Thallium
metal
Leaching from ore-processing sites; discharge from electronics, glass, and drug factories.
EPA regulatory status
Legal limit (MCL)
0.002 mg/L
Goal (MCLG)
0.0005 mg/L
MCL 0.002 mg/L (2 ppb). MCLG = 0.0005 mg/L (0.5 ppb).
Health effects
Long-term exposure is associated with hair loss, changes in blood, and kidney, intestine, or liver problems.
This is general public-health information, not medical advice — consult your physician with any health concerns.
National violations
19,766
EPA's enforcement data (SDWIS/ECHO) records 19,766 violations of Thallium's rule nationally.
How to remove Thallium
distillation
NSF/ANSI 62
Frequently asked questions
What is Thallium?
Thallium is a metal regulated in US drinking water. Leaching from ore-processing sites; discharge from electronics, glass, and drug factories.
What is the legal limit for Thallium in drinking water?
MCL 0.002 mg/L (2 ppb). MCLG = 0.0005 mg/L (0.5 ppb).
What health effects does Thallium have?
Long-term exposure is associated with hair loss, changes in blood, and kidney, intestine, or liver problems.
How many violations of Thallium limits are on record nationally?
EPA's enforcement data (SDWIS/ECHO) records 19,766 violations of Thallium's rule nationally.
How do I remove Thallium from my water?
Filter technologies certified to reduce Thallium include: reverse osmosis (NSF/ANSI 58), distillation (NSF/ANSI 62). 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