CONCORD, N.H. – The state Supreme Court says it’s illegal for Manchester to put fluoride in the water it pipes to customers in surrounding towns.

The court gave the city until June 30, 2005, to stop fluoridating the municipal water supply, unless the Legislature amends the law before then or residents in the towns approve.

After Manchester voters approved, the city began adding fluoride, a substance that reduces tooth decay, in the municipal water supply in 2000. However, the Manchester system also provides drinking water to Auburn, Bedford, Goffstown, Hooksett, Derry and Londonderry, where residents did not vote on the fluoride question.

The court ruled the law requires all people using the water to vote on whether they want it fluoridated.

Manchester had argued the law required a vote only by Manchester residents.

The decision raises questions for water utilities in other cities, such as Dover, Portsmouth and Laconia, that sell fluoridated water to surrounding communities.

Attorney Jed Callen, who challenged the fluoridation, said legislators will face constitutional problems if they try to amend the law so people in outlying towns don’t get to vote on fluoridation.

“I think they recognize that fluoride is a serious and controversial matter and people have a right to determine if they want to be dosed with a drug or not,” said Callen.

He said very few children don’t receive proper dental care and don’t use fluoride toothpaste, so it doesn’t make sense to give an entire population fluoride to reach them. It would be cheaper and more effective, he said, to provide dental services through the schools.

Meanwhile, in other cities, Jeffrey Kellett, chairman of Laconia’s water commission, said Laconia will review the court decision with the city’s legal counsel before responding.

“Up until today, it’s been in the court’s hands. We haven’t talked about what direction were going to go in,” Kellett said.

Dover Director of Community Services Peter Lavoie said his city provides fluoridated water to only a “minute” number of people in other towns to fewer than 10 customers in Madbury and 35 or 40 in Rollinsford.

“We have a few people on the border. It isn’t like Manchester, which is feeding a whole other community,” Lavoie said.