Dentists across the country could be taking part in a massive overhaul of their filling procedures in the very near future.

According to the National Journal, the Environmental Protection Agency (EPA) released a proposal on Thursday, Sept. 25 to significantly reduce the amount of mercury that enters the country’s water supplies.

The main target of the proposal? Dentist’s offices — as routine dental procedures like fillings are largely responsible for mercury entering the environment.

When an old dental filling is removed, or when a dentist has more of the filling material than is needed, the mercury is often rinsed down the drain; from there, it enters the surrounding ecosystem’s water. As a result, the EPA reports that more than half of the mercury detected in public water treatment plants comes from discarded dental fillings, according to the National Journal.

“Mercury is a persistent and bioaccumulative pollutant with well-documented effects on human health,” the EPA said in a statement. “When in water, certain microorganisms can change mercury into methylmercury, a highly toxic form that builds up in fish, shellfish and animals that eat fish.”

To solve this problem, the EPA wants dentist’s offices across the U.S. to adopt new systems that limit how much mercury and other heavy metals end up in the water supply, the National Journal reports.

A device called an amalgam separator, which can be purchased for around $700, filters drain water and removes microscopic mercury particles, according to an article on TheBlaze.com. However, if a dentist doesn’t want to purchase the device, he or she can follow American Dental Association guidelines for reducing mercury waste instead.

Ultimately, the EPA estimates its proposal could remove as many as 8.8 tons of mercury and other heavy metals from public water treatment facilities each year.