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Arsenic in Well Water: The EPA Limit and Treatment That Actually Works
WellsApril 13, 2026·8 min read

Arsenic in Well Water: The EPA Limit and Treatment That Actually Works

By Joe Letorney | 30-year water treatment expert · Former WQA Certified Water Treatment Specialist (CWS), Level VI

Arsenic is a natural groundwater contaminant in many regions. Here is how to test, when 10 ppb matters, and what treatment options are common.

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Arsenic in groundwater is common in parts of the Southwest, New England, Appalachia, and the Midwest. It is odorless and tasteless — testing is the only way to know your level.

EPA standard

The MCL for arsenic in public drinking water is 10 μg/L (10 ppb). Private wells are not federally regulated — owners must test and treat.

Health notes

Long-term exposure to elevated arsenic is associated with increased cancer risk and other health effects. If your well is above the EPA limit, take action for drinking water — not just aesthetics.

Treatment

Point-of-use reverse osmosis is widely used for arsenic reduction. Specialized adsorptive media systems exist for whole-house applications — design and maintenance depend on your chemistry and flow rate.

Retest after install: Always verify treatment with follow-up lab testing at the tap.
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