Fluoride is a mineral that occurs naturally in all water sources, including oceans, rivers and lakes. Fluoride is also added to some community tap water, toothpastes and mouth rinses. Infants and toddlers who do not receive an adequate amount of fluoride may be at an increased risk for tooth decay since fluoride helps make tooth enamel more resistant to decay. It also helps repair weakened enamel. Bottled water may not contain fluoride; therefore, children who regularly drink bottled water or unfluoridated tap water may be missing the benefits of fluoride. If you are not sure if your tap water has fluoride, contact your local or state health department or water supplier.