CONCORD — The House yesterday approved a process that would allow multi-town water districts to determine whether fluoride should be added to the water supply.

The bill stems from a lawsuit filed by people in communities who receive their water from the Manchester Water Works and were not able to vote on whether fluoride should be added to the water.

The bill, SB 449, sets up a referendum on primary election day, Sept. 14, for Manchester and the communities its water department serves to vote on the question, “Shall fluoride be used in the Manchester public water system?”

The Secretary of State’s Office will tabulate the results and forward them to the Manchester city clerk. The expenses for printing the special ballots will be borne by the water department.

Under the bill, a municipality that has a vote on the issue has to have more than 100 connections. There was an unsuccessful attempt to remove the required 100 connections and allow any town with connections to vote on the issue.

Rep. Barbara Hagan, R-Manchester, said: “The issue needs to be debated and decided by each voter. You cannot deny one voter the right to cast a ballot on this important issue regardless of how you feel on the issue of fluoride.”

She said people living in Auburn send their children to high school in Manchester and others work in the city even if they drink well water at home.

Rep. Peter Schmidt, D-Dover, said the 100-connection limit was intended to exclude multi-town water systems with few connections in other communities so they would not have to go through the referendum process.

Jesse Osborne, D-Concord, said 11 household in Bow are on Concord’s water system. If there were no connection requirement, she said, “The entire town of Bow would vote on the question of whether Concord should have fluoridation.”

Under the bill approved yesterday, 10 percent of the registered voters in a municipality can petition their selectmen to put a referendum on whether fluoride should be used in the water system on the annual meeting or election ballot.

The majority of all voters in the municipalities that belong to the water district would have to vote to begin using fluoride in the system or to stop using fluoride. Single communities could not decide whether fluoride would be in their water.

A referendum could only be held once every three years.