Voters have decided to stop fluoridating water in the Kennebunk, Kennebunkport and Wells Water District.

Residents of seven towns in the district voted to stop treating drinking water with fluoride, 13,385 votes to 6,918 votes.

Kennebunk, Kennebunkport, Wells, Ogunquit, Arundel and parts of Biddeford and York get their water from the district. Fluoride is commonly added to public water supplies across the country as a way to combat tooth decay.

“The Water District is pleased with the outcome of the fluoride referendum,” said district superintendent Norm Labbe, in a written statement.

“It’s evident that the voting public is now more informed about the subject than they were back in 2002, when fluoridation was voted in. The water district thanks the Campaign to Reconsider Water Fluoridation volunteers and in particular the voters for their knowledgeable decision to cease the addition of fluoride to out water,” Labbe added.

“We look forward to staying true to our mission of providing the highest quality of water at the lowest reasonable cost.”

A small group of residents under the banner of the Campaign to Reconsider Fluoride pushed the issue to a ballot referendum, concerned that the practice amounts to mass-medicating and over-fluoridation.

The water district started adding fluoride to water in 2004 as part of a 2002 referendum. Janice Hanson, a Kennebunk resident and chairman of the Campaign, has said fluoride is an unnecessary toxin that should not be ingested.

Health experts said that water fluoridation is a beneficial public health measure to prevent tooth decay, especially in children.

Joseph R. Kenneally, a dentist from Kennebunk, in an October Portland Press Herald op-ed said the U.S. Centers for Disease Control, as well as numerous other professional medical associations support fluoridation, and estimated depriving district residents access to the treatment would lead to a resurgence of tooth decay.

The water district board and its superintendent “are not doctors or public health experts, and are not there to make judgment about the safety and efficacy of community water fluoridation,” Kenneally said in his editorial.

Correction: This story was updated at 9:57 a.m. on Thursday, November 10, 2016 to correct the final vote tally.