National Primary Drinking Water Standards


National Primary Drinking Water Standards
Contaminant
MCLG1
(mg/L)2
MCLor
TT1 (mg/L)2
Potential health effects from exposure
above the MCL
Common sources of contaminant in
drinking water
MICROORGANISMS " *%
Cryptosporidium
Giardia lamblia
Heterotrophic plate
count (HPC)
Legionella
Total Coliforms
(including fecal
coliform and E. coli)
Turbidity
Viruses (enteric)
zero
zero
n/a
zero
zero
n/a
zero
TT3
TT3
TT3
TT3
5.0%4
TT3
TT3
Gastrointestinal illness (e.g., diarrhea,
vomiting, cramps)
Gastrointestinal illness (e.g., diarrhea,
vomiting, cramps)
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.
Legionnaire's Disease, a type of pneumonia
Not a health threat in itself; it is used to
indicate whether other potentially harmful
bacteria may be present5
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 microorganisms such
as viruses, parasites and some bacteria. These
organisms can cause symptoms such as nausea,
cramps, diarrhea, and associated headaches.
Gastrointestinal illness (e.g., diarrhea,
vomiting, cramps)
Human and fecal animal waste
Human and animal fecal waste
HPC measures a range of bacteria
that are naturally present in the
environment
Found naturally in water; multiplies
in heating systems
Coliforms are naturally present in the
environment; as well as feces; fecal
coliforms and E. coli only come from
human and animal fecal waste.
Soil runoff
Human and animal fecal waste
DISINFECTION BYPRODUCTS
Bromate
Chlorite
Haloaeetic acids
(HAAS)
Total Trihalomethanes
(TTHMs)
DISINFECTANTS
Chloramines (as C12)
Chlorine (as C12)
zero
0.8
n/a6
none7
n/a6
MRDL ]
(mg/L)4
MRDJLG=4
MRDJLG=4
0.010
1.0
0.060
0.10
0.080
MKDL '
(mg/L)2
MRDL=4.0'
MRDL=4.0'
Increased risk of cancer
Anemia; infants & young children: nervous
system effects
Increased risk of cancer
Liver, kidney or central nervous system
problems; increased risk of cancer
Byproduct of drinking water
disinfection
Byproduct of drinking water
disinfection
Byproduct of drinking water
disinfection
Byproduct of drinking water
disinfection

Eye/nose irritation; stomach discomfort,
anemia
Eye/nose irritation; stomach discomfort
Water additive used to control
microbes
Water additive used to control
microbes

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Contaminant
Chlorine dioxide (as
C102)
MCLG1
(mg/L)2
MRDLG=0
.8'
MCLor
XT1 (mg/L)2
MRDL=0.8'
Potential health effects from exposure
above the MCL
Anemia; infants & young children: nervous
system effects
Common sources of contaminant in
drinking water
Water additive used to control
microbes
INORGANIC CHEMICALS " ' ' ." !-
Antimony
Arsenic
Asbestos
(fibers >10
micrometers)
Barium
Beryllium
Cadmium
Chromium (total)
Copper
Cyanide
(as free cyanide)
Fluoride
Lead
Mercury (inorganic)
Nitrate
(measured as
Nitrogen)
0.006
O7
7 million
fibers per
Liter
(MFL)
2
0.004
0.005
0.1
1.3
0.2
4.0
zero
0.002
10
0.006
0.010
as of
1/23/06
7 MFL
2
0.004
0.005
0.1
TT8;
Action
Level= 1.3
0.2
. 4.0
TT8;
Action
Level=
0.015
0.002
10
ncrease in blood cholesterol; decrease in blood
ugar
Skin damage or problems with circulatory
ystems, and may have increased risk of getting
cancer
ncreased risk of developing benign intestinal
>olyps
ncrease in blood pressure
intestinal lesions
Kidney damage
Allergic dermatitis
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
Nerve damage or thyroid problems
Bone disease (pain and tenderness of the
bones); Children may get mottled teeth
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
Kidney damage
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.
Discharge from petroleum refineries;
ire retardants; ceramics; electronics;
solder
Erosion of natural deposits; runoff
from orchards, runoff from glass &
electronicsproduction wastes
:, p ! i
Decay of asbestos cement in water
mains; erosion of natural deposits
Discharge of drilling wastes;
discharge from metal refineries;
erosion of natural deposits
Discharge from metal refineries and
coal-burning factories; discharge
from electrical, aerospace, and
defense industries
Corrosion of galvanized pipes;
erosion of natural deposits; discharge
from metal refineries; runoff from
waste batteries and paints
Discharge from steel and pulp mills;
erosion of natural deposits
Corrosion of household plumbing
systems; erosion of natural deposits
Discharge from steel/metal factories;
discharge from plastic and fertilizer
factories
Water additive which promotes
strong teeth; erosion of natural
deposits; discharge from fertilizer
and aluminum factories
	 - — - — 	 — .. '.. i
Corrosion of household plumbing
systems; erosion of natural deposits
Erosion of natural deposits;
discharge from refineries and
factories; runoff from landfills and
croplands
Runoff from fertilizer use; leaching
from septic tanks, sewage; erosion of
natural deposits

