U.S. Environmental Protection Agency's Office of Water Office of Ground Water and Drinking Water
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Current Drinking Water Standards

National Primary and Secondary Drinking Water Regulations

National Primary Drinking Water Regulations (NPDWRs or primary standards) are legally enforceable standards that apply to public water systems. Primary standards protect drinking water quality by limiting the levels of specific contaminants that can adversely affect public health and are known or anticipated to occur in public water systems. Table 1 divides these contaminants into Inorganic Chemicals, Organic Chemicals, Radionuclides, and Microorganisms. See Setting Standards for Safe Drinking Water to learn about EPA's standard-setting process.

National Primary Drinking Water Regulations

Contaminants MCLG1
(mg/L)4		 MCL2 or TT3
(mg/L)4		 Potential Health Effects from Ingestion of Water Sources of Contaminant in Drinking Water
Inorganic Chemicals
Antimony 0.006 0.006 Increase in blood cholesterol; decrease in blood glucose Discharge from petroleum refineries; fire retardants; ceramics; electronics; solder
Arsenic none5 0.05 Skin damage; circulatory system problems; increased risk of cancer Discharge from semiconductor manufacturing; petroleum refining; wood preservatives; animal feed additives; herbicides; erosion of natural deposits
Asbestos
(fiber >10 micrometers)		 7 million fibers per Liter 7 MFL Increased risk of developing benign intestinal polyps Decay of asbestos cement in water mains; erosion of natural deposits
Barium 2 2 Increase in blood pressure Discharge of drilling wastes; discharge from metal refineries; erosion of natural deposits
Beryllium 0.004 0.004 Intestinal lesions Discharge from metal refineries and coal-burning factories; discharge from electrical, aerospace, and defense industries
Cadmium 0.005 0.005 Kidney damage Corrosion of galvanized pipes; erosion of natural deposits; discharge from metal refineries; runoff from waste batteries and paints
Chromium (total) 0.1 0.1 Some people who use water containing chromium well in excess of the MCL over many years could experience allergic dermatitis Discharge from steel and pulp mills; erosion of natural deposits
Copper 1.3 Action Level=1.3; TT6 Short term exposure: Gastrointestinal distress.
Long term exposure: Liver or kidney damage. Those with Wilson's Disease should consult their personal doctor if their water systems exceed the copper action level. 		Corrosion of household plumbing systems; erosion of natural deposits; leaching from wood preservatives
Cyanide (as free cyanide) 0.2 0.2 Nerve damage or thyroid problems Discharge from steel/metal factories; discharge from plastic and fertilizer factories
Fluoride 4.0 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
Lead zero Action Level=0.015; TT6 Infants and children: Delays in physical or mental development.
Adults: Kidney problems; high blood pressure 		Corrosion of household plumbing systems; erosion of natural deposits
Inorganic Mercury 0.002 0.002 Kidney damage Erosion of natural deposits; discharge from refineries and factories; runoff from landfills and cropland
Nitrate (measured as Nitrogen) 10 10 "Blue baby syndrome" in infants under six months - life threatening without immediate medical attention.
Symptoms: Infant looks blue and has shortness of breath. 		Runoff from fertilizer use; leaching from septic tanks, sewage; erosion of natural deposits
Nitrite (measured as Nitrogen) 1 1 "Blue baby syndrome" in infants under six months - life threatening without immediate medical attention.
Symptoms: Infant looks blue and has shortness of breath. 		Runoff from fertilizer use; leaching from septic tanks, sewage; erosion of natural deposits
Selenium 0.05 0.05 Hair or fingernail loss; numbness in fingers or toes; circulatory problems Discharge from petroleum refineries; erosion of natural deposits; discharge from mines
Thallium 0.0005 0.002 Hair loss; changes in blood; kidney, intestine, or liver problems Leaching from ore-processing sites; discharge from electronics, glass, and pharmaceutical companies
Organic Chemicals
Acrylamide zero TT7 Nervous system or blood problems; increased risk of cancer Added to water during sewage/wastewater treatment
Alachlor zero 0.002 Eye, liver, kidney or spleen problems; anemia; increased risk of cancer Runoff from herbicide used on row crops
Atrazine 0.003 0.003 Cardiovascular system problems; reproductive difficulties Runoff from herbicide used on row crops
Benzene zero 0.005 Anemia; decrease in blood platelets; increased risk of cancer Discharge from factories; leaching from gas storage tanks and landfills
Benzo(a)pyrene zero 0.0002 Reproductive difficulties; increased risk of cancer Leaching from linings of water storage tanks and distribution lines
Carbofuran 0.04 0.04 Problems with blood or nervous system; reproductive difficulties. Leaching of soil fumigant used on rice and alfalfa
Carbon tetrachloride zero .005 Liver problems; increased risk of cancer Discharge from chemical plants and other industrial activities
Chlordane zero 0.002 Liver or nervous system problems; increased risk of cancer Residue of banned termiticide
Chlorobenzene 0.1 0.1 Liver or kidney problems Discharger from chemical and agricultural chemical factories
2,4-D 0.07 0.07 Kidney, liver, or adrenal gland problems Runoff from herbicide used on row crops
Dalapon 0.2 0.2 Minor kidney changes Runoff from herbicide used on rights of way
1,2-Dibromo-3-chloropropane (DBCP) zero 0.0002 Reproductive difficulties; increased risk of cancer Runoff/leaching from soil fumigant used on soybeans, cotton, pineapples, and orchards
o-Dichlorobenzene 0.6 0.6 Liver, kidney, or circulatory system problems Discharge from industrial chemical factories
