Fluoride in drinking water
850 active public water systems in 41 states had a Fluoride violation in the past three years, and 56 have one that is still unresolved.
You are on Tapcensus, an independent guide to the EPA compliance records of every public water system in the United States. This page explains Fluoride and lists the water systems whose records include a related violation. It does not show measured levels.
Is Fluoride in the records for your water system?
Enter a ZIP code, town, or street address to see the water systems that serve your area, their status, and which rules and contaminants appear in their violations.
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What it is and where it comes from
Fluoride occurs naturally in groundwater drawn from fluoride-bearing rock, and many public supplies add it at about 0.7 mg/L to reduce tooth decay. The MCL addresses excess natural levels, which are rare in surface water but possible in some groundwater.
Health effects
Above 2 mg/L: dental fluorosis (mottling/pitting of tooth enamel) in children under 8. Above 4 mg/L: skeletal fluorosis (joint pain, increased bone density) after decades of exposure.
The standard and what a violation means
EPA limit: 4 mg/L primary MCL; 2 mg/L secondary MCL (cosmetic).
Water systems with a Fluoride violation, by state
Active public water systems that reported at least one related violation to EPA in the past three years. Each state links to the list of its affected systems.
| State | Systems with violations, 3 yr | Share of active systems | Unresolved |
|---|---|---|---|
| Pennsylvania | 128 | 2% | 1 |
| Texas | 101 | 1% | 21 |
| Georgia | 66 | 3% | 1 |
| New York | 58 | 1% | 0 |
| Washington | 35 | 1% | 4 |
| Colorado | 31 | 1% | 4 |
| New Jersey | 31 | 1% | 0 |
| California | 28 | 0% | 0 |
| Montana | 26 | 1% | 1 |
| Missouri | 25 | 1% | 4 |
| Wyoming | 23 | 3% | 1 |
| Maryland | 22 | 1% | 0 |
| West Virginia | 22 | 3% | 0 |
| Oklahoma | 21 | 2% | 0 |
| Virginia | 19 | 1% | 2 |
| Connecticut | 17 | 1% | 0 |
| Arizona | 16 | 1% | 6 |
| Indiana | 15 | 0% | 0 |
| Wisconsin | 15 | 0% | 0 |
| Oregon | 14 | 1% | 1 |
| Maine | 13 | 1% | 0 |
| Idaho | 11 | 1% | 1 |
| Massachusetts | 11 | 1% | 2 |
| Utah | 11 | 1% | 0 |
| Michigan | 10 | 0% | 0 |
| Iowa | 9 | 0% | 0 |
| Illinois | 9 | 0% | 0 |
| New Mexico | 9 | 1% | 5 |
| Nevada | 7 | 1% | 0 |
| Alaska | 6 | 0% | 0 |
| Alabama | 6 | 1% | 0 |
| Mississippi | 6 | 1% | 0 |
| North Carolina | 6 | 0% | 0 |
| Vermont | 6 | 0% | 1 |
| Minnesota | 5 | 0% | 0 |
| Florida | 3 | 0% | 0 |
| New Hampshire | 3 | 0% | 1 |
| Kansas | 2 | 0% | 0 |
| South Dakota | 2 | 0% | 0 |
| Kentucky | 1 | 0% | 0 |
| North Dakota | 1 | 0% | 0 |
Largest water systems with a Fluoride violation
The ten biggest systems, by people served, whose records include a related violation in the past three years.
| System | Serves | Status | Rules violated, 3 yr | Unresolved |
|---|---|---|---|---|
|
Aqua PA Main System Montgomery County |
822,600 | 6 | 0 | |
|
Aquarion-Eastern Fairfield County Beacon Falls, Bridgeport, Darien and 17 more · Fairfield County |
351,756 | 2 | 0 | |
|
Corona, City of Corona · Riverside County |
169,380 | 6 | 0 | |
|
City of Sunnyvale Sunnyvale · Santa Clara County |
157,566 | 5 | 0 | |
|
Aqua WSC Bastrop County |
86,325 | 5 | 1 | |
|
GW Santa Cruz Water CO Maricopa · Pinal County |
84,000 | 7 | 0 | |
|
Johnson County SUD Johnson County |
65,517 | 2 | 0 | |
|
Greater Johnstown WA Riverside Cambria County |
49,500 | 7 | 0 | |
|
City of Sherman Grayson County |
43,645 | 2 | 0 | |
|
Greenlawn Water District Huntington (t) · Suffolk County |
42,000 | 3 | 0 |
About this data
A system is counted once if any of its violations in the past three years involved Fluoride, including monitoring and reporting lapses. Rules violated and status in the systems table are for the whole system, not Fluoride alone. Counts cover active systems in all 50 states and the District of Columbia.
Source: the U.S. EPA's Enforcement and Compliance History Online system (ECHO), which publishes the federal Safe Drinking Water Information System. EPA's terms and values are shown as published. The records are from EPA's data refresh of Oct 7, 2026; EPA refreshes this data quarterly, and states report to EPA with a lag of three to six months, so the newest violations may not appear yet.