The limit on fluoride in bottled water will soon be cut to less than 0.7 milligram per litre from the current 1.5mg standard to prevent bone abnormality and teeth discolouring especially in children.

Public Health Minister Jurin Laksanawisit said yesterday that a 2007 report from the National Statistical Office showed that 29 per cent of household drinking water came from bottled water.

Pipat Yingseri, secretary-general of the Food and Drug Administration, said water with more than 1.5mg of fluoride per litre doubled the risk of discoloured teeth among three-year-olds, compared to 0.7mg.

Only 2.24 per cent or 100 companies in the country produced bottled water with less than 0.7mg of fluoride, he said.

The World Health Organisation warned that drinking water with more than 4mg of fluoride per litre for a long time could cause bone abnormality, joint pain and disability.

The new regulation will go into effect in 180 days after publication in the Royal Gazette.