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	 r
Contaminant
Nitrite
(measured as
Nitrogen)
Selenium
Thallium
MCLG1
(mg/L)2
1
0.05
0.0005
MCLor
TT1 (mg/L)2
1
0.05
.6.002
Potential health effects from exposure
above the MCL
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.
Hair or fingernail loss; numbness in fingers or
toes; circulatory problems
Hair loss; changes in blood; kidney, intestine,
or liver problems
Common sources of contaminant in
drinking water
Runoff from fertilizer use; leaching
from septic tanks, sewage; erosion of
natural deposits
Discharge from petroleum refineries;
erosion of natural deposits; discharge
from mines
Leaching from ore-processing sites;
discharge from electronics, glass, and
drug factories
ORGANIC CHEMICALS
Acrylamide
Alachlor
Atrazine
Benzene
Benzo(a)pyrene
(PAHs)
Carbofuran
Carbon tetrachloride
Chlordane
Chlorobenzene
2,4-D
Dalapon
l,2-Dibromo-3-
chloropropane
(DBCP)
o-Dichlorobenzene
p-Dichlorobenzene
1 ,2-Dichloroethane
1 , 1 -Dichloroethylene
cis- 1 ,2-Dichloroethyle
ne
trans- 1,2-
Dichloroethylene
zero
zero
0.003
zero
zero
0.04
zero
zero
0.1
0.07
0.2
zero
0.6
0.075
zero
0.007
0.07
0.1
YF>
0.002
0.003
0.005
0.0002
0.04
0.005
0.002
0.1
0.07
0.2
0.0002
0.6
0.075
0.005
0.007
0.07
0.1
Nervous system or blood problems; increased
risk of cancer
Eye, liver, kidney or spleen problems; anemia;
increased risk of cancer
Cardiovascular system or reproductive
problems
Anemia; decrease in blood platelets; increased
risk of cancer
Reproductive difficulties; increased risk of
cancer
Problems with blood, nervous system, or
reproductive system
Liver problems; increased risk of cancer
Liver or nervous system problems; increased
risk of cancer
Liver or kidney problems
Kidney, liver, or adrenal gland problems
Minor kidney changes
Reproductive difficulties; increased risk of
cancer
Liver, kidney, or circulatory system problems
Anemia; liver, kidney or spleen damage;
changes in blood
Increased risk of cancer
Liver problems
Liver problems
Liver problems
Added to water during
sewage/wastewater treatment
Runoff from herbicide used on row
crops
Runoff from herbicide used on row
crops
Discharge from factories; leaching
from gas storage tanks and landfills
Leaching from linings of water
storage tanks and distribution lines
Leaching of soil fumigant used on
rice and alfalfa
Discharge from chemical plants and
other industrial activities
Residue of banned termiticide
Discharge from chemical and
agricultural chemical factories
Runoff from herbicide used on row •
crops
Runoff from herbicide used on rights
of way
Runoff/leaching from soil fumigant
used on soybeans, cotton,
pineapples, and orchards
Discharge from industrial chemical
factories
Discharge from industrial chemical
factories
Discharge from industrial chemical
factories
Discharge from industrial chemical
factories
Discharge from industrial chemical
factories
Discharge from industrial chemical
factories

