• August

    14

    2018
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National Primary Drinking Water Regulations

National Primary Drinking Water Regulations

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
ContaminantMCLG1(mg/L)2MCL or TT1(mg/L)2Potential Health Effects from Long-Term Exposure Above the MCL (unless specified as short-term)Sources of Contaminant in Drinking Water
CryptosporidiumzeroTT3Gastrointestinal illness (such as diarrhea, vomiting, and cramps)Human and animal fecal waste
Giardia lambliazeroTT3Gastrointestinal illness (such as diarrhea, vomiting, and cramps)Human and animal fecal waste
Heterotrophic plate count (HPC)n/aTT3HPC 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
LegionellazeroTT3Legionnaire’s Disease, a type of pneumoniaFound naturally in water; multiplies in heating systems
Total Coliforms (including fecal coliform and E. Coli)

zero5.0%4Not a health threat in itself; it is used to indicate whether other potentially harmful bacteria may be present5Coliforms are naturally present in the environment; as well as feces; fecal coliforms and E. coli only come from human and animal fecal waste.
Turbidityn/aTT3Turbidity 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)zeroTT3Gastrointestinal illness (such as diarrhea, vomiting, and cramps)Human and animal fecal waste

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Disinfection Byproducts

Quick reference guide: Stage 1 and 2 Disinfectants and Disinfection Byproducts Rules

ContaminantMCLG1(mg/L)2MCL or TT1(mg/L)2Potential Health Effects from Long-Term Exposure Above the MCL (unless specified as short-term)Sources of Contaminant in Drinking Water
Bromatezero0.010Increased risk of cancerByproduct of drinking water disinfection
Chlorite0.81.0Anemia; infants and young children: nervous system effectsByproduct of drinking water disinfection
Haloacetic acids (HAA5)n/a60.060Increased risk of cancerByproduct of drinking water disinfection
Total Trihalomethanes (TTHMs)–> n/a6========–>–> 0.080Liver, kidney or central nervous system problems; increased risk of cancerByproduct of drinking water disinfection

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Disinfectants

Quick reference guide: Stage 1 and 2 Disinfectants and Disinfection Byproducts Rules

ContaminantMCLG1(mg/L)2MCL or TT1(mg/L)2Potential Health Effects from Long-Term Exposure Above the MCL (unless specified as short-term)Sources of Contaminant in Drinking Water
Chloramines (as Cl2)MRDLG=41MRDL=4.01Eye/nose irritation; stomach discomfort, anemiaWater additive used to control microbes
Chlorine (as Cl2)MRDLG=41MRDL=4.01Eye/nose irritation; stomach discomfortWater additive used to control microbes
Chlorine dioxide (as ClO2)MRDLG=0.81MRDL=0.81Anemia; infants and young children: nervous system effectsWater additive used to control microbes

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Inorganic Chemicals
ContaminantMCLG1(mg/L)2MCL or TT1(mg/L)2Potential Health Effects from Long-Term Exposure Above the MCL (unless specified as short-term)Sources of Contaminant in Drinking Water
Antimony0.0060.006Increase in blood cholesterol; decrease in blood sugarDischarge from petroleum refineries; fire retardants; ceramics; electronics; solder
Arsenic

00.010 as of 01/23/06Skin damage or problems with circulatory systems, and may have increased risk of getting cancerErosion of natural deposits; runoff from orchards, runoff from glass and electronicsproduction wastes
Asbestos (fiber > 10 micrometers)7 million fibers per liter (MFL)7 MFLIncreased risk of developing benign intestinal polypsDecay of asbestos cement in water mains; erosion of natural deposits
Barium22Increase in blood pressureDischarge of drilling wastes; discharge from metal refineries; erosion of natural deposits
Beryllium0.0040.004Intestinal lesionsDischarge from metal refineries and coal-burning factories; discharge from electrical, aerospace, and defense industries
Cadmium0.0050.005Kidney damageCorrosion of galvanized pipes; erosion of natural deposits; discharge from metal refineries; runoff from waste batteries and paints
Chromium (total)0.10.1Allergic dermatitisDischarge from steel and pulp mills; erosion of natural deposits
Copper1.3TT7; Action Level=1.3Short 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)0.20.2Nerve damage or thyroid problemsDischarge from steel/metal factories; discharge from plastic and fertilizer factories
Fluoride4.04.0Bone disease (pain and tenderness of the bones); Children may get mottled teethWater additive which promotes strong teeth; erosion of natural deposits; discharge from fertilizer and aluminum factories
Lead

