EPA Effluent Limitations Guidelines and Standards for the Dental Category (Amalgam Separator Rule)

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By Chris Wall, Medentex HWI member

The Environmental Protection Agency (EPA) released its final rule for technology-based pre-treatment standards under the Clean Water Act. This new rule, coined the "EPA Amalgam Separator Rule", will reduce mercury discharges from dental offices discharging into the municipal sewage system where the wastewater is treated at the Publicly Owned Treatment Works (POTW). ” 

Although mercury has been well documented as a persistent and bio-accumulative pollutant, until now mercury from U.S. dental offices have not been regulated. Mercury and its ecological effects are a global concern, the American dental industry is responsible for 40% of mercury found in American public waterways. This was documented after a voluntary mercury reduction program lasting 6 years failed. As a result the EPA, the American Dental Association (ADA) and other authorities decided to regulate dental amalgam.

The EPA Amalgam Separator Rule became effective on July 14, 2017 with a three year transition period for compliance (July 14, 2020). From July 14, 2017, most dental offices that discharge wastewater to POTWs across the United States must install an amalgam separator as well as follow best management practices (BMP) recommended by the ADA. That is the essence of the new EPA Amalgam Separator Rule, also known as Effluent Limitations Guidelines and Standards for the Dental Category. Dental offices located in a previously regulated areas are also subject to the EPA rule and should ensure they are still compliant.


According to the EPA, dental clinics are the main source of mercury discharges to POTWs. The EPA estimates that about 103,000 dental offices use or remove amalgam in the United States. Almost all of them send their wastewater to POTWs. The EPA has estimated that dentists discharge approximately 5.1 tons of mercury each year to POTWs.


The Amalgam Separator Rule requires dental offices to use amalgam separators and follow two BMPs recommended by the ADA:

  1. Use evacuation cleaners with pH between 6 and 8.
  2. No amalgam waste discharged to POTWs.


The Amalgam Separator Rule is applicable to all Dental Dischargers. A Dental Discharger is defined as a facility where the practice of dentistry is performed, including, but not limited to, institutions, permanent or temporary offices, clinics, home offices, and facilities owned and operated by Federal, state or local governments, that discharges wastewater to a POTW.

The Amalgam Separator Rule does not apply to the following Dental Dischargers:

  1. To Dental Dischargers that exclusively practice one or more of the following dental specialties: oral pathology, oral and maxillofacial radiology, oral and maxillofacial surgery, orthodontics, periodontics, or prosthodontics.
  2. To wastewater discharges from a mobile unit operated by a Dental Discharger.
  3. To Dental Dischargers that do not discharge any amalgam process wastewater to a POTW, such as dental facilities that discharge amalgam process wastewater into a septic system.

All new dental offices must comply with the EPA rule on amalgam waste effective July 14, 2017.

Pretreatment amalgam solids

The Amalgam Separator Rule requires all applicable Dental Dischargers to remove dental amalgam solids from ALL amalgam process wastewater by installation, operation, and maintenance of one or more amalgam separators, or amalgam removal device(s) that meet the following requirements.

  • Achieve at least a 95% removal efficiency.
  • Sized to accommodate the maximum discharge rate of amalgam process wastewater.
  • Inspected in accordance with the manufacturer’s operating manual to ensure proper operation and maintenance.
  • Retaining units (containers) replaced in accordance with the manufacturer’s schedule and operating manual.

Pretreatment BMPs

The Amalgam Separator Rule requires all applicable Dental Dischargers to implement the following two Best Management Practices (BMPs).

  1. Waste amalgam including, but not limited to, dental amalgam from chair-side traps, screens, vacuum pump filters, dental tools, cuspidors, or collection devices, must not be discharged to a POTW.
  2. Dental unit water lines, chair-side traps, and vacuum lines that discharge amalgam process wastewater to a POTW must not be cleaned with oxidizing or acidic cleaners, including but not limited to bleach, chlorine, iodine and peroxide that have a pH lower than 6 or greater than 8.

Reporting and recordkeeping

The Amalgam Separator Rule requires:

  1. Existing Dental Dischargers to provide a one-time Compliance Report to their Control Authority no later than 3 years and 90 days from the rule Effective Date, or 90 days from transfer of ownership.
  2. New sources to provide a one-time Compliance Report to their Control Authority no later than 90 days following the introduction of wastewater into a POTW.
  3. To maintain for inspection, in either physical or electronic form, for a minimum of 3 years, the following documentation.
    • Date, person(s) conducting the amalgam separator inspection.
    • Amalgam retaining container (or equivalent) replacement, including the date.
    • dates that collected dental amalgam is sent for proper disposal in accordance with 40 CFR 261.5(g)(3), and the name of the permitted or licensed treatment, storage or disposal facility receiving the amalgam retaining containers.
    • Repair or replacement of an amalgam separator or equivalent device, including the date, person(s) making the repair or replacement, and a description of the repair or replacement (including make and model).

