Radium-228 in drinking water
463 active public water systems in 25 states had a Radium-228 violation in the past three years, and 27 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 Radium-228 and lists the water systems whose records include a related violation. It does not show measured levels.
Is Radium-228 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
Radium-228 is a naturally occurring beta-emitting radioactive isotope in the thorium-232 decay chain. Like radium-226 it leaches from bedrock into groundwater and is found in deep aquifers in granite-rich regions. It is regulated both individually and as part of the combined radium standard. Its half-life of approximately 5.75 years makes it a persistent groundwater concern.
Health effects
Radium-228 accumulates in bone and delivers a beta radiation dose internally, increasing the risk of bone cancer over time. It also decays to radon-220 and other short-lived isotopes, contributing additional radiation dose. As with all radionuclides there is no established safe threshold — any exposure carries some incremental cancer risk.
The standard and what a violation means
EPA limit: 5 pCi/L (when measured individually; combined Ra-226 + Ra-228 MCL also applies).
Water systems with a Radium-228 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 | 132 | 2% | 3 |
| Indiana | 48 | 1% | 0 |
| New Jersey | 45 | 1% | 2 |
| Utah | 31 | 3% | 4 |
| New York | 26 | 0% | 0 |
| Idaho | 25 | 1% | 3 |
| West Virginia | 24 | 3% | 2 |
| Wisconsin | 22 | 0% | 7 |
| Wyoming | 20 | 3% | 2 |
| Alabama | 13 | 2% | 0 |
| North Carolina | 10 | 0% | 1 |
| Ohio | 10 | 0% | 0 |
| Arizona | 8 | 0% | 1 |
| Missouri | 8 | 0% | 0 |
| Vermont | 8 | 1% | 0 |
| Tennessee | 6 | 1% | 0 |
| Nevada | 5 | 1% | 0 |
| Massachusetts | 4 | 0% | 0 |
| Michigan | 4 | 0% | 0 |
| Montana | 4 | 0% | 1 |
| Maryland | 3 | 0% | 0 |
| South Dakota | 3 | 0% | 0 |
| North Dakota | 2 | 1% | 0 |
| California | 1 | 0% | 0 |
| Rhode Island | 1 | 0% | 1 |
Largest water systems with a Radium-228 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 |
|---|---|---|---|---|
|
Tucson City of Tucson · Pima County |
732,906 | 3 | 0 | |
|
Corona, City of Corona · Riverside County |
169,380 | 6 | 0 | |
|
GW Santa Cruz Water CO Maricopa · Pinal County |
84,000 | 7 | 0 | |
|
Fairhope, City of Fairhope · Baldwin County |
59,850 | 1 | 0 | |
|
Perth Amboy Water Department Perth Amboy City · Middlesex County |
52,328 | 2 | 0 | |
|
Tooele City Water System Tooele County |
41,770 | 2 | 0 | |
|
South Alabama Utilities Water System Citronelle · Mobile County |
39,249 | 3 | 0 | |
|
Winslow Twp Dmu Winslow Twp · Camden County |
39,174 | 6 | 0 | |
|
Aqua NJ Hamilton Square Hamilton Twp · Mercer County |
39,128 | 4 | 2 | |
|
Jackson Twp Mua Jackson Twp · Ocean County |
37,224 | 3 | 0 |
About this data
A system is counted once if any of its violations in the past three years involved Radium-228, including monitoring and reporting lapses. Rules violated and status in the systems table are for the whole system, not Radium-228 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.