Water fluoridation
Health and dental organizations worldwide have endorsed its safety and effectiveness. Its use began in 1945, following studies of children in a region where higher levels of fluoride occur naturally in the water. Further research showed that moderate fluoridation prevents tooth decay.
Bottled water
In some areas, tap water may contain added fluoride, which helps prevent tooth decay and cavities. Some bottled water manufacturers in the United States add fluoride to their product, or provide a fluoridated bottled water product. The Food and Drug Administration of the United States does not require bottled water manufacturers to list the fluoride content on the label. However, unlike tap water where the amount of fluoride added by municipalities to drinking water is not federally regulated, the FDA has set specific limits for how much fluoride may be found in bottled water. Water fluoridation remains controversial in countries that require it (the United States, United Kingdom, Ireland, Canada, Australia, and a handful of other countries).Several studies have examined the content of fluoride and other chemicals in bottled water as well as the accuracy of these values as printed on the labels showing some significant difference between labeled and measured value.