Drinking Water Standards

National Primary Drinking Water Standards

Contaminants MCL or TT1 (mg/L)2 Potential Health Effects from Exposure Above the MCL Common Sources of Contaminant in Drinking Water Public Health Goal
Acrylamide TT8 Nervous system or blood problems Added to water during sewage/wastewater increased risk of cancer treatment zero
Alachlor 0.002 Eye, liver, kidney or spleen problems; anemia; increased risk of cancer Runoff from herbicide used on row crops zero
Alpha particles 15 picocuries per Liter (pCi/L) Increased risk of cancer Erosion of natural deposits of certain minerals that are radioactive and may emit a form of radiation known as alpha radiation zero
Arsenic 0.010 as of 1/23/06 Skin damage or problems with circulatory systems, and may have increased risk of getting cancer Erosion of natural deposits; runoff from orchards, runoff from glass & electronics production wastes 0
Asbestos (fibers >10 micrometers) 7 million fibers per Liter (MFL) Increased risk of developing benign intestinal polyps Decay of asbestos cement in water mains; erosion of natural deposits 7 MFL
Atrazine 0.003 Cardiovascular system or reproductive problems Runoff from herbicide used on row crops 0.003
Barium 2 Increase in blood pressure Discharge of drilling wastes; discharge from metal refineries; erosion of natural deposits 2
Benzene 0.005 Anemia; decrease in blook platelets; increased risk of cancer Discharge from factories; leaching from gas storage tanks and landfills zero
Benzo(a)pyrene (PAHs) 0.0002 Reproductive difficulties; increased risk of cancer Leaching from linings of water storage tanks and distribution lines zero
Beryllium 0.004 Intestinal lesions Discharge from metal refineries and coal-burning factories; discharge from electrical, aerospace, and defense industries 0.004
Beta particles and photon emitters 4 millirems per year Increased risk of cancer Decay of natural and man-made deposits of certain minerals that are radioactive and may emit forms of radiation known as photons and beta radiation zero
Bromate 0.010 Increased risk of cancer Byproduct of drinking water disinfection zero
Cadmium 0.005 Kidney damage Corrosion of galvanized pipes; erosion of natural deposits; discharge from metal refineries; runoff from waste batteries and paints 0.005
Carbofuran 0.04 Problems with blood, nervous system, or reproductive system Leaching of soil fumigant used on rice and alfalfa 0.04
Carbon tetrachloride 0.005 Liver problems; increased risk of cancer Discharge from chemical plants and other industrial activities zero
Chloramines (as Cl2) MRDL=4.01 Eye/nose irritation; stomach discomfort, anemia Water additive used to control microbes MRDLG = 4
Chlordane 0.002 Liver or nervous system problems; increased risk of cancer Residue of banned termiticide zero
Chlorine (as Cl2) MRDL=4.01 Eye/nose irritation; stomach discomfort Water additive used to control microbes MRDLG = 41
Chlorine dioxide (as ClO2) MRDL=0.81 Anemia; infants & young children: nervous system effects Water additive used to control microbes MRDLG = 0.81
Chlorite 1.0 Anemia; infants & young children: nervous system effects Byproduct of drinking water disinfection 0.8
Chlorobenzene 0.1 Liver or kidney problems Discharge from chemical and agricultural chemical factories 0.1
Chromium (total) 0.1 Allergic dermatitis Discharge from steel and pulp mills; erosion of natural deposits 0.1
Copper TT7; Action Level = 1.3 Short term exposure: Gastrointestinal distress. Long term exposure: Liver or kidney damage. People with Wilson’s Disease should consult their personal doctor if the amount of copper in their water exceeds the action level Corrosion of household plumbing systems; erosion of natural deposits 1.3
Cryptosporidium TT3 Gastrointestinal illness (e.g., diarrhea, vomiting, cramps) Human and animal fecal waste zero
Cyanide (as free cyanide) 0.2 Nerve damage or thyroid problems Discharge from steel/metal factories; discharge from plastic and fertilizer factories 0.2
2, 4-D 0.07 Kidney, liver, or adrenal gland problems Runoff from herbicide used on row crops 0.07
Dalapon 0.2 Minor kidney changes Runoff from herbicide used on rights of way 0.2
1,2-Dibromo-3-chloropropane (DBCP) 0.0002 Reproductive difficulties; increased risk of cancer Runoff/leaching from soil fumigant used on soybeans, cotton, pineapples, and orchards zero
o-Dichlorobenzene 0.6 Liver, kidney, or circulatory system problems Discharge from industrial chemical factories 0.6
p-Dichlorobenzene 0.075 Anemia; liver, kidney or spleen damage; changes in blood Discharge from industrial chemical factories 0.075
1,2-Dichloroethane 0.005 Increased risk of cancer Discharge from industrial chemical factories zero
1,1-Dichloroethylene 0.007 Liver problems Discharge from industrial chemical factories 0.007
cis-1,2-Dichloroethylene 0.07 Liver problems Discharge from industrial chemical factories 0.07
trans-1,2-Dichloroethylene 0.1 Liver problems Discharge from industrial chemical factories 0.1
Dichloromethane 0.005 Liver problems; increased risk of cancer Discharge from drug and chemical factories zero
1,2-Dichloropropane 0.005 Increased risk of cancer Discharge from industrial chemical factories zero
Di(2-ethylhexyl) adipate 0.4 Weight loss, live problems, or possible reproductive difficulties Discharge from chemical factories 0.4
Di(2-ethylhexyl) phthalate 0.006 Reproductive difficulties; liver problems; increased risk of cancer Discharge from rubber and chemical factories zero
Dinoseb 0.007 Reproductive difficulties Runoff from herbicide used on soybeans and vegetables 0.007
Dioxin (2,3,7,8-TCDD) 0.00000003 Reproductive difficulties; increased risk of cancer Emissions from waste incineration and other combustion; discharge from chemical factories zero
Diquat 0.02 Cataracts Runoff from herbicide use 0.02
Endothall 0.1 Stomach and intestinal problems Runoff from herbicide use 0.1
Endrin 0.002 Liver problems Residue of banned insecticide 0.002
Epichlorohydrin TT8 Increased cancer risk, and over a long period of time, stomach problems Discharge from industrial chemical factories; an impurity of some water treatment chemicals zero
Ethylbenzene 0.7 Liver or kidneys problems Discharge from petroleum refineries 0.7
Ethylene dibromide 0.00005 Problems with liver, stomach, reproductive system, or kidneys; increased risk of cancer Discharge from petroleum refineries zero
