Contaminant MCLG1
(mg/L)2
MCL or TT1
(mg/L)2
Potential Health Effects from Ingestion of Water Sources of Contaminant in Drinking Water


Disinfection Byproducts
Contaminant MCLG1
(mg/L)2
MCL or TT1
(mg/L)2
Potential Health Effects from Ingestion of Water Sources of Contaminant in Drinking Water
Bromate
zero
0.010

Increased risk of cancer

Byproduct of drinking water disinfection

Chlorite
0.8
1.0

Anemia; infants & young children: nervous system effects

Byproduct of drinking water disinfection

Haloacetic acids (HAA5)
n/a6
0.060

Increased risk of cancer

Byproduct of drinking water disinfection

Total Trihalomethanes (TTHMs)
none7
----------
n/a6
0.10
----------
0.080

Liver, kidney or central nervous system problems; increased risk of cancer

Byproduct of drinking water disinfection



Disinfectants
Contaminant MRDLG1
(mg/L)2
MRDL1
(mg/L)2
Potential Health Effects from Ingestion of Water Sources of Contaminant in Drinking Water


Inorganic Chemicals
Contaminant MCLG1
(mg/L)2
MCL or TT1
(mg/L)2
Potential Health Effects from Ingestion of Water Sources of Contaminant in Drinking Water


Organic Chemicals
Contaminant MCLG1
(mg/L)2
MCL or TT1
(mg/L)2
Potential Health Effects from Ingestion of Water
Sources of Contaminant in Drinking Water


Radionuclides

Contaminant MCLG1
(mg/L)2
MCL or TT1
(mg/L)2
Potential Health Effects from Ingestion of Water Sources of Contaminant in Drinking Water

1Definitions:
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 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 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.
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.
Treatment Technique - A required process intended to reduce the level of a contaminant in drinking water.2 Units are in milligrams per liter (mg/L) unless otherwise noted. Milligrams per liter are equivalent to parts per million.3 EPA's surface water treatment rules require systems using surface water or ground water under the direct influence of surface water to (1) disinfect their water, and (2) filter their water or meet criteria for avoiding filtration so that the following contaminants are controlled at the following levels:

4 more than 5.0% samples total coliform-positive in a month. (For water systems that collect fewer than 40 routine samples per month, no more than one sample can be total coliform-positive per month.) Every sample that has total coliform must be analyzed for either fecal coliforms or E. coli if two consecutive TC-positive samples, and one is also positive for E.coli fecal coliforms, system has an acute MCL violation. 5 Fecal coliform and E. coli are bacteria whose presence indicates that the water may be contaminated with human or animal wastes. Disease-causing microbes (pathogens) in these wastes can cause diarrhea, cramps, nausea, headaches, or other symptoms. These pathogens may pose a special health risk for infants, young children, and people with severely compromised immune systems. 6 Although there is no collective MCLG for this contaminant group, there are individual MCLGs for some of the individual contaminants:
7 MCLGs were not established before the 1986 Amendments to the Safe Drinking Water Act. Therefore, there is no MCLG for this contaminant.8 Lead and copper are regulated by a Treatment Technique that requires systems to control the corrosiveness of their water. If more than 10% of tap water samples exceed the action level, water systems must take additional steps. For copper, the action level is 1.3 mg/L, and for lead is 0.015 mg/L. 9 Each water system must certify, in writing, to the state (using third-party or manufacturer's certification) that when acrylamide and epichlorohydrin are used in drinking water systems, the combination (or product) of dose and monomer level does not exceed the levels specified, as follows:

Contaminant
Secondary Standard
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