Barium in drinking water
867 active public water systems in 44 states had a Barium violation in the past three years, and 15 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 Barium and lists the water systems whose records include a related violation. It does not show measured levels.
Is Barium 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.
Enter a ZIP code, town, or street address.
What it is and where it comes from
Barium is a naturally occurring alkaline earth metal found in mineral deposits, particularly barite and witherite. It enters drinking water through dissolution of natural deposits and, to a lesser extent, from industrial discharge — metal refining, coal combustion, and oil and gas drilling operations. Groundwater drawn from barium-bearing rock can carry detectable levels.
Health effects
Short-term exposure above the MCL can cause increases in blood pressure. Chronic exposure is associated with cardiovascular effects, kidney damage, and gastrointestinal disturbance. The general population is at risk; those with pre-existing hypertension or kidney disease face greater concern.
The standard and what a violation means
EPA limit: 2 mg/L (2,000 ppb).
Water systems with a Barium 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 |
|---|---|---|---|
| Pennsylvania | 122 | 2% | 0 |
| Texas | 73 | 1% | 0 |
| Illinois | 72 | 1% | 3 |
| Georgia | 61 | 3% | 0 |
| New York | 59 | 1% | 0 |
| Michigan | 48 | 0% | 0 |
| Colorado | 29 | 1% | 4 |
| Indiana | 29 | 1% | 0 |
| West Virginia | 28 | 4% | 0 |
| New Jersey | 27 | 1% | 0 |
| California | 23 | 0% | 0 |
| Wyoming | 22 | 3% | 0 |
| Missouri | 21 | 1% | 2 |
| Washington | 21 | 0% | 0 |
| Montana | 20 | 1% | 0 |
| Oklahoma | 20 | 2% | 0 |
| Idaho | 19 | 1% | 1 |
| Connecticut | 17 | 1% | 0 |
| Virginia | 15 | 1% | 0 |
| Oregon | 13 | 1% | 0 |
| Maine | 12 | 1% | 0 |
| Wisconsin | 12 | 0% | 0 |
| Massachusetts | 10 | 1% | 2 |
| Utah | 10 | 1% | 0 |
| Iowa | 8 | 0% | 0 |
| Nevada | 8 | 1% | 0 |
| Alaska | 7 | 1% | 0 |
| Maryland | 7 | 0% | 0 |
| Mississippi | 7 | 1% | 0 |
| Vermont | 7 | 1% | 2 |
| Arizona | 6 | 0% | 1 |
| North Carolina | 6 | 0% | 0 |
| Alabama | 5 | 1% | 0 |
| Minnesota | 5 | 0% | 0 |
| Florida | 4 | 0% | 0 |
| Rhode Island | 3 | 1% | 0 |
| Kansas | 2 | 0% | 0 |
| New Hampshire | 2 | 0% | 0 |
| South Dakota | 2 | 0% | 0 |
| Hawaii | 1 | 1% | 0 |
| Kentucky | 1 | 0% | 0 |
| North Dakota | 1 | 0% | 0 |
| New Mexico | 1 | 0% | 0 |
| Ohio | 1 | 0% | 0 |
Largest water systems with a Barium 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 | |
|
Tigard, City of Washington County |
62,500 | 2 | 0 | |
|
Greater Johnstown WA Riverside Cambria County |
49,500 | 7 | 0 | |
|
Greenlawn Water District Huntington (t) · Suffolk County |
42,000 | 3 | 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 Barium, including monitoring and reporting lapses. Rules violated and status in the systems table are for the whole system, not Barium 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.