Plans to add fluoride to the public water supply in Southampton and parts of Hampshire have been scrapped.
Public Health England (PHE) said it still endorsed water fluoridisation but would not proceed without backing from Southampton City Council.
NHS chiefs agreed in 2009 to add fluoride to tap water for about 200,000 people, claiming it would be beneficial for children's health.
But the scheme has never been implemented amid opposition.
Opponents claim fluoride has negative effects on the body and argue the policy would have amounted to medicating the population without consent.
John Spottiswoode, chairman of Hampshire Against Fluoridation, said: "It's excellent news. We would really like to see it stopped across the country.
"There's so much research from around the world that if you ingest fluoride over a period it's unsafe for children and adults.
"It's also immoral to forcibly medicate people. It's a toxin."
The now-abolished Southampton City Primary Care Trust proposed introducing fluoride into the city's water supply in 2008 to combat high levels of children with tooth decay.
But both Southampton City Council and Hampshire County Council have opposed the plans.
In September, PHE director Graham Bickler said the adding of fluoride to the public water supply would be down to local authorities.
PHE chief executive Duncan Selbie said: "Water fluoridation would make a big difference to the dental health of Southampton children, particularly those in the most socially deprived areas.
"We regret having to drop the scheme, but we believe it is the right decision in the circumstances."
Mr Selbie said PHE still planned to work with Southampton City Council to tackle the city's high rates of tooth decay.
About six million people - 10% of the UK's population - live in areas with fluoridated water supplies.