Gross Alpha, Excl. Radon and U in drinking water
1,149 active public water systems in 41 states had a Gross Alpha, Excl. Radon and U violation in the past three years, and 89 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 Gross Alpha, Excl. Radon and U and lists the water systems whose records include a related violation. It does not show measured levels.
Is Gross Alpha, Excl. Radon and U in the records for your water system?
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What it is and where it comes from
Gross alpha particle activity is a screening measurement of all alpha-emitting radionuclides in water, excluding radon and uranium (which are regulated separately). If gross alpha exceeds 5 pCi/L, further analysis is required to identify specific radionuclides. Elevated gross alpha typically indicates water drawn from deep aquifers in contact with uranium- or thorium-bearing bedrock.
Health effects
Alpha-emitting radionuclides accumulate in bone and soft tissue, delivering sustained internal radiation doses that increase lifetime cancer risk. There is no established safe threshold for ionizing radiation. Individual contributors such as radium-226 and polonium-210 have their own MCLs; gross alpha serves as a cost-effective screening tool that triggers more specific radionuclide analysis when exceeded.
The standard and what a violation means
EPA limit: 15 pCi/L (excluding radon and uranium).
Water systems with a Gross Alpha, Excl. Radon and U 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 | 175 | 2% | 5 |
| Oregon | 133 | 5% | 9 |
| Oklahoma | 109 | 8% | 0 |
| Georgia | 101 | 4% | 11 |
| Texas | 66 | 1% | 0 |
| New Jersey | 55 | 2% | 3 |
| Colorado | 51 | 2% | 11 |
| Indiana | 48 | 1% | 0 |
| Alaska | 33 | 2% | 1 |
| Utah | 33 | 3% | 4 |
| Idaho | 30 | 1% | 3 |
| Wisconsin | 26 | 0% | 10 |
| West Virginia | 25 | 3% | 2 |
| Virginia | 23 | 1% | 1 |
| Montana | 22 | 1% | 3 |
| North Carolina | 22 | 0% | 5 |
| Wyoming | 20 | 3% | 2 |
| Minnesota | 19 | 0% | 11 |
| Iowa | 18 | 1% | 2 |
| Michigan | 16 | 0% | 0 |
| Alabama | 15 | 3% | 0 |
| Arizona | 15 | 1% | 1 |
| California | 15 | 0% | 1 |
| Vermont | 13 | 1% | 0 |
| Connecticut | 10 | 0% | 1 |
| South Dakota | 8 | 1% | 0 |
| New Mexico | 6 | 1% | 0 |
| Tennessee | 6 | 1% | 0 |
| Maine | 5 | 0% | 1 |
| Washington | 5 | 0% | 1 |
| Florida | 4 | 0% | 0 |
| Massachusetts | 4 | 0% | 0 |
| Maryland | 4 | 0% | 0 |
| North Dakota | 4 | 1% | 0 |
| New Hampshire | 3 | 0% | 0 |
| New York | 2 | 0% | 1 |
| District of Columbia | 1 | 7% | 0 |
| Kansas | 1 | 0% | 0 |
| Nevada | 1 | 0% | 0 |
| Rhode Island | 1 | 0% | 0 |
| South Carolina | 1 | 0% | 0 |
Largest water systems with a Gross Alpha, Excl. Radon and U 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 | |
|
Tucson City of Tucson · Pima County |
732,906 | 3 | 0 | |
|
Kalamazoo Kalamazoo · Kalamazoo County |
192,992 | 2 | 0 | |
|
Albany Albany · Dougherty County |
101,245 | 2 | 0 | |
|
Aqua WSC Bastrop County |
86,325 | 5 | 1 | |
|
Waldorf Charles County Dpw Charles County |
84,296 | 2 | 0 | |
|
GW Santa Cruz Water CO Maricopa · Pinal County |
84,000 | 7 | 0 | |
|
New Design Frederick County Frederick County |
74,911 | 1 | 0 | |
|
East Cherry Creek Valley Wsd Arapahoe County |
66,130 | 1 | 0 | |
|
Hampton Shaler Water Authority Allegheny County |
61,949 | 1 | 0 |
About this data
A system is counted once if any of its violations in the past three years involved Gross Alpha, Excl. Radon and U, including monitoring and reporting lapses. Rules violated and status in the systems table are for the whole system, not Gross Alpha, Excl. Radon and U 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.