Combined Radium-226/228
radionuclide
Erosion of natural deposits; most common in groundwater.
EPA regulatory status
Legal limit (MCL)
5 pCi/L
Goal (MCLG)
0 pCi/L
MCL 5 pCi/L for combined radium-226 + radium-228 (the two isotopes are summed against a single limit). MCLG = 0.
Health effects
Long-term exposure is associated with an increased risk of cancer (radium is bone-seeking).
This is general public-health information, not medical advice — consult your physician with any health concerns.
National violations
44,563
EPA's enforcement data (SDWIS/ECHO) records 44,563 violations of Combined Radium-226/228's rule nationally.
How to remove Combined Radium-226/228
cation exchange
NSF/ANSI 44
Frequently asked questions
What is Combined Radium-226/228?
Combined Radium-226/228 is a radionuclide regulated in US drinking water. Erosion of natural deposits; most common in groundwater.
What is the legal limit for Combined Radium-226/228 in drinking water?
MCL 5 pCi/L for combined radium-226 + radium-228 (the two isotopes are summed against a single limit). MCLG = 0.
What health effects does Combined Radium-226/228 have?
Long-term exposure is associated with an increased risk of cancer (radium is bone-seeking).
How many violations of Combined Radium-226/228 limits are on record nationally?
EPA's enforcement data (SDWIS/ECHO) records 44,563 violations of Combined Radium-226/228's rule nationally.
How do I remove Combined Radium-226/228 from my water?
Filter technologies certified to reduce Combined Radium-226/228 include: cation exchange (NSF/ANSI 44), reverse osmosis (NSF/ANSI 58). Look for a filter independently certified against the specific NSF/ANSI standard for this contaminant — general "reduces contaminants" marketing claims are not the same as a contaminant-specific certification.
Source: EPA National Primary Drinking Water Regulations · Data as of 2026-07-16