Gross alpha particles in Tap Water
Gross alpha is a combined measure of alpha-particle radioactivity in water, a screening figure for naturally occurring radionuclides such as radium and polonium (excluding radon and uranium).
Natural radioactive decay of uranium and thorium series elements in rock and soil.
- 1Natural mineral deposits
A result is read with its context
This is tracked through federal and state compliance monitoring in picocuries per liter (pCi/L). It is a screening measure, not the identity of a specific contaminant. PurityMap does not yet publish a per-system measured value for Gross alpha particles; this page is a reference explainer. To learn what is in your own water, check your utility’s Consumer Confidence Report (CCR) or use a certified home test.
- Above reference
- Evidence exceeds a reference level.
- Detected
- This substance was found in the monitoring record. Being present is not the same as being above a reference level, and this signal does not say which.
- Not detected
- Somebody looked and the laboratory reported nothing above its reporting limit. This is a result, and it is not the same as nobody looking.
- Not monitored
- No sampling for this substance has been reported for this system. Nothing is known either way, and an empty row is not a clean one.
12 cities with a health-based violation
A violation is a past event with a status, from the federal compliance record (EPA SDWIS, since 2016). It does not describe the water today.
- Inver Grove HeightsMinnesotaArchivedView city →
- Perth AmboyNew JerseyArchivedView city →
- RosemountMinnesotaArchivedView city →
- Box ElderSouth DakotaResolvedView city →
- BridgetonNew JerseyResolvedView city →
- AltoonaIowaArchivedView city →
- WindsorNew JerseyArchivedView city →
- Atascosa RuralTexasResolvedView city →
- WaukeshaWisconsinResolvedView city →
- South Saint PaulMinnesotaResolvedView city →
- SussexWisconsinResolvedView city →
- The PineryColoradoResolvedView city →
PurityMap does not yet publish a per-system measured value for gross alpha particles. Check your utility’s Consumer Confidence Report, or use a certified home test.
What can carry a gross alpha particles reduction claim
- Reverse osmosis
Semi-permeable membrane separation removing dissolved minerals, heavy metals, and persistent fluorinated chemicals down to 0.0001 microns.
- Ion exchange
Synthetic polyvalent resin beads that exchange unwanted dissolved ionic contaminants for harmless benchmark ions.
- Activated alumina
Boiling does not remove a dissolved chemical compound and can concentrate it. Many pitcher and refrigerator filters carry no verified claim for a compound like this at all.
A finding establishes the need, the need names the capability, the capability requires a verified certification. No product appears before that sequence completes. Filter Finder →
Frequently asked
Answers cite the same records as the page. How PurityMap analyzes water data
Gross alpha is a combined measure of alpha-particle radioactivity in water, a screening figure for naturally occurring radionuclides such as radium and polonium (excluding radon and uranium).
The enforceable federal limit is 15 pCi/L, excluding radon and uranium (MCL). The health-based goal (MCLG) is 0. PurityMap reads every measurement against its stated benchmark and never sets its own.
Natural mineral deposits.
Alpha-particle radiation above the limit increases long-term cancer risk. Gross alpha is used as a first screen; an exceedance typically prompts testing for the specific radionuclides behind it. The health goal is zero.
Treatment technologies commonly certified to reduce Gross alpha particles include Reverse osmosis, Ion exchange, Activated alumina. Match the exact certified claim to your water before buying. Holding a format is not the same as holding the claim.
In the federal compliance record (EPA SDWIS, since 2016), 12 cities in PurityMap's record across 7 states had a water system measure Gross alpha particles above the legal limit, most recently in 2026, including Inver Grove Heights, MN; Perth Amboy, NJ; Rosemount, MN. Each violation is a past event with a published status, not a description of the water today.