p-Dichlorobenzene 0.075 0.075 Anemia; liver, kidney or spleen damage; changes in blood Discharge from industrial chemical factories
1,2-Dichloroethane zero 0.005 Increased risk of cancer Discharge from industrial chemical factories
1-1-Dichloroethylene 0.007 0.007 Liver problems Discharge from industrial chemical factories
cis-1, 2-Dichloroethylene 0.07 0.07 Liver problems Discharge from industrial chemical factories
trans-1,2-Dichloroethylene 0.1 0.1 Liver problems Discharge from industrial chemical factories
Dichloromethane zero 0.005 Liver problems; increased risk of cancer Discharge from pharmaceutical and chemical factories
1-2-Dichloropropane zero 0.005 Increased risk of cancer Discharge from industrial chemical factories
Di(2-ethylhexyl)adipate 0.4 0.4 General toxic effects or reproductive difficulties Leaching from PVC plumbing systems; discharge from chemical factories
Di(2-ethylhexyl)phthalate zero 0.006 Reproductive difficulties; liver problems; increased risk of cancer Discharge from rubber and chemical factories
Dinoseb 0.007 0.007 Reproductive difficulties Runoff from herbicide used on soybeans and vegetables
Dioxin (2,3,7,8-TCDD) zero 0.00000003 Reproductive difficulties; increased risk of cancer Emissions from waste incineration and other combustion; discharge from chemical factories
Diquat 0.02 0.02 Cataracts Runoff from herbicide use
Endothall 0.1 0.1 Stomach and intestinal problems Runoff from herbicide use
Endrin 0.002 0.002 Nervous system effects Residue of banned insecticide
Epichlorohydrin zero TT7 Stomach problems; reproductive difficulties; increased risk of cancer Discharge from industrial chemical factories; added to water during treatment process
Ethylbenzene 0.7 0.7 Liver or kidney problems Discharge from petroleum refineries
Ethelyne dibromide zero 0.00005 Stomach problems; reproductive difficulties; increased risk of cancer Discharge from petroleum refineries
Glyphosate 0.7 0.7 Kidney problems; reproductive difficulties Runoff from herbicide use
Heptachlor zero 0.0004 Liver damage; increased risk of cancer Residue of banned termiticide
Heptachlor epoxide zero 0.0002 Liver damage; increased risk of cancer Breakdown of hepatachlor
Hexachlorobenzene zero 0.001 Liver or kidney problems; reproductive difficulties; increased risk of cancer Discharge from metal refineries and agricultural chemical factories
Hexachlorocyclopentadiene 0.05 0.05 Kidney or stomach problems Discharge from chemical factories
Lindane 0.0002 0.0002 Liver or kidney problems Runoff/leaching from insecticide used on catttle, lumber, gardens
Methoxychlor 0.04 0.04 Reproductive difficulties Runoff/leaching from insecticide used on fruits, vegetables, alfalfa, livestock
Oxamyl (Vydate) 0.2 0.2 Slight nervous system effects Runoff/leaching from insecticide used on apples, potatoes, and tomatoes
Polychlorinated biphenyls (PCBs) zero 0.0005 Skin changes; thymus gland problems; immune difficiencies; reproductive or nervous system difficulties; increased risk of cancer Runoff from landfils; discharge of waste chemicals
Pentachlorophenol zero 0.001 Liver or kidney problems; increased risk of cancer Discharge from wood preserving factories
Picloram 0.5 0.5 Liver problems Herbicide runoff
Simazine 0.004 0.004 Problems with blood Herbicide runoff
Styrene 0.1 0.1 Liver, kidney, and circulatory problems Discharge from rubber and plastic factories; leaching from landfills
Tetrachloroethylene zero 0.005 Liver problems; increased risk of cancer Leaching from PVC pipes; discharge from factories and dry cleaners
Toluene 1 1 Nervous system, kidney, or liver problems Discharge from petroleum factories
Total Trihalomethanes (TTHMs) none5 0.10 Liver, kidney or central nervous system problems; increased risk of cancer Byproduct of drinking water disinfection
Toxaphene zero 0.003 Kidney, liver, or thyroid problems; increased risk of cancer Runoff/leaching from insecticide used on cotton and cattle
2,4,5-TP (Silvex) 0.05 0.05 Liver problems Residue of banned herbicide
1,2,4-Trichlorobenzene 0.07 0.07 Changes in adrenal glands Discharge from textile finishing factories
1,1,1-Trichloroethane 0.20 0.2 Liver, nervous system, or circulatory problems Discharge from metal degreasing sites and other factories
1,1,2-Trichloroethane 0.003 0.005 Liver, kidney, or immune system problems Discharge from industrial chemical factories
Trichloroethylene zero 0.005 Liver problems; increased risk of cancer Discharge from petroleum refineries
Vinyl chloride zero 0.002 Increased risk of cancer Leaching from PVC pipes; discharge from plastic factories
Xylenes (total) 10 10 Nervous system damage Discharge from petroleum factories; discharge from chemical factories
Radionuclides
Beta particles and photon emitters none5 4 millirems per year Increased risk of cancer Decay of natural and man-made deposits
Gross alpha particle activity none5 15 picocuries per Liter (pCi/L) Increased risk of cancer Erosion of natural deposits
Radium 226 and Radium 228 (combined) none5 5 pCi/L Increased risk of cancer Erosion of natural deposits
Microorganisms
Giardia lamblia zero TT8 Giardiasis, a gastroenteric disease Human and animal fecal waste
Heterotrophic plate count N/A TT8 HPC has no health effects, but can indicate how effective treatment is at controlling microorganisms. n/a
Legionella zero TT8 Legionnaire's Disease, commonly known as pneumonia Found naturally in water; multiplies in heating systems
Total Coliforms (including fecal coliform and E. Coli) zero 5.0%9 Used as an indicator that other potentially harmful bacteria may be present10 Human and animal fecal waste
Turbidity N/A TT8 Turbidity has no health effects but can interfere with disinfection and provide a medium for microbial growth. It may indicate the presence of microbes. Soil runoff
Viruses (enteric) zero TT8 Gastroenteric disease Human and animal fecal waste
Table 1

