Forty-nine percent of voters in the Southland, Central Otago and South Otago districts are against water fluoridation, results from a non-biding referendum have shown.
When voters in Central Otago and parts of Southland and South Otago opened their local election ballot papers last month, they were also given a chance to take part in a poll asking whether they would like their water fluoridated.
Results from that poll show 49 percent of voters were against adding fluoride, while 36.5 percent were for, and 14.5 were neither for nor against.
Both pro and anti-fluoride campaigners had spent weeks before and after the elections calling for people to look into the issue.
Fluoride supporters said it was a proven safe and effective way of reducing tooth decay in children and adults. Those against argued it could cause health problems.
In Southland, Ohai was the only town of eight polled to support fluoridation, with residents narrowly voted for fluoride by 30 votes to 26.
However, in neighbouring Nightcaps, the majority voted against, 41 to 28.
The two towns share the same water supply.
Lumsden residents were evenly divided with 62 votes recorded either side.
Tuatapere residents strongly opposed fluoridation, voting 134 to 63. Despite this, nearly 80 percent of 5-year-olds have had tooth decay in some areas of western Southland.
Voting took place in Tuatapere, Te Anau, Riverton, Otautau, Winton, Ohai/Nightcaps, Oamaru, Tapanui, Milton, Kaitangata, Cromwell, Clyde and Alexandra.
Southland District Council communications officer Kerry Dohig said council would discuss the results later.