zeroTT7; Action Level=0.015Infants 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)0.0020.002Kidney damageErosion of natural deposits; discharge from refineries and factories; runoff from landfills and croplands
Nitrate (measured as Nitrogen)1010Infants 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)11Infants 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
Selenium0.050.05Hair or fingernail loss; numbness in fingers or toes; circulatory problemsDischarge from petroleum refineries; erosion of natural deposits; discharge from mines
Thallium0.00050.002Hair loss; changes in blood; kidney, intestine, or liver problemsLeaching from ore-processing sites; discharge from electronics, glass, and drug factories

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Organic Chemicals
ContaminantMCLG1(mg/L)2MCL or TT1(mg/L)2Potential Health Effects from Long-Term Exposure Above the MCL (unless specified as short-term)Sources of Contaminant in Drinking Water
AcrylamidezeroTT8Nervous system or blood problems; increased risk of cancerAdded to water during sewage/wastewater treatment
Alachlorzero0.002Eye, liver, kidney or spleen problems; anemia; increased risk of cancerRunoff from herbicide used on row crops
Atrazine0.0030.003Cardiovascular system or reproductive problemsRunoff from herbicide used on row crops
Benzenezero0.005Anemia; decrease in blood platelets; increased risk of cancerDischarge from factories; leaching from gas storage tanks and landfills
Benzo(a)pyrene (PAHs)zero0.0002Reproductive difficulties; increased risk of cancerLeaching from linings of water storage tanks and distribution lines
Carbofuran0.040.04Problems with blood, nervous system, or reproductive systemLeaching of soil fumigant used on rice and alfalfa
Carbon tetrachloridezero0.005Liver problems; increased risk of cancerDischarge from chemical plants and other industrial activities
Chlordanezero0.002Liver or nervous system problems; increased risk of cancerResidue of banned termiticide
Chlorobenzene0.10.1Liver or kidney problemsDischarge from chemical and agricultural chemical factories
2,4-D0.070.07Kidney, liver, or adrenal gland problemsRunoff from herbicide used on row crops
Dalapon0.20.2Minor kidney changesRunoff from herbicide used on rights of way
1,2-Dibromo-3-chloropropane (DBCP)zero0.0002Reproductive difficulties; increased risk of cancerRunoff/leaching from soil fumigant used on soybeans, cotton, pineapples, and orchards
o-Dichlorobenzene0.60.6Liver, kidney, or circulatory system problemsDischarge from industrial chemical factories
p-Dichlorobenzene0.0750.075Anemia; liver, kidney or spleen damage; changes in bloodDischarge from industrial chemical factories
1,2-Dichloroethanezero0.005Increased risk of cancerDischarge from industrial chemical factories
1,1-Dichloroethylene0.0070.007Liver problemsDischarge from industrial chemical factories
cis-1,2-Dichloroethylene0.070.07Liver problemsDischarge from industrial chemical factories
trans-1,2-Dichloroethylene0.10.1Liver problemsDischarge from industrial chemical factories
Dichloromethanezero0.005Liver problems; increased risk of cancerDischarge from drug and chemical factories
1,2-Dichloropropanezero0.005Increased risk of cancerDischarge from industrial chemical factories
Di(2-ethylhexyl) adipate0.40.4Weight loss, liver problems, or possible reproductive difficulties.Discharge from chemical factories
Di(2-ethylhexyl) phthalatezero0.006Reproductive difficulties; liver problems; increased risk of cancerDischarge from rubber and chemical factories
Dinoseb0.0070.007Reproductive difficultiesRunoff from herbicide used on soybeans and vegetables
Dioxin (2,3,7,8-TCDD)zero0.00000003Reproductive difficulties; increased risk of cancerEmissions from waste incineration and other combustion; discharge from chemical factories
Diquat0.020.02CataractsRunoff from herbicide use
Endothall0.10.1Stomach and intestinal problemsRunoff from herbicide use
Endrin0.0020.002Liver problemsResidue of banned insecticide
EpichlorohydrinzeroTT8Increased cancer risk, and over a long period of time, stomach problemsDischarge from industrial chemical factories; an impurity of some water treatment chemicals