Fluoride 4.0 Bone disease (pain and tenderness of the bones); Children may get mottled teeth Water additive which promotes strong teeth; erosion of natural deposits; discharge from fertilizer and aluminum factories 4.0
Giardia lamblia TT3 Gastrointestinal illness (e.g., diarrhea, vomiting, cramps) Human and animal fecal waste zero
Glyphosate 0.7 Kidney problems; reproductive difficulties Runoff from herbicide use 0.7
Haloacetic acids (HAA5) 0.060 Increased risk of cancer Byproduct of drinking water disinfection n/a 6
Heptachlor 0.0004 Liver damage; increased risk of cancer Residue of banned termiticide zero
Heptachlor epoxide 0.0002 Liver damage; increased risk of cancer Breakdown of heptachlor zero
Heterotrophic plate count (HPC) TT3 HPC has no health effects; it is an analytic method used to measure the variety of bacteria that are common in water. The lower the concentration of bacteria in drinking water, the better maintained the water system is. HPC measures a range of bacteria that are naturally present in the environment n/a
Hexachlorobenzene 0.001 Liver or kidney problems; reproductive difficulties; increased risk of cancer Discharge from metal refineries and agricultural chemical factories zero
Hexachlorocyclopentadiene 0.05 Kidney or stomach problems Discharge from chemical factories 0.05
Lead TT7; Action Level = 0.015 Infants and children: Delays in physical or mental development; children could show slight deficits in attention span and learning abilities; Adults: Kidney problems; high blood pressure Corrosion of household plumbing systems; erosion of natural deposits zero
Legionella TT3 Legionnaire’s Disease, a type of pneumonia Found naturally in water; multiplies in heating systems zero
Lindane 0.0002 Liver or kidney problems Runoff/leaching from insecticide used on cattle, lumber, gardens 0.0002
Mercury (inorganic) 0.002 Kidney damage Erosion of natural deposits; discharge from refineries and factories; runoff from landfills and croplands 0.002
Methoxychlor 0.04 Reproductive difficulties Runoff/leaching from insecticide used on fruits, vegetables, alfalfa, livestock 0.04
Nitrate (measured as Nitrogen) 10 Infants below the age of six months who drink water containing nitrate in excess of the MCL could become seriously ill and, if untreated, may die. Symptoms include shortness of breath and blue-baby syndrome. Runoff from fertilizer use; leaching from septic tanks, sewage; erosion of natural deposits 10
Nitrite (measured as Nitrogen) 1 Infants below the age of six months who drink water containing nitrite in excess of the MCL could become seriously ill and, if untreated, may die. Symptoms include shortness of breath and blue-baby syndrome. Runoff from fertilizer use; leaching from septic tanks, sewage; erosion of natural deposits 1
Oxamyl (Vydate) 0.2 Slight nervous system effects Runoff/leaching from insecticide used on apples, potatoes, and tomatoes 0.2
Pentachlorophenol 0.001 LIver or kidney problems; increased cancer risk Discharge from wood preserving factories zero
Picloram 0.5 Liver problems Herbicide runoff 0.5
Polychlorinated biphenyls (PCBs) 0.0005 Skin changes; thymus gland problems; immune deficiencies; reproductive or nervous system difficulties; increased risk of cancer Runoff from landfills; discharge of waste chemicals zero
Radium 226 and Radium 228 (combined) 5 pCi/L Increased risk of cancer Erosion of natural deposits zero
Selenium 0.05 Hair or fingernail loss; numbness in fingers or toes; circulatory problems Discharge from petroleum refineries; erosion of natural deposits; discharge from mines 0.05
Simazine 0.004 Problems with blood Herbicide runoff 0.004
Styrene 0.1 Liver, kidney, or circulatory system problems Discharge from rubber and plastic factories; leaching from landfills 0.1
Tetrachloroethylene 0.005 Liver problems; increased risk of cancer Discharge from factories and dry cleaners zero
Thallium 0.002 Hair loss; changes in blood; kidney, intestine, or liver problems Leaching from ore-processing sites; discharge from electronics, glass, and drug factories 0.0005
Toluene 1 Nervous system, kidney, or liver problems Discharge from petroleum factories 1
Total Coliforms (including fecal coliform and E. coli) 5.0% 4 Not a health threat in itself; it is used to indicate whether other potentially harmful bacteria may be present5 Coliforms are naturally present in the environment as well as feces; fecal coliforms and E. coli only come from human and animal fecal waste zero
Total Trihalomethanes (TTHMs) 0.10
0.080 after 12/31/03		 Liver, kidney or central nervous system problems; increased risk of cancer Byproduct of drinking water disinfection n/a6
Toxaphene 0.003 Kidney, liver, or thyroid problems; increased risk of cancer Runoff/leaching from insecticide used on cotton and cattle zero
2,4,5-TP (Silvex) 0.05 Liver problems Residue of banned herbicide 0.05
1,2,4-Trichlorobenzene 0.07 Changes in adrenal glands Discharge from textile finishing factories 0.07
1,1,1-Trichloroethane 0.2 Liver, nervous system, or circulatory problems Discharge from metal degreasing sites and other factories 0.2
1,1,2-Trichloroethane 0.005 Liver, kidney, or immune system problems Discharge from industrial chemical factories 0.003
Trichloroethylene 0.005 Liver problems; increased risk of cancer Discharge from metal degreasing sites and other factories zero
Turbidity TT3 Turbidity is a measure of the cloudiness of water. It is used to indicate water quality and filtration effectiveness (e.g., whether disease-causing organisms are present). Higher turbidity levels are often associated with higher levels of disease-causing micro-organisms such as viruses, parasites and some bacteria. These organisms can cause symptoms such as nausea, cramps, diarrhea, and associated headaches. Soil runoff n/a
Uranium 30 ug/L as of 12/08/03 Increased risk of cancer, kidney toxicity Erosion of natural deposits zero
Vinyl chloride 0.002 Increased risk of cancer Leaching from PVC pipes; discharge from plastic factories zero
Viruses (enteric) TT3 Gastrointestinal illness (e.g., diarrhea, vomiting, cramps) Human and animal fecal waste zero
Xylenes (total) 10 Nervous system damage Discharge from petroleum factories; discharge from chemical factories 10
 
