Cyanide
inorganic chemical
Discharge from steel/metal factories; discharge from plastic and fertilizer factories.
EPA regulatory status
Legal limit (MCL)
0.2 mg/L
Goal (MCLG)
0.2 mg/L
MCL 0.2 mg/L (200 ppb). MCLG = 0.2 mg/L.
Health effects
Long-term exposure is associated with nerve damage or thyroid problems.
This is general public-health information, not medical advice — consult your physician with any health concerns.
National violations
16,116
EPA's enforcement data (SDWIS/ECHO) records 16,116 violations of Cyanide's rule nationally.
How to remove Cyanide
Frequently asked questions
What is Cyanide?
Cyanide is a inorganic chemical regulated in US drinking water. Discharge from steel/metal factories; discharge from plastic and fertilizer factories.
What is the legal limit for Cyanide in drinking water?
MCL 0.2 mg/L (200 ppb). MCLG = 0.2 mg/L.
What health effects does Cyanide have?
Long-term exposure is associated with nerve damage or thyroid problems.
How many violations of Cyanide limits are on record nationally?
EPA's enforcement data (SDWIS/ECHO) records 16,116 violations of Cyanide's rule nationally.
How do I remove Cyanide from my water?
Filter technologies certified to reduce Cyanide include: 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