Barium in well water: limits and what to do
The EPA limit for barium is 2 mg/L and the Ontario standard is 1 mg/L. Most wells are far below. Above the limit, long term exposure can raise blood pressure.
- US (EPA)
- 2 mg/L.
- Ontario
- 1 mg/L.
What it is
Barium occurs naturally in some rock, especially limestone and shale. Higher levels are sometimes found near oil and gas drilling or industrial sites.
What your number means
- Within limitsBelow 1 mg/L
Under both the US and Ontario limits.
- Worth a look1 to 2 mg/L
Above the Ontario standard, under the EPA limit. Retest, and talk to your health department if you are in Ontario.
- Above limitAbove 2 mg/L
Above the EPA limit. Use another source for drinking and ask about treatment.
What to do
- Retest to confirm a high result.
- A water softener (cation exchange) or reverse osmosis removes barium.
- If you are near drilling or industry, mention it to your health department.
How often to test
With a full panel every 3 to 5 years.
Common questions
Is barium in well water common?
Low levels are common and harmless. Levels above the limit are rare and usually natural.
Will my water softener remove barium?
Yes, a standard cation exchange softener removes barium along with hardness, as long as it is maintained.
Sources: EPA drinking water regulations; Ontario Drinking Water Quality Standards (O. Reg. 169/03). Limits checked November 2026.