The National Primary Drinking Water Regulations (NPDWR) are legally enforceable primary standards and treatment techniques that apply to public water systems. Primary standards and treatment techniques protect public health by limiting the levels of contaminants in drinking water.

Printable version: Complete NPDWR Table

Microorganisms Surface Water Treatment Rules Summary Contaminant MCLG1 (mg/L)2 MCL or TT1 (mg/L)2 Potential Health Effects from Long-Term Exposure Above the MCL (unless specified as short-term) Sources of Contaminant in Drinking Water Cryptosporidium zero TT3 Gastrointestinal illness (such as diarrhea, vomiting, and cramps) Human and animal fecal waste Giardia lamblia zero TT3 Gastrointestinal illness (such as diarrhea, vomiting, and cramps) Human and animal fecal waste Heterotrophic plate count (HPC) n/a 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 Legionella zero TT3 Legionnaire's Disease, a type of pneumonia Found naturally in water; multiplies in heating systems Total Coliforms (including fecal coliform and E. Coli) Quick reference guide

Rule Summary zero 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. Turbidity n/a TT3 Turbidity is a measure of the cloudiness of water. It is used to indicate water quality and filtration effectiveness (such as whether disease-causing organisms are present). Higher turbidity levels are often associated with higher levels of disease-causing microorganisms such as viruses, parasites and some bacteria. These organisms can cause symptoms such as nausea, cramps, diarrhea, and associated headaches. Soil runoff Viruses (enteric) zero TT3 Gastrointestinal illness (such as diarrhea, vomiting, and cramps) Human and animal fecal waste

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Inorganic Chemicals Chemical Contaminant Rules Summary Contaminant MCLG1 (mg/L)2 MCL or TT1 (mg/L)2 Potential Health Effects from Long-Term Exposure Above the MCL (unless specified as short-term) Sources of Contaminant in Drinking Water Antimony 0.006 0.006 Increase in blood cholesterol; decrease in blood sugar Discharge from petroleum refineries; fire retardants; ceramics; electronics; solder Arsenic Quick reference guide

Consumer fact sheet 0 0.010 as of 01/23/06 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 and electronicsproduction wastes Asbestos (fiber > 10 micrometers) 7 million fibers per liter (MFL) 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 Allergic dermatitis Discharge from steel and pulp mills; erosion of natural deposits Copper 1.3 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 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 Quick reference guide

Rule information zero 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 Mercury (inorganic) 0.002 0.002 Kidney damage Erosion of natural deposits; discharge from refineries and factories; runoff from landfills and croplands Nitrate (measured as Nitrogen) 10 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; leaking from septic tanks, sewage; erosion of natural deposits Nitrite (measured as Nitrogen) 1 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; leaking 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 drug factories

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Organic Chemicals Chemical Contaminant Rules Summary Contaminant MCLG1 (mg/L)2 MCL or TT1 (mg/L)2 Potential Health Effects from Long-Term Exposure Above the MCL (unless specified as short-term) Sources of Contaminant in Drinking Water Acrylamide zero TT8 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 or reproductive problems 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 (PAHs) 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, nervous system, or reproductive system Leaching of soil fumigant used on rice and alfalfa Carbon tetrachloride zero 0.005 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 Discharge 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 drug 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 Weight loss, liver problems, or possible reproductive difficulties. 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 Liver problems Residue of banned insecticide Epichlorohydrin zero 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 Ethylbenzene 0.7 0.7 Liver or kidneys problems Discharge from petroleum refineries Ethylene dibromide zero 0.00005 Problems with liver, stomach, reproductive system, or kidneys; 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 heptachlor 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 cattle, 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 deficiencies; reproductive or nervous system difficulties; increased risk of cancer Runoff from landfills; discharge of waste chemicals Pentachlorophenol zero 0.001 Liver or kidney problems; increased cancer risk 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, or circulatory system problems Discharge from rubber and plastic factories; leaching from landfills Tetrachloroethylene zero 0.005 Liver problems; increased risk of cancer Discharge from factories and dry cleaners Toluene 1 1 Nervous system, kidney, or liver problems Discharge from petroleum factories 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 metal degreasing sites and other factories 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

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Radionuclides Quick Reference Guide Radionuclides Rule Information and Summary Contaminant MCLG1 (mg/L)2 MCL or TT1 (mg/L)2 Potential Health Effects from Long-Term Exposure Above the MCL (unless specified as short-term) Sources of Contaminant in Drinking Water Alpha particles none ---------- zero 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 Beta particles and photon emitters none ---------- zero 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 Radium 226 and Radium 228 (combined) none ---------- zero 5 pCi/L Increased risk of cancer Erosion of natural deposits Uranium zero 30 ug/L as of 12/08/03 Increased risk of cancer, kidney toxicity Erosion of natural deposits

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Notes

1Definitions:

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.

Treatment Technique (TT) - 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 (PPM).



3 EPA's surface water treatment rules require systems using surface water or ground water under the direct influence of surface water to

Disinfect their water, and Filter their water, or Meet criteria for avoiding filtration so that the following contaminants are controlled at the following levels:

Cryptosporidium: Unfiltered systems are required to include Cryptosporidium in their existing watershed control provisions

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, according to the treatment techniques in the Surface Water Treatment Rule, Legionella will also be controlled.

Turbidity: For systems that use conventional or direct filtration, at no time can turbidity (cloudiness of water) go higher than 1 Nephelometric Turbidity Unit (NTU), and samples for turbidity must be less than or equal to 0.3 NTUs in at least 95 percent of the samples in any month. Systems that use filtration other than the conventional or direct filtration must follow state limits, which must include turbidity at no time exceeding 5 NTUs.

Heterotrophic Plate Count (HPC): No more than 500 bacterial colonies per milliliter.

Long Term 1 Enhanced Surface Water Treatment: Surface water systems or groundwater under the direct influence (GWUDI) systems serving fewer than 10,000 people must comply with the applicable Long Term 1 Enhanced Surface Water Treatment Rule provisions (such as turbidity standards, individual filter monitoring, Cryptosporidium removal requirements, updated watershed control requirements for unfiltered systems).

Long Term 2 Enhanced Surface Water Treatment Rule: This rule applies to all surface water systems or ground water systems under the direct influence of surface water. The rule targets additional Cryptosporidium treatment requirements for higher risk systems and includes provisions to reduce risks from uncovered finished water storage facilities and to ensure that the systems maintain microbial protection as they take steps to reduce the formation of disinfection byproducts.

Filter Backwash Recycling: This 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 (TC-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:

Trihalomethanes: bromodichloromethane (zero); bromoform (zero); dibromochloromethane (0.06 mg/L): chloroform (0.07 mg/L.

Haloacetic acids: dichloroacetic acid (zero); trichloroacetic acid (0.02 mg/L); monochloroacetic acid (0.07mg/L). Bromoacetic acid and dibromoacetic acid are regulated with this group but have no MCLGs.

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 manufacturer's certification) that when acrylamide and epichlorohydrin are used 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)

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