Ethylbenzene0.70.7Liver or kidneys problemsDischarge from petroleum refineries
Ethylene dibromidezero0.00005Problems with liver, stomach, reproductive system, or kidneys; increased risk of cancerDischarge from petroleum refineries
Glyphosate0.70.7Kidney problems; reproductive difficultiesRunoff from herbicide use
Heptachlorzero0.0004Liver damage; increased risk of cancerResidue of banned termiticide
Heptachlor epoxidezero0.0002Liver damage; increased risk of cancerBreakdown of heptachlor
Hexachlorobenzenezero0.001Liver or kidney problems; reproductive difficulties; increased risk of cancerDischarge from metal refineries and agricultural chemical factories
Hexachlorocyclopentadiene0.050.05Kidney or stomach problemsDischarge from chemical factories
Lindane0.00020.0002Liver or kidney problemsRunoff/leaching from insecticide used on cattle, lumber, gardens
Methoxychlor0.040.04Reproductive difficultiesRunoff/leaching from insecticide used on fruits, vegetables, alfalfa, livestock
Oxamyl (Vydate)0.20.2Slight nervous system effectsRunoff/leaching from insecticide used on apples, potatoes, and tomatoes
Polychlorinated biphenyls (PCBs)zero0.0005Skin changes; thymus gland problems; immune deficiencies; reproductive or nervous system difficulties; increased risk of cancerRunoff from landfills; discharge of waste chemicals
Pentachlorophenolzero0.001Liver or kidney problems; increased cancer riskDischarge from wood preserving factories
Picloram0.50.5Liver problemsHerbicide runoff
Simazine0.0040.004Problems with bloodHerbicide runoff
Styrene0.10.1Liver, kidney, or circulatory system problemsDischarge from rubber and plastic factories; leaching from landfills
Tetrachloroethylenezero0.005Liver problems; increased risk of cancerDischarge from factories and dry cleaners
Toluene11Nervous system, kidney, or liver problemsDischarge from petroleum factories
Toxaphenezero0.003Kidney, liver, or thyroid problems; increased risk of cancerRunoff/leaching from insecticide used on cotton and cattle
2,4,5-TP (Silvex)0.050.05Liver problemsResidue of banned herbicide
1,2,4-Trichlorobenzene0.070.07Changes in adrenal glandsDischarge from textile finishing factories
1,1,1-Trichloroethane0.200.2Liver, nervous system, or circulatory problemsDischarge from metal degreasing sites and other factories
1,1,2-Trichloroethane0.0030.005Liver, kidney, or immune system problemsDischarge from industrial chemical factories
Trichloroethylenezero0.005Liver problems; increased risk of cancerDischarge from metal degreasing sites and other factories
Vinyl chloridezero0.002Increased risk of cancerLeaching from PVC pipes; discharge from plastic factories
Xylenes (total)1010Nervous system damageDischarge from petroleum factories; discharge from chemical factories

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Radionuclides

Quick Reference Guide

ContaminantMCLG1(mg/L)2MCL or TT1(mg/L)2Potential Health Effects from Long-Term Exposure Above the MCL (unless specified as short-term)Sources of Contaminant in Drinking Water
Alpha particlesnone ———- zero15 picocuries per Liter (pCi/L)Increased risk of cancerErosion of natural deposits of certain minerals that are radioactive and may emit a form of radiation known as alpha radiation
Beta particles and photon emittersnone ———- zero4 millirems per yearIncreased risk of cancerDecay 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 ———- zero5 pCi/LIncreased risk of cancerErosion of natural deposits
Uraniumzero30 ug/L as of 12/08/03Increased risk of cancer, kidney toxicityErosion 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.

Units are in milligrams per liter (mg/L) unless otherwise noted. Milligrams per liter are equivalent to parts per million (PPM).
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
  3. 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 additionalCryptosporidium 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 violaton.

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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