National Secondary Drinking Water Regulations

National Secondary Drinking Water Regulations (NSDWRs or secondary 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. See Table 2.

Contaminant Secondary Standard
Aluminum0.05 to 0.2 mg/L
Chloride250 mg/L
Color15 (color units)
Copper1.0 mg/L
Corrosivitynoncorrosive
Fluoride2.0 mg/L
Foaming Agents0.5 mg/L
Iron0.3 mg/L
Manganese0.05 mg/L
Odor3 threshold odor number
pH6.5-8.5
Silver0.10 mg/L
Sulfate250 mg/L
Total Dissolved Solids500 mg/L
Zinc5 mg/L
Table 2

Notes

1 Maximum Contaminant Level Goal (MCLG) - The maximum level of a contaminant in drinking water at which no known or anticipated adverse effect on the health effect of persons would occur, and which allows for an adequate margin of safety. MCLGs are non-enforceable public health goals.

2 Maximum Contaminant Level (MCL) - The maximum permissible level of a contaminant in water which is delivered to any user of a public water system. MCLs are enforceable standards. The margins of safety in MCLGs ensure that exceeding the MCL slightly does not pose significant risk to public health.

3 Treatment Technique - An enforceable procedure or level of technical performance which public water systems must follow to ensure control of a contaminant.

4 Units are in milligrams per Liter (mg/L) unless otherwise noted.

5 MCLGs were not established before the 1986 Amendments to the Safe Drinking Water Act. Therefore, there is no MCLG for this contaminant.

6 Lead and copper are regulated in a Treatment Technique which requires systems to take tap water samples at sites with lead pipes or copper pipes that have lead solder and/or are served by lead service lines. The action level, which triggers water systems into taking treatment steps if exceeded in more than 10% of tap water samples, for copper is 1.3 mg/L, and for lead is 0.015mg/L.

7 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:

8 The Surface Water Treatment Rule requires systems using surface water or ground water under the direct influence of surface water to (1) disinfect their water, and (2) filter their water to meet criteria for avoiding filtration so that the following contaminants are controlled at the following levels:

9 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). Every sample that has total coliforms must be analyzed for fecal coliforms. There cannot be any fecal coliforms.

10 Fecal coliform and E. coli are bacteria whose presence indicates that the water may be contaminated witih human animal wastes. Microbes in these wastes can cause diarrhea, cramps, nausea, headaches, or other symptoms.

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