If you add fluoridated water to your infant's baby formula, you may be putting your child at risk of developing dental fluorosis, a harmless cosmetic condition manifested by brown, mottled or discolored enamel.

Although fluoride - found naturally in all water and foods - is necessary to prevent tooth decay, in infants and children regular fluoride intake above optimal amounts can cause fluorosis in developing teeth. .

Though breast milk and most ready-to-feed formulas contain infant-safe fluoride levels, parents must be careful with concentrate formulas that require adding water. Community water or well sources often contain fluoride levels higher than 1.2 ppm, the highest amount proven to be beneficial in preventing tooth decay.

When formula concentrations need to be diluted, it is recommended parents use bottled water that is fluoride-free or low in fluoride water or tap water from a reverse osmosis home water filtration system, which removes most of the fluoride.

"If your child's teeth develop brown spots, visit your dentist to check for fluorosis," says Academy of General Dentistry spokesperson James Tennyson, DDS. "It also could signal tooth decay, in which case your child may be prescribed fluoride supplements."

"If you correct a fluorosis problem in your child's first primary teeth," says Dr. Tennyson. "Your child probably won't have a problem when the permanent teeth erupt at age 5 or 6."

Dr. Tennyson also recommends checking your water source's fluoride levels by collecting a fresh sample in a sterile container and taking it to your local health or water department. Or, your dentist may be able to test your sample if his office has a colorimeter, which can determine the concentration of fluoride by comparing the sample to a standard.