Fluoride in Drinking Water

Data source: U.S. EPA

ZipCheckup tracks Fluoride in U.S. drinking water against the EPA limit of 4.0 mg/L under the National Primary Drinking Water Regulations. Fluoride carries a moderate health-risk designation.

What Is Fluoride in Drinking Water?

Fluoride occurs naturally in water from the dissolution of fluoride-bearing minerals and is also added to many public water supplies to prevent tooth decay. While community water fluoridation at 0.7 mg/L is endorsed by the CDC as one of the top public health achievements of the 20th century, elevated natural fluoride levels above the EPA MCL of 4.0 mg/L can cause health problems.

Health Effects

• At optimal levels (0.7 mg/L): prevents tooth decay
• Above 2.0 mg/L (SMCL): may cause dental fluorosis (cosmetic tooth discoloration) in children
• Above 4.0 mg/L (MCL): risk of skeletal fluorosis — bone pain, joint stiffness, and increased fracture risk
• Long-term high exposure: possible links to thyroid effects and neurodevelopmental concerns

EPA Standards

• MCL: 4.0 mg/L — enforceable standard to prevent skeletal fluorosis
• SMCL: 2.0 mg/L — secondary (non-enforceable) standard to prevent dental fluorosis
• Optimal fluoridation level: 0.7 mg/L (recommended by HHS since 2015)

How to Remove Fluoride

Standard carbon filters do NOT remove fluoride. Effective methods:

• Reverse osmosis (RO) — removes 90–95% of fluoride
• Activated alumina — specialized media for fluoride removal
• Distillation — effective but slow