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Metropolitan Water Reclamation District of Greater Chicago

Frequently Asked Questions for Control Authorities on the Dental Rule (40 CFR Part 441)

The subject rule, also known as the Dental Amalgam Rule (40 CFR 441), was signed by USEPA on December 15, 2016, and published in the Federal Register on June 14, 2017. The purpose of the rule is to set a uniform national standard that will greatly reduce the discharge of mercury to POTWs and the environment. In May 2018, the USEPA published below FAQ for POTWs on the Dental Rule. 

  1. Does the dental office category rule apply to dental facilities that discharge to publicly owned treatment works (POTWs) (e.g., municipal sewage system) that have a dental amalgam reduction program? Yes. The federal rule applies to dental dischargers irrespective of any state or local dental amalgam reduction program.
  2. Is a dental discharger considered an “industrial user”? Yes. An “industrial user” is a nondomestic source of indirect discharge into a POTW. Dental dischargers are therefore considered industrial users under the general pretreatment regulations in 40 CFR part 403; see: This rule does not alter that status. However, this rule established that dental dischargers are not significant industrial users (SIUs) or categorical industrial users (CIUs) as defined in 40 CFR part 403 unless designated as such by the control authority.
  3. Are control authorities required to identify all dental dischargers? Because dental dischargers are industrial users as explained in question two, the requirements in 40 CFR §403 and §122, which pertain to control authority identification and oversight of all industrial users, continue to apply. Because dental dischargers are generally neither SIUs nor CIUs per 40 CFR §441.10(b), they are not required, under 40 CFR §403, to be individually identified in the POTW’s annual report or National Pollutant Discharge Elimination System (NPDES) permit application, unless otherwise required under state or local authorities.
  4. As a control authority, what are my oversight and enforcement responsibilities regarding dental dischargers? As noted in section VI.D.4 of the Preamble to this rule, “Control Authorities have discretion under the final rule to determine the appropriate manner of oversight, compliance assistance, and enforcement.” (82 FR 27164). However, while dental dischargers are not CIUs or SIUs, they continue to be industrial users (IUs) – defined broadly at 40 CFR §403.3 as a “source of Indirect Discharge.” 40 CFR §403.8(f) directs POTWs to establish procedures and standards to identify all IUs, including dental dischargers, to ensure compliance with the general and specific prohibitions in order to protect against pass through and interference. Control authorities, however, have discretion and flexibility on what those requirements should be for dental dischargers. As a POTW’s procedures are tailored to the capacity and capability of each POTW, as well as the NPDES permit requirements for the individual receiving water body, they will be different for each control authority. Refer to your program’s procedures and NPDES permit conditions to understand your requirements as they relate to industrial users. If necessary, control authorities have the option to modify their program to adapt their otherwise applicable procedures to dental dischargers. In some circumstances, this may be considered a substantial modification, which has special requirements described in 40 CFR §403.18. Control 2 authorities may work with their approval authority for assistance with questions on handling specific oversight, enforcement or program modification questions.
  5. What are the recordkeeping requirements for the dental office category rule for a control authority? The rule does not impose additional recordkeeping requirements on a control authority. See the recordkeeping requirements for a control authority found in 40 CFR §403.12(o).
  6. Does a dental discharger that places or removes amalgam and submitted a one-time compliance report need to submit another one-time compliance report if there are changes to the information provided on the report (e.g., I replace my amalgam separator or change the total number of chairs in my facility)? No. If, however, a dental discharger transfers ownership of the facility, the new owner must submit a new one-time compliance report. In addition, if a dental discharger submits a one-time compliance report under 40 CFR §441.50(a)(3)(i) certifying that the dental discharger does not place or remove dental amalgam except in limited circumstances but the dental discharger changes the practice such that the certification is no longer accurate, a new one-time compliance report should be submitted that includes the information required for dental dischargers subject to the standards of Part 441 (see 40 CFR §441.50(a)(3)(ii)).
  7. Can control authorities modify the language in the sample one-time compliance report that EPA posted? Yes. The sample form for the one-time compliance report developed by EPA contains the minimum information that dental facilities must submit in a one-time compliance report to comply with §441.50. Control authorities may request additional information on their one-time compliance report in accordance with the provisions of their pretreatment program’s legal authority, or in accordance with any related state or local laws. EPA recommends that control authorities cite the authority under which they are requesting this additional information, should they choose to do so. A sample one-time compliance report is available for download on EPA’s website here: 
  8. Does the 2015 NPDES Electronic Reporting Rule (40 CFR Part 127) require dentists to electronically submit their one-time compliance reports? No. The 2015 NPDES Electronic Reporting Rule (“NPDES eRule”) does not require electronic submission of the one-time compliance report because it is not listed in Table 1 of Appendix A of the NPDES eRule (40 CFR §127).
  9. Can a control authority set up an electronic reporting system to collect the one-time compliance reports? The dental office category rule does not preclude control authorities from collecting their reports electronically. Note: If a control authority establishes an electronic reporting system, it must be CROMERR-compliant (Cross-Media Electronic Reporting Rule, 40 CFR §3). 
  10. Does the dental office category rule apply to septage haulers who service the septic tanks of dental facilities? No. The dental office category rule applies only to dental dischargers – i.e. a facility where the practice of dentistry is performed that discharges wastewater to publicly owned treatment works (40 CFFR 441.20(e)). It does not apply to dental discharges to septic systems. Note: dental discharges to septic systems would be subject to regulation under the Safe Drinking Water Act Underground Injection Control Program, which may be implemented by EPA or the State depending on whether the State has primary enforcement responsibility. Other state and local regulations regarding the disposal of nondomestic wastewater to septic systems may also apply. Also note that control authorities may impose controls on the receipt of hauled nondomestic septage under federal Clean Water Act authorities.
  11. There is a dental facility that collects all amalgam process wastewater in a wastewater retaining tank, which is then pumped out of the tank and transferred to a privately owned wastewater treatment facility (a Centralized Waste Treatment, or CWT, facility as defined in 40 CFR Part 437). The CWT does not discharge the dental amalgam process wastewater to a POTW. Are these dentists subject to the rule and thereby required to submit a one-time compliance report? No. See §441.10(e). Dental facilities that do not discharge amalgam process wastewater to a POTW are not subject to this rule. As EPA noted in the preamble to the final rule, “[d]ental offices using wastewater  retention tanks must ensure that all amalgam process wastewater is collected by the wastewater retention tanks. Any uncollected amalgam process wastewater that is discharged to the POTW is subject to this rule.” 82 FR 27160, footnote 4. 
  12. Are there any requirements in the dental office rule that apply to POTWs that discharge to a water body listed as impaired on the State’s CWA 303(d) list due to mercury? No. Discharge limits for a direct discharger, such as a POTW, are established in the NPDES permit for the facility by the NPDES permitting authority. These requirements are separate from the pretreatment requirements for dental dischargers established in part 441, which are self-implementing. Additionally, as dental dischargers are neither CIUs or SIUs, they do not need to be identified in the NPDES permit or application per the NPDES application requirements at 40 CFR 122.21(j)(6).
  13. What are the regulatory consequences for dental dischargers that fail to comply with Part 441? Part 441 contains Pretreatment Standards and Requirements applicable to specific industrial users of a POTW (dental dischargers). Pursuant to Section 307(d) of the Clean Water Act, a failure to comply with such applicable standards and requirements would constitute a violation of the Clean Water Act and potentially therefore subject the industrial user, in this case the dental discharger, to federal civil and criminal penalties under Section 309 of the Clean Water Act, and to civil and criminal penalties under state and local law implementing the CWA pretreatment program.

