The town's residents are among the one in 10 Australians drinking tap water that lacks fluoride.

Councillors voted on Monday night to press for changes to help improve people's oral health.

It was "truly unbelievable" that in modern times more than 40 per cent of Victorian children had signs of tooth decay, Cr Julie Sloan said.

"We know it [a lack of fluoridated water] is not the only cause but it is a highly significant factor," she said.

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Coliban Water has recently upgraded a plant in the area, potentially paving the way for change, Cr Margaret O'Rourke said.

"It's ... the second largest population base in Greater Bendigo and it's quite remarkable that they don't have fluoridation already," she said.

It would cost $920,000 to fluoridate Heathcote's water supply, council staff estimate.

The council's advocacy would back a campaign being run by community groups including Heathcote Health, Cr Matthew Evans said.

The council will draft letters to state decision-makers by the end of July, with the mayor and some councillors likely to follow up with advocacy of their own, he said.

Medical experts used a 2017 public statement to declare fluoride levels in drinking water safe in a bid to allay concerns from some members of Australia's public.

"There is no reliable evidence of an association between community water fluoridation at current Australian levels and any health problems," federal government body the National Health and Medical Research Council said.

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