EPA Designation Regulated
EPA Classification Inorganic Chemicals
EPA Levels 1,2 0.002 MCLG (mg/L)
0.002 MCLG (mg/L)
Alternative Names none
Sources Erosion of natural deposits; discharge from refineries and factories; runoff from landfills and croplands
Mercury is a metal from refinery and factory pollution, coal burning, landfill and agricultural runoff and erosion of natural deposits.


Mercury is a liquid metal found in natural deposits such as ores containing other elements.


Electrical products such as dry-cell batteries, fluorescent light bulbs, switches, and other control equipment account for 50 percent of mercury used.

Health Effects

Some people who drink water containing mercury well in excess of the maximum contaminant level (MCL) for many years could experience kidney damage.

EPA Data Source: Mercury

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.