materials covered by the Domestic Sewer Exclusion are “domestic sewage; and any mixture of domestic sewage and other wastes that pass through a sewer system to a publicly owned treatment works for treatment.

This photo shows an example of a floor drain, trench drain discharging to a Flammable Waste Trap / Oil Water Separator

Flammable Waste Trap / Oil Water Separator


When Congress provided for the Domestic Sewer Exclusion in RCRA, the intent was to relieve certain types of small hazardous waste generators from RCRA compliance. These types of small businesses were thought to be typically found in residential areas and may not have access to a dedicated industrial sewage line. However, depending on the volume and types of wastes, these generators may still be required to comply with other solid waste requirements before disposal.

Some key considerations regarding possible applicability of the Domestic Sewer Exclusion include:

  • The generated waste is subject to controls under the Clean Water Act, specifically pretreatment standards, including any applicable local limits imposed by the state or POTW, or nationally applicable categorical pretreatment limits.
  • The POTW must be equipped to treat the waste, and dischargers must contact the POTW to obtain instructions and conditions on the acceptability of the waste and how it should be treated before disposal.
  • The waste must pass through a sanitary sewer system to the POTW. Hazardous waste that is transported to the POTW by truck or rail is not entitled to the exclusion even if it mixes with domestic sewage. The hazardous waste must enter the sewer line at or near the point of generation.

Caltha LLP provides expert consulting support for hazardous waste generators to determine waste handling and disposal options and to develop effective waste management programs and procedures.


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