The United States Environmental Protection Agency (“EPA”) has proposed standards for pretreatment of water that goes down the drain at a dentist’s office.  The proposed rule, available here, would require dental practices to meet technology-based pretreatment standards pursuant to the Clean Water Act for discharge of dental amalgam into publicly owned treatment works (“POTWs”), that is, municipal sewage treatment systems.

Dental amalgam contains mercury and enters the waste stream when a dentist fills a patient’s cavity, or removes an old filling.  The rule would require dental offices to control the discharge of mercury and other metals by using best available technology.  One available technology is an “amalgam separator” that removes solids that go down the chair-side drain or vacuum from wastewater.  Additionally, best management practices prohibit dental offices from flushing scrap amalgam down the drain and require offices to use a cleaner that does not contain bleach for chair-side traps because bleach can solubilize any mercury and increase discharge.

The proposed rule would also seek to streamline permitting and oversight requirements due to the large number of facilities subject to these proposed standards.  While EPA classifies the amalgam separator as an affordable and readily available technology, dentists should be aware of these proposed standards and any potential impact on their practice.  The deadline for public comment is December 22, 2014.