EPA Water Quality Standards
Understanding Maximum Contaminant Levels (MCL) and EPA MCLG for drinking water contaminants regulated by the EPA
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Regulated Contaminants
MCL
Maximum Contaminant Level
SDWA
Safe Drinking Water Act
Understanding the Standards
EPA Maximum Contaminant Level (MCL)
The highest level of a contaminant that is allowed in drinking water. MCLs are legally enforceable standards set by the EPA under the Safe Drinking Water Act.
Maximum Contaminant Level Goal (MCLG)
Non-enforceable health goals set by the EPA at levels where no known or anticipated adverse health effects occur, allowing for a margin of safety. MCLGs consider only health risks and do not factor in cost or technological feasibility.
Important Note
Legal does not always mean safe. MCLGs represent health goals, but actual enforceable limits (MCLs) may be higher due to cost and technological constraints. Some health advocates recommend even stricter limits based on the latest research.
Contaminants by Category
Disinfectants
Chemicals added to kill harmful microorganisms
Chloramine
EPA Limit (MCL)
4000 ppb
Health Goal (MCLG)
4000 ppb
Chlorine Dioxide
EPA Limit (MCL)
800 ppb
Health Goal (MCLG)
800 ppb
Disinfection Byproducts
Chemicals formed when disinfectants react with organic matter in water
Bromate
EPA Limit (MCL)
10 ppb
Health Goal (MCLG)
0 ppb
MCL is Infinityx higher than health goal
Chlorite
EPA Limit (MCL)
1000 ppb
Health Goal (MCLG)
800 ppb
MCL is 1.3x higher than health goal
Total Haloacetic Acids (HAA5)
EPA Limit (MCL)
60 ppb
Total THMs
EPA Limit (MCL)
80 ppb
Inorganic Compounds
Non-carbon-based chemical compounds
Antimony
EPA Limit (MCL)
6 ppb
Health Goal (MCLG)
6 ppb
Arsenic
EPA Limit (MCL)
10 ppb
Health Goal (MCLG)
0 ppb
MCL is Infinityx higher than health goal
Asbestos
EPA Limit (MCL)
7 MFL
Health Goal (MCLG)
7 MFL
Barium
EPA Limit (MCL)
2000 ppb
Health Goal (MCLG)
2000 ppb
Beryllium
EPA Limit (MCL)
4 ppb
Health Goal (MCLG)
4 ppb
Cadmium
EPA Limit (MCL)
5 ppb
Health Goal (MCLG)
5 ppb
Chromium (Total)
EPA Limit (MCL)
100 ppb
Health Goal (MCLG)
100 ppb
Copper
EPA Limit (MCL)
1300 ppb
Health Goal (MCLG)
1300 ppb
Cyanide
EPA Limit (MCL)
200 ppb
Health Goal (MCLG)
200 ppb
Fluoride
EPA Limit (MCL)
4000 ppb
Health Goal (MCLG)
4000 ppb
Lead
EPA Limit (MCL)
10 ppb
Health Goal (MCLG)
0 ppb
MCL is Infinityx higher than health goal
Mercury
EPA Limit (MCL)
2 ppb
Health Goal (MCLG)
2 ppb
Nitrate (as N)
EPA Limit (MCL)
10000 ppb
Health Goal (MCLG)
10000 ppb
Nitrite (as N)
EPA Limit (MCL)
1000 ppb
Health Goal (MCLG)
1000 ppb
Selenium
EPA Limit (MCL)
50 ppb
Health Goal (MCLG)
50 ppb
Thallium
EPA Limit (MCL)
2 ppb
Health Goal (MCLG)
0.5 ppb
MCL is 4x higher than health goal
Microorganisms
Biological organisms that can cause illness
Cryptosporidium
EPA Limit (MCL)
TT
Health Goal (MCLG)
0 N/A
Total Coliforms
EPA Limit (MCL)
5 %
Health Goal (MCLG)
0 %
MCL is Infinityx higher than health goal
Turbidity
EPA Limit (MCL)
TT
organic-chemicals---socs
2,4-D
EPA Limit (MCL)
70 ppb
Health Goal (MCLG)
70 ppb
Alachlor
EPA Limit (MCL)
2 ppb
Health Goal (MCLG)
0 ppb
