In June 14, 2017, U.S. EPA finalized technology-based pretreatment standards under the Clean Water Act to reduce discharges of mercury and other metals from dental offices into municipal sewage treatment plants known as publicly owned treatment works (POTWs). Dental offices, which discharge mercury and other metals present in amalgam used for fillings, are a significant source of mercury discharges to POTWs; POTWs subsequently release these metals into the environment. The federal rule at 40 CFR 441 requires dental offices comply with requirements based on the American Dental Association’s recommended practices, including the use of amalgam separators. You can find this rule and supporting documents at the Missouri Dental Association.

Dental Facilities Subject to the Rule

Your dental facility may be subject to the EPA Dental Amalgam Rule. In general, the rule places dental facilities in two categories, new or existing dental facilities that remove and replace dental amalgam. The requirements for these two facilities are as follows:

  •  A new dental facility that commenced operation on or after July 14, 2017 essentially must 1) have an amalgam separator installed from the onset of seeing patients, and 2) within 90 days of the first discharge to the POTW submit a one-time compliance report (OTCR).
  • Existing dental facilities that discharge amalgam process wastewater to a POTW prior to July 14, 2017 must 1) submit an OTCR before Oct. 12, 2020, and 2) have a compliant amalgam separator or equivalent device installed by July 17, 2020. If these existing facilities have an equivalent device, they must install a compliant separator by July 14, 2027, or once the equivalent device breaks down.         

More details on the basic requirements of EPA Dental Amalgam Rule are found in the Dental Amalgam Rule Facts section of the Missouri Dental Association.

Who is your Control Authority: POTW or MoDNR?

The Missouri Department of Natural Resources implemented EPA’s Dental Amalgam Rule by using the new rule as guidelines and informed their regulated community, municipalities with POTW state-approved pretreatment programs, how to best interpret the new rule. Many POTWs with state-approved pretreatment program responsibilities have implemented an outreach effort to contact dental facilities regarding the need to comply with the rule. 

For those POTWs that have state-approved pretreatment programs, the responsibility for seeking compliance with the dental amalgam rule rests with these local POTW authorities. Any subsequent enforcement action related to noncompliance with the rule also rests with POTW authorities with state-approved pretreatment programs. To submit an OTCR, contact the local POTW authority or “control authority” for an OTCR form, or see “Where do I get a one-time compliance report?” in the Dental Amalgam Rule Facts section of the Missouri Dental Associations web link. To determine whether your municipality is the control authority for your dental amalgam process wastewater discharge, please see “Who is your control authority?” within the Missouri Dental Association website.

For POTWs without state-approved pretreatment program responsibilities, the department acts as the control authority. For assistance in determining whether the department is your control authority, please see “Who is the control authority for dental dischargers outside of an approved program?” For those dental facilities that discharge to a POTW without a state-approved program, the department’s OTCR form is available. 

For More Information

For more regulatory information on the Dental Amalgam Rule and department implementation, visit the Missouri Dental Association website. If you need compliance assistance with the EPA Dental Amalgam Rule, please contact your local POTW control authority or the department's Industrial Pretreatment Coordinator.