Adding fluoride to drinking water for more than 270,000 people in Windsor, LaSalle and Tecumseh could hinge in part on 50 households and businesses in Lakeshore.

In a potential game changer in the contentious debate over the chemical, Lakeshore, which gets some of its water from Windsor via Tecumseh, wants to vote on whether the city can resume fluoridation.

But no one knows if Lakeshore is entitled to a vote.

“We’ve made it known to them (Windsor and Tecumseh) we would like a say,” said Lakeshore Mayor Tom Bain. “We just want to have a voice in it since it’s coming to our people.”

Windsor’s city council voted in December to resume adding fluoride to its water. The city also supplies water to Tecumseh and LaSalle. Ontario’s Fluoridation Act states that if several municipalities get their water from the same utility, they can add fluoride only if the majority of communities approves. Everyone here thought that meant either Tecumseh or LaSalle have to approve fluoridation, too.

But part of Lakeshore gets its water from Tecumseh, Joe Bachetti, Tecumseh’s deputy mayor, pointed out.

“If we’re going to reintroduce fluoride, why isn’t Lakeshore included?” he asked. “They’ve got a voice. Or are we just going to ignore them and say, ‘Too bad’?

“To me that’s a game changer,” he said.

Instead of needing approval from one more municipality, Windsor’s decision could need approval from two.

The mayors of Tecumseh and LaSalle are split. Tecumseh Mayor Gary McNamara, chairman of the board of the Windsor-Essex County Health Unit, which reported an alarming increase in cavities in children since Windsor removed fluoride from its water in 2013, supports it. LaSalle Mayor Marc Bondy opposes it.

That could leave Lakeshore with the deciding vote.

Both the Windsor Utilities Commission and Lakeshore are consulting lawyers.

“We believe they will have a vote,” said Helga Reidel, president and CEO of Enwin, which manages water for WUC. “But these are complicated pieces of legislation so we’re not going to jump to any premature conclusions. We are letting a lawyer look through the legislation and tell us if there are any nuances we need to be cognizant of. We want to do the right thing and make sure it’s handled correctly.”

Only 50 households and businesses in Lakeshore — less than one percent — get their water from Tecumseh. They’re mostly along Manning Road and Scott Sideroad near the border with Tecumseh. The rest, depending on where they live, get it from Lakeshore, Union Water Supply System in Kingsville and Chatham-Kent.

WUC bills Tecumseh, not Lakeshore, for the water that goes to Lakeshore.

“We know we’re just a small piece of the pie,” said Bain. But, he said, “it’s a contentious issue, and council would just like to be heard.”

Lakeshore should “definitely” get a vote, said Bachetti, who voted in 2012 to recommend that Windsor stop fluoridation and says he’ll need “compelling evidence” to change his position this time.

“If they’re (Lakeshore) getting the water, they need a voice. One (household) suffices for me. There are strong arguments on both sides. It’s a very difficult issue.”

Lakeshore was not consulted when Windsor voted in 2013 to remove fluoride from its water. The town had already voted in 2011 to remove fluoride from its plant in Stoney Point, the only one supplying Lakeshore that still used the chemical.

If fluoride is added to the water again, it could leave Lakeshore split, with some people getting it and some not getting it.

“We’ll make a decision about the rest of the municipality,” said Bain. “If part of (the town) gets it and part doesn’t, that’ll be the reality.”

Bain voted to stop fluoridation in 2011, when the majority of council decided fluoride isn’t needed in water because there are other ways to protect teeth, like fluoridated toothpaste.

“But those facts seem to have changed,” he said, calling the health unit’s report “a major factor.”

“I think it needs re-evaluation,” he said of the issue. “I’m waiting to hear both sides of the argument. I want to see all the facts and figures on it before I make a decision.”

Tecumseh’s council was to address the issue Tuesday, but a report by administrators states they’re still waiting for information, including Lakeshore’s role.

LaSalle doesn’t expect to vote on it until March because it’s waiting for the same information.