Guide to the Dental Amalgam Rule

The Environmental Protection Agency (EPA) estimates that 50 percent of mercury entering public wastewater treatment facilities comes from amalgam discharged by dental practices. To reduce this toxic metal in treatment facilities, the EPA established the Dental Amalgam Rule.
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Pollutants of Concern

Dental amalgam is a common filling material made mostly of mercury and a mixture of other heavy metals: silver, tin, copper, and zinc. When introduced into the environment, mercury from amalgam has a toxic effect on aquatic organisms. Portland's wastewater treatment facility is not designed to remove mercury, so any mercury discharged from dental practices has the potential to enter the Willamette and Columbia rivers. Controlling amalgam discharges from dental practices protects public health and the environment.

Who Should Participate

The EPA requires the City to implement the rule for dental practices that discharge wastewater to a Portland-owned wastewater treatment facility.

Dental practices that report to the City of Portland:

  • Are directly connected to the City’s sanitary sewer system.
  • Are connected to a surrounding city or district that sends a portion of their sewer to a Portland treatment facility. These include Clackamas, Gresham, Dunthrope-Riverdale, Lake Oswego, Milwaukie, Tualatin, Hillsboro, and West Hills Service District. If you receive a notice from Portland, your practice has been identified by a sewer mapping database as a discharger to the City of Portland.

Dental Practices that do not report to the City of Portland:

  • Send wastewater to another city or district’s treatment facility.
  • Are connected to a septic tank, cesspool, or holding tank.

Dental Best Management Practices (BMPs)

  • Install, operate, and maintain an approved amalgam separator.
  • Inspect the amalgam separator(s), at a minimum, once per month to ensure proper operation and confirm that there is no bypass of the separator.
  • Repair or replace defective amalgam removal equipment/components in accordance with the manufacturer’s specifications.
  • Maintain the amalgam separator(s) regularly by replacing retaining cartridges, separator canisters, filters, and/or other treatment units annually, or whenever the unit reaches the manufacturer’s design capacity, whichever comes first.
  • Do not use oxidizing or acidic cleaners to flush dental unit water lines.
  • Collect scrap amalgam from chair-side traps, screens, vacuum pump filters, dental tools, and/or other collection devices for off-site disposal. Scrap amalgam must not be flushed down the drain.
  • Maintain logs documenting amalgam separator maintenance activities and waste amalgam disposal.

Is Your Practice Required to Implement these BMPs?

Dental practices required to implement BMPs:

  • All dental practices that place or remove amalgam on a regular basis, such as offices, large dental institutions, schools, and clinics.

Dental practices exempt from BMPs:

  • Dental specialty practices like oral pathology, oral and maxillofacial radiology or surgery, orthodontics, periodontics, or prosthodontics.
  • Mobile units.
  • Dental practices that do not place or remove amalgam except in limited, emergency, unplanned, or unanticipated circumstances.

All Practices Must Apply for Compliance Certification

All dental practices that discharge wastewater to a Portland-owned wastewater treatment facility must verify that they are in compliance with Environmental Services rules by applying for compliance certification.

Apply for Dental Practice Compliance Certification

What to Expect After Applying for Certification

Applicable dental practices will be issued a discharge authorization from the City. The authorization documents the required BMPs. The City will periodically conduct inspections of dental practices to ensure BMPs are in place and being followed. In addition to a physical inspection of amalgam capturing devices, the following records will be reviewed:

  • Amalgam separator maintenance and waste management log.   
  • Receipts or manifests that document amalgam waste disposal destination.

Dental practices that claim the exemption on the initial certification report will receive a letter acknowledging their exemption status. No further actions are required for these facilities unless the practice changes and becomes covered by the Dental Amalgam Rule.

Annual Reporting

If your dental practice is required to implement the BMPs, your practice must also submit Annual Certification Reports.

File an Annual Certification Report

Additional Resources