Gross Beta Activity
EPA MCL
4 mrem/year
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
- Decay of natural and man-made deposits of certain minerals that are radioactive and may emit forms of radiation known as photons and beta radiation
Is your Gross Beta Activity result safe? Get a free reading
The EPA MCL for Gross Beta Activity is 4 mrem/year. 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 Beta Activity:
Filter recommendations for this contaminant are being updated.
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Where is Gross Beta Activity Found?
Gross Beta Activity has been detected above EPA health guidelines in 255 cities serving 3.7M people across the US.
and 250 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 Beta Activity is classified as a Radionuclides contaminant.
Related Radionuclides Contaminants
Check Your Water
Find out if Gross Beta Activity is in your tap water.
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