Barium in Drinking Water
Barium is a naturally occurring alkaline earth metal found in sedimentary rock formations across the United States. It enters groundwater through natural geological weathering and from oil and gas drilling operations that produce barium-containing brine. The EPA MCL is 2 mg/L. At elevated levels, barium raises blood pressure and can cause cardiovascular and kidney effects. Barium violations in public water systems are uncommon but occur in parts of the Midwest and Southeast where sedimentary geology concentrates barium in deep aquifers.
Quick Answer
Barium (Ba) occurs naturally in barite (barium sulfate) and witherite (barium carbonate) mineral deposits found primarily in Illinois, Missouri, Arkansas, Georgia, and Tennessee. It is chemically similar to calcium and strontium and behaves as an alkaline earth metal in groundwater. Industrial uses include drilling muds in oil and gas exploration, paint pigments, and glass manufacturing. Oil and gas production brine — produced water — often contains elevated barium that can contaminate groundwater if improperly disposed. Barium sulfate is essentially insoluble (which is why it is used safely in medical imaging), but barium chloride and other soluble forms can occur in groundwater.
Why Is Barium in Drinking Water a Concern?
Barium is not a widespread public health problem — MCL exceedances are uncommon and concentrated in specific geological areas. Its primary health concern is cardiovascular: barium affects muscle function by competing with potassium and can cause hypertension and cardiac arrhythmia at elevated levels. For most Americans, barium in drinking water is well within the MCL and poses negligible risk. The concern is localized to communities drawing from deep sedimentary aquifers in the Midwest and to areas where oil and gas production waste may have contaminated groundwater.
People served by groundwater systems drawing from Mississippian and Devonian limestone and shale formations in Illinois, Missouri, Kentucky, Tennessee, and Arkansas face the highest natural barium exposure. Well owners in these areas and near oil and gas production sites where produced water may have contaminated groundwater should be aware of barium. The general U.S. public is at very low risk.
Health Effects of Barium in Drinking Water
Hypertension — barium stimulates vascular smooth muscle, raising blood pressure with chronic exposure above the MCL
Cardiac arrhythmia — barium competes with potassium in cardiac muscle cells, potentially causing irregular heartbeat at high acute doses
Kidney damage with chronic high-level exposure
Muscle weakness and paralysis at very high acute doses — well above concentrations found in drinking water
No established health effects at levels below the 2 mg/L MCL for the general population
How Does Barium Get Into Drinking Water?
Natural dissolution from barite and witherite mineral deposits in sedimentary rock
Oil and gas drilling muds — barium sulfate is used as a weighting agent; can enter groundwater from improper waste disposal
Produced water (brine) from oil and gas wells — often contains elevated barium; disposal by injection or surface storage can contaminate groundwater
Mining of barite for industrial uses
Paint pigment manufacturing (barium sulfate white pigment) — historical industrial contamination sites
Regulatory Limit
EPA Maximum Contaminant Level (MCL)
2 mg/L
The EPA MCL for barium is 2 milligrams per liter (mg/L), set in 1992. The MCLG is also 2 mg/L, reflecting the EPA's view that the MCL is adequately health-protective. At 2 mg/L, the EPA does not consider barium to pose an unreasonable health risk for the general population. The WHO guideline is 1.3 mg/L — more stringent than the U.S. standard.
How to Test for Barium in Your Water
Barium is included in comprehensive metals panels at certified laboratories and is not typically in standard water quality tests. A barium-specific test costs $15–$25 or is included in metals panels for $75–$150. Well owners in Mississippian limestone regions of Illinois, Missouri, and Kentucky, or near oil and gas production, should include barium in comprehensive testing. Public utilities test and report barium in Consumer Confidence Reports.
How to Remove Barium from Drinking Water
These treatment methods have demonstrated effectiveness for Barium removal.
Reverse Osmosis
Reverse osmosis (RO) is the most comprehensive point-of-use water treatment technology available for residential use. It removes 90–99% of dissolved contaminants including PFAS, lead, arsenic, nitrates, and disinfection byproducts by forcing water through a semi-permeable membrane with pores of approximately 0.0001 microns.
Water Softener
A salt-based water softener is the standard whole-home solution for hard water. It uses ion exchange to replace dissolved calcium and magnesium — the minerals responsible for scale, soap scum, and appliance damage — with sodium ions. Softeners protect plumbing and appliances but do not address health-based contaminants.
Frequently Asked Questions
Related Pages
Data Sources & Provenance
All data on this page is sourced from official U.S. government or public datasets.
Quick Reference
Category
Heavy Metals
Risk Level
low
EPA Limit
2 mg/L
Most at Risk
People served by groundwater systems drawing from Mississippian and Devonian limestone and shale formations in Illinois, Missouri, Kentucky, Tennessee, and Arkansas face the highest natural barium exposure.
Well Water Relevant
Yes
Barium by State
Treatment Options