Ballina will vote on Thursday on whether to reject fluoridation of its water supply. If it does, it will join nearby Lismore Council and 17 Queensland councils that have voted no to fluoride this year.

Children living in parts of northern NSW without fluoridation already have the worst teeth in the state. They have nearly double the number of decayed, missing and filled teeth compared with other children, according to the most recent dental health survey.

On tap: Fluoride has no negative effects, says chief medical officer Kerry Chant. Credit:Kate Geraghty

The state's chief medical officer, Dr Kerry Chant, travelled to Ballina this week to persuade counsellors to vote against the motion, arguing there was no scientific or health evidence to show fluoride had negative effects on health.

A decision not to proceed with water fluoridation would deny generations of Ballina residents what the survey described as one of the “most effective and socially equitable means of preventing tooth decay”.