Metropolitan Water Reclamation District 2014 through 2017 User Satisfaction Survey Results

Survey Distribution

All Large Commercial-Industrial and Tax Exempt Users (over 900 Users) that were required to file a User Charge Annual Certified Statement (RD-925) were asked to complete a survey either online through, using a paper version or via telephone survey (which was new for this year). The number of responses received were as follows: 2014: 22 responses, 2015: 9 responses, 2016: 26 responses, 2017: 49 responses

Survey Format

The 2014 and 2015 surveys were comprised of 5 questions. In 2016 and 2017, a 6th question, asking respondents to rate their overall satisfaction, was added. Questions 1 and 2 asked respondents to rate their satisfaction with IWD programs and personnel based on a scale of 1 to 5, with 1 being not satisfied and 5 being very satisfied. Questions 3 and 4 asked respondents to rate the degree of difficulty in completing the District’s User Charge and Pretreatment forms and navigating the District’s website based on a scale of 1 to 5, with 1 being difficult and 5 being easy. Question 5 asked respondents to select the two most important aspects of the IWD program that need improvement.

Survey Results

The results showed that respondents were overall very satisfied with the interactions they had with the IWD staff and, in general, were satisfied with the User Charge and Pretreatment programs. The 2017 results indicated an average satisfaction with completion of the forms and navigating the District’s website. While the majority surveyed for the 2017 reporting year did not feel that anything should be improved, those that offered their suggestion felt that the forms and ordinances need improvement.


Established in 1889, the Metropolitan Water Reclamation District of Greater Chicago (MWRD) is an award-winning, special purpose government agency responsible for wastewater treatment and stormwater management in Cook County, Illinois.


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