NOTES
1 Definitions
• 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 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.
• 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.
• Treatment Technique (TT)—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 (ppm).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:
• Cryptosporidium (as of 1/1/02 for systems serving >10,000 and 1/14/05 for systems serving <10,000) 99% removal.
• Giardia lamblia: 99.9% removal/inactivation
• Viruses: 99.99% removal/inactivation
• Legionella: No limit, but EPA believes that if Giardia and viruses are removed/inactivated, Legionella will also be controlled.
• Turbidity: At no time can turbidity (cloudiness of water) go above 5 nephelolometric turbidity units (NTU); systems that filter must ensure that the turbidity go no higher than 1 NTU (0.5 NTU for conventional or direct filtration) in at least 95% of the daily samples in any month. As of January 1, 2002, for systems servicing >10,000, and January 14, 2005, for systems servicing <10,000, turbidity may never exceed 1 NTU, and must not exceed 0.3 NTU in 95% of daily samples in any month.
• HPC: No more than 500 bacterial colonies per milliliter
• Long Term 1 Enhanced Surface Water Treatment (Effective Date: January 14, 2005); Surface water systems or (GWUDI) systems serving fewer than 10,000 people must comply with the applicable Long Term 1 Enhanced Surface Water Treatment Rule provisions (e.g. turbidity standards, individual filter monitoring, Cryptosporidium removal requirements, updated watershed control requirements for unfiltered systems).
• Filter Backwash Recycling: The Filter Backwash Recycling Rule requires systems that recycle to return specific recycle flows through all processes of the system’s existing conventional or direct filtration system or at an alternate location approved by the state.

