Dental Facilities

Dental Office Category Rule

Dental facilities that discharge wastewater into the Spokane County sanitary sewer system must be in compliance with County discharge limits and Environmental Protection Agency (EPA) regulations.  The EPA put into effect the Dental Office Category Rule codified at 40 CFR Part 441 (§441) on July 14, 2017, to reduce discharges of mercury from dental offices.


Dental Discharger Requirements


  • Ensure the removal of dental amalgam solids from all amalgam process wastewater via amalgam separator(s) or equivalent device(s) that meet the standard of the rule. See §441.30(a) (1-2) for an existing source and §441.40 for a new source. 
  • Implementation of two best management practices. See §441.30(b) for an existing source and §441.40 for a new source.
    • Comply with reporting requirements – One-Time Compliance Report. See §441.50(a).
    • Existing dental dischargers must submit a One-Time Compliance Report to the Spokane County Industrial Pretreatment Program within 90 days after transfer of ownership.
  • For new dental facilities, the One-Time Compliance Report must be submitted no later than 90 days.


Compliance reports should be sent to: 

Spokane County Public Works 

Attn: Mia Suhrbier

1004 N Freya St

Spokane, WA 99202

 Please contact (509) 477-7177 if you have questions or need assistance with the compliance report.