Term Identity
What the term means in an annual report
Gross alpha is a screening and compliance measurement of alpha particle activity under a defined federal scope.
Why it may appear
Systems report gross-alpha monitoring as its own radionuclide measurement rather than as an identification of a single isotope.
How it may be printed
Reports may say Alpha Emitters or Gross Alpha and show activity in pCi/L with a sample period and criterion fields.
- Other names you may see
- Alpha Emitters; Gross Alpha; Gross alpha particle activity
- Common report labels
- Alpha Emitters; Gross Alpha
Evidence
Official sources for this explainer
Use official federal, state, utility, or report sources before treating a page as final.
- Supports
- Gross-alpha identity; Radionuclide distinctions
- Retrieved
- 2026-07-11
- Reviewed
- 2026-07-11
Federal regulation
- Supports
- Gross-alpha scope; Exclusions and MCL context
- Retrieved
- 2026-07-11
- Reviewed
- 2026-07-11
- Supports
- Annual-report purpose and reporting context; Report-period interpretation and official next steps
- Retrieved
- 2026-07-11
- Reviewed
- 2026-07-11
Regulatory Context
How to read the applicable rule language
Use this Gross alpha particle activity context to read a report's printed fields; it does not replace the report or the current official rule.
Framework
The federal gross-alpha standard includes radium-226 but excludes radon and uranium. It must remain separate from combined radium, beta/photon radioactivity, and uranium mass concentration.
Limit or program terms
- MCL
- MCLG
- Gross activity
Units and source context
Gross-alpha activity is commonly reported in pCi/L. It is an activity measure, not a mass concentration or identification of one alpha emitter.
What this page does not duplicate
Use the report's exact activity value and unit. Do not infer which isotope produced the result.
No standalone numeric limit table is rendered here. Read the source report's printed criterion and the current official source together.
Interpretation Boundaries
What a listed result does not establish
These Gross alpha particle activity boundaries apply to every report row connected to this explainer.
Household-level boundary
A system report's gross-alpha result does not establish current conditions at a particular tap.
What to verify next
Continue Reading
Related explainers and report-reading guides
Read about topics related to Gross alpha particle activity, or use a guide to understand the report as a whole.
Radionuclides
Combined radium 226 and 228
Combined radium is the sum of radium-226 and radium-228 results for the federal drinking-water standard. It is not a general page for every radionuclide.
Read the Combined radium 226 and 228 contaminant guideRadionuclides
Beta particle and photon radioactivity
Beta particle and photon radioactivity uses a dose-based federal standard. A 50 pCi/L gross-beta screening level is not the federal MCL.
Read the Beta particle and photon radioactivity contaminant guideRadionuclides
Uranium
Uranium is a regulated radionuclide reported as a mass concentration. It must remain separate from gross alpha activity, combined radium, and beta/photon dose context.
Read the Uranium contaminant guideHow to read a water quality report
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View What public water data can and cannot tell you