Combined Uranium in drinking water
909 active public water systems in 38 states had a Combined Uranium violation in the past three years, and 61 had one in the latest quarter of EPA's data.
You are on Tapcensus, an independent guide to the EPA compliance records of every public water system in the United States. This page explains Combined Uranium and lists the water systems whose records include a related violation. It does not show measured levels.
Is Combined Uranium 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
Uranium is a naturally occurring radioactive heavy metal found in rock and soil formations across the United States. It leaches into groundwater through weathering of uranium-bearing minerals, and is more prevalent in granite-rich and other uranium-bearing geologies. Mining and milling operations can also elevate uranium in nearby water supplies.
Health effects
Uranium poses both radiological and chemical health risks. Chronic exposure is primarily associated with kidney damage due to its chemical toxicity as a heavy metal. The radiological risk — increased cancer probability — is also present but secondary to the nephrotoxic concern at drinking water concentrations. There is no safe threshold for radiation exposure.
The standard and what a violation means
EPA limit: 0.030 mg/L (30 µg/L).
Water systems with a Combined Uranium 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 | In violation, latest quarter |
|---|---|---|---|
| Oklahoma | 110 | 9% | 0 |
| Oregon | 104 | 4% | 9 |
| Georgia | 94 | 4% | 4 |
| Pennsylvania | 81 | 1% | 2 |
| Colorado | 58 | 3% | 5 |
| California | 55 | 1% | 9 |
| Texas | 50 | 1% | 0 |
| Michigan | 45 | 0% | 0 |
| New Jersey | 36 | 1% | 2 |
| Idaho | 31 | 2% | 3 |
| Alaska | 30 | 2% | 2 |
| Virginia | 24 | 1% | 0 |
| New York | 23 | 0% | 0 |
| Wyoming | 22 | 3% | 2 |
| Arizona | 18 | 1% | 6 |
| North Carolina | 17 | 0% | 3 |
| Nevada | 16 | 3% | 1 |
| Connecticut | 10 | 0% | 1 |
| Wisconsin | 10 | 0% | 3 |
| New Hampshire | 7 | 0% | 0 |
| New Mexico | 7 | 1% | 3 |
| Vermont | 7 | 1% | 0 |
| Montana | 6 | 0% | 1 |
| Utah | 6 | 1% | 1 |
| Washington | 6 | 0% | 2 |
| Maine | 5 | 0% | 0 |
| Nebraska | 5 | 0% | 1 |
| Kansas | 4 | 0% | 0 |
| North Dakota | 4 | 1% | 0 |
| South Dakota | 4 | 1% | 0 |
| Illinois | 3 | 0% | 0 |
| Iowa | 2 | 0% | 1 |
| Massachusetts | 2 | 0% | 0 |
| Mississippi | 2 | 0% | 0 |
| Rhode Island | 2 | 0% | 0 |
| District of Columbia | 1 | 7% | 0 |
| Florida | 1 | 0% | 0 |
| Missouri | 1 | 0% | 0 |
Largest water systems with a Combined Uranium 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 |
|---|---|---|---|---|
|
Denver Water Board Denver County |
1,287,000 | 3 | 0 | |
|
Tucson City of Tucson · Pima County |
732,906 | 3 | 0 | |
|
Corona, City of Corona · Riverside County |
169,380 | 6 | 0 | |
|
Albany Albany · Dougherty County |
101,245 | 2 | 0 | |
|
Aqua WSC Bastrop County |
86,325 | 5 | 1 | |
|
GW Santa Cruz Water CO Maricopa · Pinal County |
84,000 | 7 | 0 | |
|
Carson City Public Works Carson City · County |
59,000 | 1 | 0 | |
|
Moore Public Works Authority Cleveland County |
55,083 | 4 | 0 | |
|
Grand Island, City of Grand Island · Hall County |
51,478 | 1 | 0 | |
|
Winslow Twp Dmu Winslow Twp · Camden County |
39,174 | 6 | 0 |
About this data
A system is counted once if any of its violations in the past three years involved Combined Uranium, including monitoring and reporting lapses. Rules violated and status in the systems table are for the whole system, not Combined Uranium 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.