Radionuclides
Radium (226 + 228) in Tap Water
Radium is a naturally occurring radioactive element that dissolves into groundwater from rock and soil. It is regulated as the combined activity of radium-226 and radium-228.
Substance identity
- Scientific name
- Combined radium-226 and radium-228
- Family
- Radionuclides
- CAS number
- Not published
This guide explains the compound. Only a water-system record or household test can tell you whether it appears in your water.
- Federal reference
- 5 pCi/L combined radium-226 + 228 (MCL)Enforceable maximum contaminant level
- Health-based goal
- 5 pCi/L combined federal limit (MCL); MCLG of 0US EPA Radionuclides Rule
- Measurement context
- Stated in the recordThis radionuclide is tracked through federal and state compliance monitoring, measured as picocuries per liter (pCi/L). Private wells in affected geology should be tested directly. PurityMap does not yet publish a per-system measured value for Radium (226 + 228); 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.
- Cities on record
- None yetUS cities in PurityMap's published record where Radium (226 + 228) appears
A reference is a published threshold, not a safety line drawn by PurityMap. Where a result sits against it is a finding; whether that constitutes a violation is a separately published compliance field.
What is Radium (226 + 228)?
Radium is a naturally occurring radioactive element that dissolves into groundwater from rock and soil. It is regulated as the combined activity of radium-226 and radium-228.
Where Radium (226 + 228) comes from
Natural radioactive decay of uranium and thorium in rock, dissolving into groundwater.
- Natural mineral deposits (granite, shale aquifers)
How Radium (226 + 228) is measured
This radionuclide is tracked through federal and state compliance monitoring, measured as picocuries per liter (pCi/L). Private wells in affected geology should be tested directly. PurityMap does not yet publish a per-system measured value for Radium (226 + 228); 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.
Why context mattersHow PurityMap reads a Radium (226 + 228) result
Evidence exceeds a reference level. Used sparingly and only when warranted.
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.
Somebody looked and the laboratory reported nothing above its reporting limit. This is a result, and it is not the same as nobody looking.
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.
Where the numbers come from
- A laboratory result for one sampling point
Collected under a monitoring programme, analysed by an approved method, and reported with its own detection limits.
- Read against a published reference
The reference comes from the regulator, with its own effective date. PurityMap does not set thresholds and does not adjust them.
- Attached to a system's Water Profile
Where it contributes to the published assessment alongside the evidence quality of the record it came from.
The full evidence chain →
Where Radium (226 + 228) is found across the U.S.
These are the places in PurityMap’s published record where Radium (226 + 228) appears on a water system’s monitoring results. It reflects the systems and sampling we track, not a national prevalence estimate.
PurityMap has no city on record with Radium (226 + 228) on its monitoring results yet. This fills in as monitoring data is published — a substance that was never tested is shown as pending, never as a pass.
Treatment capability, if a finding establishes a need
The formats that commonly hold a verified reduction claim for Radium (226 + 228) are Reverse osmosis, Ion exchange (softening), Activated alumina. Holding the format is not holding the claim — the certification record is what is checked.
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.
Whether a system-level measurement or a household-tap measurement is the relevant scope depends on how the compound enters the water — a published characteristic of the record, not an assumption drawn here.
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 questions
What is Radium (226 + 228)?
Radium is a naturally occurring radioactive element that dissolves into groundwater from rock and soil. It is regulated as the combined activity of radium-226 and radium-228.
What is the limit for Radium (226 + 228) in drinking water?
The enforceable federal limit is 5 pCi/L combined radium-226 + 228 (MCL). The health-based goal is 5 pCi/L combined federal limit (MCL); MCLG of 0. PurityMap reads every measurement against its stated benchmark and never sets its own.
Where does Radium (226 + 228) in tap water come from?
Natural mineral deposits (granite, shale aquifers).
Why does Radium (226 + 228) matter?
Long-term exposure to radium above the limit increases cancer risk, particularly bone cancer, because radium behaves like calcium and deposits in bone. As with other radionuclides the health goal is zero and the enforceable limit is set near the lowest feasible level.
How do you remove Radium (226 + 228) from water?
Treatment technologies commonly certified to reduce Radium (226 + 228) include Reverse osmosis, Ion exchange (softening), Activated alumina. Match the exact certified claim to your water before buying — holding a format is not the same as holding the claim.
Sources and methodology
Reference values on this page come from the governed contaminant record. Local occurrence claims stay on the linked water-system evidence pages, where sampling scope, period and source remain visible.
How PurityMap analyzes water data →