Six months after voters chose fluoride-free water, residents still have a 50 percent chance of getting fluoridated water every time they turn on a tap.

About half of the town’s water goes through a treatment facility that Plainville shares with neighboring North Attleborough, which adds fluoride to its water. The two towns received four options for separating their water supplies from consulting engineers Tata & Howard, but many in town say none stands out as a solution.

At $175,000 and $380,000, the two lower-cost options would remove fluoride only some of the time, said James Marshall Jr., Plainville’s water and sewer superintendent. And the two more expensive alternatives, at $1.5 million and $1.8 million, are too high for officials and for antifluoride activists.

”I wouldn’t spend a penny on any of that. None of it is viable,” said Mary Gibeault, a fluoride opponent who is president of Plainville Citizens for Safe Drinking Water. ”None of those options were what we looked for.”

Gibeault was part of the effort to collect more than 500 signatures – the required 10 percent of registered voters – to secure a spot on the April ballot for the antifluoride effort.

A year before, Plainville’s Board of Health voted in favor of fluoridating town water. When voters reversed that decision at the polls, many assumed the decision was final. But two years after the ballot vote, in April 2004, the town’s Board of Health can again vote on the matter, and if it supports fluoridation, Gibeault and the other opponents will be back at square one.

”Part of me is thinking they’re waiting for the clock to run out,” said Gibeault of town officials.

Plainville is one of only a handful of communities in the state to reject fluoridation. Worcester, the most prominent among them, has rejected fluoridation five times.

For Plainville, finances are a concern. Marshall pointed out the uncertainty that is built into the state law that governs fluoridation approval. He said the two towns could come to an agreement on how to separate the water, and Plainville could decide to spend the money, but if the Board of Health votes in 11/2 years to again support fluoridation, the money would go to waste.

But the delay is not part of a strategy to subvert the will of the voters, said Leland Ross Jr., chairman of the Board of Water and Sewer Commissioners. ”The strategy is to bring the resolution to a completion,” he said.

The cost was debated before the April vote. Antifluoride activists argued that by state law, North Attleborough, as the town that wants fluoride, would have to bear the cost of separation.

Those who supported fluoridation said there was no such guarantee.

Health was also an issue. Supporters say fluoridation is safe and helps prevent cavities. Opponents argue that fluoride poses health risks, particularly for infants and the elderly.

Gibeault said she doesn’t know what her group’s next move will be, but promised not to give up.

”I guess the old standard of, `It doesn’t matter if you vote,’ holds true here. Citizens don’t have a say in what goes on in their own town,” she said. ”We’ll remind them every month: It’s now six months; it’s now seven months; it’s now eight months.”