4 No 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:
• Haloacetic acids: dichloroacetic acid (zero); trichloroacetic acid (0.3 mg/L)
• Trihalomethanes: bromodichloromethane (zero); bromoform (zero); dibromochloromethane (0.06 mg/L)

7 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.

8 Each water system must certify, in writing, to the state (using third-party or manufacturers certification) that when it uses acrylamide and/or epichlorohydrin to treat water, the combination (or product) of dose and monomer level does not exceed the levels specified, as follows: Acrylamide = 0.05% dosed at 1 mg/L (or equivalent); Epichlorohydrin = 0.01% dosed at 20 mg/L (or equivalent).

National Secondary Drinking Water Standards

National Secondary Drinking Water Standards are non-enforceable guidelines regulating contaminants that may cause cosmetic effects (such as skin or tooth discoloration) or aesthetic effects (such as taste, odor, or color) in drinking water. EPA recommends secondary standards to water systems but does not require systems to comply. However, states may choose to adopt them as enforceable standards.

Contaminants Secondary Standard
Aluminum 0.05 to 0.2 mg/L
Chloride 250 mg/L
Color 15 (color units)
Copper 1.0 mg/L
Corrosivity noncorrosive
Fluoride 2.0 mg/L
Foaming Agents 0.5 mg/L
Iron 0.3 mg/L
Manganese 0.05 mg/L
Odor 3 threshold odor number
pH 6.5-8.5
Silver 0.10 mg/L
Sulfate 250 mg/L
Total Dissolved Solids 500 mg/L
Zinc 5 mg/L