EPA Designation Regulated
EPA Classification Inorganic Chemicals
EPA Levels 1,2 0.2 MCLG (mg/L)
0.2 MCLG (mg/L)
Alternative Names none
Sources Discharge from steel/metal factories; discharge from plastic and fertilizer factories
Cyanide is a chemical used in mining and steel/metal, plastic, and pesticide manufacturing; it is applied to roads as road salts, and small quantities occur naturally in some plants.


Cyanide is a carbon-nitrogen chemical unit which combines with many organic and inorganic compounds.


The most commonly used form, hydrogen cyanide, is mainly used to make compounds and other synthetic fibers and resins.

Health Effects

Some people who drink water containing cyanide well in excess of the maximum contaminant level (MCL) for many years could experience nerve damage or problems with their thyroid.

EPA Data Source: Cyanide

EPA Definitions:

1Maximum Contaminant Level Goal (MCLG) - The level of a contaminant in drinking water below which there is no known or expected risk to health. MCLGs allow for a margin of safety and are non-enforceable public health goals.

Maximum Contaminant Level (MCL) - The highest level of a contaminant that is allowed in drinking water. MCLs are set as close to MCLGs as feasible using the best available treatment technology and taking cost into consideration. MCLs are enforceable standards.

Maximum Residual Disinfectant Level Goal (MRDLG) - The level of a drinking water disinfectant below which there is no known or expected risk to health. MRDLGs do not reflect the benefits of the use of disinfectants to control microbial contaminants.

(TT) Treatment Technique - A required process intended to reduce the level of a contaminant in drinking water.

Maximum Residual Disinfectant Level (MRDL) - The highest level of a disinfectant allowed in drinking water. There is convincing evidence that addition of a disinfectant is necessary for control of microbial contaminants.

2 Units are in milligrams per liter (mg/L) unless otherwise noted. Milligrams per liter are equivalent to parts per million.