PLAINVILLE – As expected, Town Meeting defeated a $2.3 million proposal to separate the town’s water from neighboring North Attleborough’s, which means Plainville will continue to get fluoridated water even though voters rejected it more than a year ago. The question is, what now?

Both foes and supporters of fluoridation dismissed the plan as far too expensive, and Monday’s Town Meeting reflected that by unanimously voting it down.

”This is a budget buster,” Selectman Rob Rose told residents just before the vote. ”To me this makes no sense. It’s ludicrous, it’s odious.”

But most officials argue that although too pricey, the $2.3 million plan represented the only way engineers could find to completely remove fluoride from Plainville’s water. Antifluoride activists, who argue that fluoride presents health risks, say they aren’t buying it and want officials to search harder.

”There are other solutions to this problem that have not been looked at.” Mary Gibeault told Town Meeting.

Gibeault was president of the defunct Plainville Citizens for Safe Drinking Water, the group that campaigned against fluoridation. In April she was elected to the Board of Health.

In a phone interview after the meeting, she said she has distanced herself somewhat from the issue since she was elected but believes the town should further explore filing a lawsuit against North Attleborough. During the anti-fluoridation campaign, Gibeault told voters that getting rid of fluoride should not cost Plainville anything because North Attleborough should have to pay for the water separation if it wants to continue fluoridating, a position she still maintains.

Other officials accept town counsel John Lee’s opinion that Plainville should not sue because it has no case.

”He doesn’t think it’s a winnable case, so that’s it in his opinion,” said Leland Ross Jr., chairman of the Board of Water and Sewer Commissioners.

But a new informal group of activists is lobbying for fluoride removal.

”We don’t think it’s a dead issue,” said Kathleen Fontaine, one member of the group. ”We’re just trying to get our officials to do their job. Some of the board members are pro-fluoride and their inaction is deliberate.”

Fontaine said she agrees with Gibeault that legal action against North Attleborough should receive more consideration, and she added that engineering solutions should be better explored, either by hiring another firm or by more aggressively challenging the firm that came up with the expensive plan to find a cheaper one.

But the town did try to follow the will of the voters, said Andrea Soucy, chairwoman of the Board of Selectmen, and professional engineers say the high-priced solution is the only way to guarantee that the water is 100 percent fluoride-free.

”This is the only viable solution to fulfilling the mandate of the people,” she said, adding that last year’s referendum might have gone the other way if voters knew getting rid of fluoride would cost money. ”I think that if people had known that it was going to cost them, they might have voted differently.”

About half of Plainville’s water is currently fluoride-free (except for naturally occurring fluoride) because it is treated in Plainville, Ross said. That water goes to the east side of town, he said.

By contrast, residents on South Street, next to the North Attleborough town line probably get the full dose of fluoride all the time, Ross said. Others in town, he said, get a mix — some fluoride but less than what is recommended to prevent tooth decay.

Ross said his board is required to provide safe drinking water, which it is doing by state standards, he said.

”I don’t know where we go from here,” he said.