A health trust has become the first to force through a move to add fluoride to tap water to fight tooth decay in children.
The decision was made using new laws to introduce fluoridation, although three in four members of the public and a county council opposed it.
Adding fluoride to water has been described by critics as ‘mass medication’ of the population because, unlike chlorine, it is not added to make supplies safe.
Around 200,000 people in Southampton will be affected in an area where four in ten children have a filling by school age.
Dentists said it would reduce the number of decayed teeth.
Just 10 per cent of England’s water is fluoridated, covering 5.5million people, mainly in the north-east and west Midlands.
The last fluoridation scheme was introduced in 1985, but the Health Secretary last year called for further schemes after consultation, saying most people were in favour.
The decision by South Central Strategic Health Authority to back fluoridation is the first under 2003 laws giving health authorities powers to demand the service from water companies.