Variation among fluoride concentrations of water from domestic wells in a four-county area.

Water samples from domestic wells in a four-county area of New Mexico were analyzed for fluoride over a twenty-four month period, using a specific ion electrode. Of the 503 nonrandomly selected samples analyzed, 33 (6.6 percent) had less than 0.3 ppm, 372 (73.9 percent) had between 0.3 and 0.7 ppm and 98 (19.5 percent) had greater than 0.7 ppm of fluoride. The Council on Dental Therapeutics of the American Dental Association considers fluoride concentrations of greater than 0.7 ppm to be acceptable caries preventive levels in drinking water. Variation in fluoride concentration was found at all well depth intervals considered. It is important for dentists, physicians and nurse practitioners to be aware of the potential for variation of fluoride concentrations among domestic wells. When assessing a child's fluoride needs, the fluoride concentration of his or her drinking water must be known in order to optimize the benefits of fluoride supplements and to minimize the risk of enamel fluorosis. The fluoride level of community water systems is generally known by a town's water or health department. Water from domestic wells, however, must be assayed for fluoride on an individual basis to make the determination.