MCL is Infinityx higher than health goal
Atrazine
EPA Limit (MCL)
3 ppb
Health Goal (MCLG)
3 ppb
Benzo(a)pyrene
EPA Limit (MCL)
0.2 ppb
Health Goal (MCLG)
0 ppb
MCL is Infinityx higher than health goal
Carbofuran
EPA Limit (MCL)
40 ppb
Health Goal (MCLG)
40 ppb
Dalapon
EPA Limit (MCL)
200 ppb
Health Goal (MCLG)
200 ppb
Glyphosate
EPA Limit (MCL)
700 ppb
Health Goal (MCLG)
700 ppb
Hexachlorobenzene
EPA Limit (MCL)
1 ppb
Health Goal (MCLG)
0 ppb
MCL is Infinityx higher than health goal
Hexachlorocyclopentadiene
EPA Limit (MCL)
50 ppb
Health Goal (MCLG)
50 ppb
Pentachlorophenol
EPA Limit (MCL)
1 ppb
Health Goal (MCLG)
0 ppb
MCL is Infinityx higher than health goal
Simazine
EPA Limit (MCL)
4 ppb
Health Goal (MCLG)
4 ppb
Toxaphene
EPA Limit (MCL)
3 ppb
Health Goal (MCLG)
0 ppb
MCL is Infinityx higher than health goal
organic-chemicals---vocs
1,1,1 Trichloroethane
EPA Limit (MCL)
200 ppb
Health Goal (MCLG)
200 ppb
1,1,2 Trichloroethane
EPA Limit (MCL)
5 ppb
Health Goal (MCLG)
3 ppb
MCL is 1.7x higher than health goal
1,2 Dichlorobenzene
EPA Limit (MCL)
600 ppb
Health Goal (MCLG)
600 ppb
1,2 Dichloroethane
EPA Limit (MCL)
5 ppb
Health Goal (MCLG)
0 ppb
MCL is Infinityx higher than health goal
1,2 Dichloropropane
EPA Limit (MCL)
5 ppb
Health Goal (MCLG)
0 ppb
MCL is Infinityx higher than health goal
1,2,4 Trichlorobenzene
EPA Limit (MCL)
70 ppb
Health Goal (MCLG)
70 ppb
1,4 Dichlorobenzene
EPA Limit (MCL)
75 ppb
Health Goal (MCLG)
75 ppb
Benzene
EPA Limit (MCL)
5 ppb
Health Goal (MCLG)
0 ppb
MCL is Infinityx higher than health goal
Carbon Tetrachloride
EPA Limit (MCL)
5 ppb
Health Goal (MCLG)
0 ppb
MCL is Infinityx higher than health goal
Chlorobenzene
EPA Limit (MCL)
100 ppb
Health Goal (MCLG)
100 ppb
Dichloromethane
EPA Limit (MCL)
5 ppb
Health Goal (MCLG)
0 ppb
MCL is Infinityx higher than health goal
Ethylbenzene
EPA Limit (MCL)
700 ppb
Health Goal (MCLG)
700 ppb
Styrene
EPA Limit (MCL)
100 ppb
Health Goal (MCLG)
100 ppb
Tetrachloroethylene
EPA Limit (MCL)
5 ppb
Health Goal (MCLG)
0 ppb
MCL is Infinityx higher than health goal
Trichloroethylene
EPA Limit (MCL)
5 ppb
Health Goal (MCLG)
0 ppb
MCL is Infinityx higher than health goal
Vinyl Chloride
EPA Limit (MCL)
2 ppb
Health Goal (MCLG)
0 ppb
MCL is Infinityx higher than health goal
Xylenes (Total)
EPA Limit (MCL)
10000 ppb
Health Goal (MCLG)
10000 ppb
PFAS
Per- and polyfluoroalkyl substances, known as 'forever chemicals'
GenX
EPA Limit (MCL)
0.01 ppb
Health Goal (MCLG)
0.01 ppb
Perfluorooctanesulfonic acid
EPA Limit (MCL)
0.004 ppb
Health Goal (MCLG)
0 ppb
MCL is Infinityx higher than health goal
Perfluorooctanoic acid
EPA Limit (MCL)
0.004 ppb
Health Goal (MCLG)
0 ppb
MCL is Infinityx higher than health goal
Radiological
Radioactive substances
Gross Alpha Activity
EPA Limit (MCL)
15 pCi/L
Health Goal (MCLG)
0 pCi/L
MCL is Infinityx higher than health goal
Radium, combined (-226 & -228)
EPA Limit (MCL)
5 pCi/L
Health Goal (MCLG)
0 pCi/L
MCL is Infinityx higher than health goal
Uranium
EPA Limit (MCL)
30 ug/L
Health Goal (MCLG)
0 ug/L
MCL is Infinityx higher than health goal
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