Require standards for the type of amalgam separator

Installation, operation, and maintenance of one or more amalgam separators that meet the following requirements:

  1. Compliant with either the American National Standards Institute (ANSI) American National Standard/American Dental Association (ADA) Specification 108 for Amalgam Separators (2009) with Technical Addendum (2011) or the International Organization for Standardization (ISO) 11143 Standard (2008) or subsequent versions so long as that version requires amalgam separators to achieve at least a 95% removal efficiency. Compliance must be assessed by an accredited testing laboratory under ANSI's accreditation program for product certification or a testing laboratory that is a signatory to the International Laboratory Accreditation Cooperation's Mutual Recognition Arrangement. The testing laboratory's scope of accreditation must include ANSI/ADA 108-2009 or ISO 11143.
  2. The amalgam separator(s) must be sized to accommodate the maximum discharge rate of amalgam process wastewater.

What is Dental Amalgam?

Dental amalgam consists of Copper, Silver, Zinc and Tin as contains up to 50% mercury. Mercury is the only common metal that is liquid at room temperature and is one of most toxic elements on Earth. Mercury vapor is odorless, tasteless and colorless and in its liquid form there is limited absorption through skin.

Ecological Effects of Mercury Exposure

Scientists have found alarming levels of mercury accumulation in a wide variety of wildlife species, causing reproductive and neurological problems. Birds and mammals that eat fish have more exposures to methylmercury than other animals in water ecosystems. Predators, including humans,that eat the fish, birds and mammals are also at risk.

Is the amalgam collected in the separator considered a hazardous waste?

The amalgam collected in a separator is likely to be a hazardous waste under the Resource Conservation and Recovery Act (RCRA) due to the mercury and silver content of the amalgam. Dental offices producing less than 100 kg of hazardous waste per month and less than 1 kg of acute hazardous waste per month are considered Very Small Quantity Generators (VSQGs) and are exempt from most RCRA requirements for the disposal of their hazardous waste (note that VSQGs were formerly called conditionally exempt small quantity generators (CESQGs), but were renamed in November 2016). The EPA generally does not expect dental offices collecting amalgam waste to be above the VSQG threshold.

State and local requirements

The EPA rule is a floor (i.e. a minimum requirement), not a ceiling, for regulating discharges of dental office wastewater to POTWs. There may be additional requirements under state or local laws that exceed those in EPA’s new rule.

Estimated costs for dental offices

The EPA has researched the estimated costs for dental offices ranging from small 1-2 chair to very large 15 chairs dental offices with the new rule. Their estimate is based on values in 2016 and with government applied discounts, therefore the actual costs will be higher than those stated in the graph below. Realistically, year one cost will range from $80m to $100m and subsequent years from $50m to $60m allowing for non-discounted separators, replacement parts, etc. and 2017 prices. The graph below shows these costs as market potential due to the services and products required for compliance with the new rule. The EPA estimates there will be 1% growth in dental offices year-on-year in the US.

Annual Market Potential Chart

Useful Links:

  1. EPA Final Amalgam Separator Rule: Effluent Limitations Guidelines and Standards for the Dental Category
  2. EPA Web site: Dental Effluent Limitations
  3. Proposed rule: Effluent Limitations Guidelines and Standards for the Dental Category
  4. Docket No. EPA-HQ-OW-2014-0693: Government Printing Office's FDsys website
  5. Office of Management and Budget: Rule - Reginfo.gov


Dental amalgam discharged to POTWs has contributed to a significant portion of mercury in our waterways. By regulating dental amalgam management, this new rule is anticipated to reduce that quantity more effectively than previous volunteer efforts. Dental Dischargers have until June 14, 2020 to come fully into compliance.

About the writer

Chris Wall is General Manager North America for medentex LLC (the word medentex is not capitalized) and has nearly 30 years of experience in the dental and medical waste industry and was originally from London England but now lives in New Jersey.

About the Healthcare Waste Institute

The Healthcare Waste Institute is made of members representing transporters, suppliers, processors, and disposal facilities. Our mission is to facilitate responsible healthcare waste management among those handling infectious and hazardous waste arising from the healthcare industry.

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