Gross Alpha Activity
EPA MCL
15 pCi/L
EPA has not set a health goal (MCLG) for this contaminant. This is the enforceable limit water systems must meet.
Health Effects
Increased risk of cancer
Source: EPA — National Primary Drinking Water Regulations (retrieved 2026-07-27)
Common Sources
- Erosion of natural deposits of certain minerals that are radioactive and may emit a form of radiation known as alpha radiation
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The EPA MCL for Gross Alpha Activity is 15 pCi/L. Upload your water test (PDF or a photo) and we'll email a plain-English reading of where your result lands — and every other number — free. Educational only, no medical claims.
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Water filters certified under the following NSF standards are effective at removing Gross Alpha Activity:
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Where is Gross Alpha Activity Found?
Gross Alpha Activity has been detected above EPA health guidelines in 3,075 cities serving 311.9M people across the US.
and 3,070 more cities
About the EPA MCL
This is the enforceable federal limit water systems must meet. EPA has not set a separate non-enforceable health goal (MCLG) for this contaminant.
Contaminant Type
Gross Alpha Activity is classified as a Radionuclides contaminant.
Related Radionuclides Contaminants
Check Your Water
Find out if Gross Alpha Activity is in your tap water.
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