Fluoride in drinking water can cause mottling of children's teeth, usually in children less than nine years old. Mottling, also known as dental fluorosis, may include brown staining and/or pitting of teeth, and occurs only in developing teeth before they erupt from the gums. Because children may get mottled teeth at levels above 2.0 mg/L, EPA has set a non-enforceable secondary maximum contaminant level of 2.0 mg/L. EPA has also set an enforceable maximum contaminant level of 4.0 mg/L to prevent against adverse health effects.
To help determine the cause(s) of aesthetic or cosmetic effects from your drinking water, contact your local drinking water system. Additional guidance for household well owners is available at http://water.epa.gov/drink/info/well/index.cfm. General information on nuisance chemicals is available at http://water.epa.gov/drink/contaminants/secondarystandards.cfm .