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Contaminant
Dichloromethane
1 ,2-Dichloropropane
Di(2-ethylhexyl)
adipate
Di(2-ethylhexyl)
phthalate
Dinoseb
Dioxin
(2,3,7,8-TCDD)
Diquat
Endothall
Endrin
Epichlorohydrin
Ethylbenzene
Ethylene dibromide
Glyphosate
Hcptachlor
Hcptachlor epoxide
Hexachlorobenzene
Hexachlorocyclopent
adienc
Lindane
Methoxychlor
Oxamyl (Vydate)
Polychlorinated
biphenyls (PCBs)
Pentachlorophenol
Picloram
Simazine
Styrene
MCLG1
(mg/L)2
zero
zero
0.4
zero
0.007
zero
0.02
0.1
0.002
zero
0.7
zero
0.7
zero
zero
zero
0.05
0.0002
0.04 -,
0.2
zero
zero
0.5
0.004
0.1
MCLor
TT1 (mg/L)2
0.005
0.005
0.4
0.006
0.007
0.00000003
0.02
0.1
0.002
TT9
0.7
0.00005
0.7
0.0004
0.0002
0.001
0.05
0.0002
0.04
0.2
0.0005
0.001
0.5
0.004
0.1
Potential health effects from exposure
above the MCL
^iver problems; increased risk of cancer
1 •'. ' !' .!'„ "
ncreased risk of cancer
General toxic effects or reproductive
difficulties
Reproductive difficulties; liver problems;
ncreased risk of cancer
Reproductive difficulties
Reproductive difficulties; increased risk of
cancer
Cataracts
Stomach and intestinal problems
Liver problems
Increased cancer risk, and over a long period of
time, stomach problems
Liver or kidneys problems
Problems with liver, stomach, reproductive
system, or kidneys; increased risk of cancer
Kidney problems; reproductive difficulties
Liver damage; increased risk of cancer
Liver damage; increased risk of cancer
Liver or kidney problems; reproductive
difficulties; increased risk of cancer
Kidney or stomach problems
Liver or kidney problems
Reproductive difficulties
Slight nervous system effects
Skin changes; thyinus gland problems; immune
deficiencies; reproductive or nervous system
difficulties; increased risk of cancer
Liver or kidney problems; increased cancer risk
Liver problems
Problems with blood
Liver, kidney, or circulatory system problems
Common sources of contaminant in
drinking water
Discharge from drug and chemical
actories
Discharge from industrial chemical
actories
Discharge from chemical factories
Discharge from rubber and chemical
actories
Runoff from herbicide used on
soybeans and vegetables
Emissions from waste incineration
and other combustion; discharge
Tom chemical factories
Runoff from herbicide use
Runoff from herbicide use
Residue of banned insecticide
Discharge from industrial chemical
factories; an impurity of some water
treatment chemicals
Discharge from petroleum refineries
Discharge from petroleum refineries
Runoff from herbicide use
Residue of banned termiticide
Breakdown of heptachlor
Discharge from metal refineries and
agricultural chemical factories
Discharge from chemical factories
i , ,|
Runoff/leaching from insecticide
used on cattle, lumber, gardens
Runoff/leaching from insecticide
used on fruits, vegetables, alfalfa,
livestock
Runoff/leaching from insecticide
used on apples, potatoes, and
tomatoes
Runoff from landfills; discharge of
waste chemicals
Discharge from wood preserving
factories
Herbicide runoff
Herbicide runoff
Discharge from rubber and plastic
factories; leaching from landfills

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Contaminant
Tetrachloroethylene
Toluene
Toxaphene
2,4,5-TP (Silvex)
1 ,2,4-Trichlorobenzen
e
1,1,1 -Trichloroethane
1 , 1 ,2-Trichloroethane
Trichloroethylene
Vinyl chloride
Xylenes (total)
MCLG1
(mg/L)2
zero
1
zero
0.05
0.07
0.20
0.003
zero
zero
10
MCL or
TT1 (mg/L)2
0.005
1
0.003
0.05
0.07
0.2
0.005
0.005
0.002
10
Potential health effects from exposure
abov4 the MCL
Liver problems; increased risk of cancer
Nervous system, kidney, or liver problems
Kidney, liver, or thyroid problems; increased
risk of cancer
Liver problems
Changes in adrenal glands
Liver, nervous system, or circulatory problems
Liver, kidney, or immune system problems
Liver problems; increased risk of cancer
Increased risk of cancer
Nervous system damage
Common sources of contaminant in
drinking water
Discharge from factories and dry
cleaners
Discharge from petroleum factories
Runoff/leaching from insecticide
used on cotton and cattle
Residue of banned herbicide
Discharge from textile finishing
factories
Discharge from metal degreasing
sites and other factories
Discharge from industrial chemical
factories
Discharge from metal degreasing
sites and other factories
Leaching from PVC pipes; discharge
from plastic factories
Discharge from petroleum factories;
discharge from chemical factories
KJtolOWCUDES
Alpha particles
Beta particles and
photon emitters
Radium 226 and
Radium 228
(combined)
Uranium
none7
none7
none7
zero
15
picocuries
per Liter
(pCi/L)
4 millirems
per year
(mrem/yr)
5pCi/L
30 ug/L
as of
., 12/08/03
Increased risk of cancer
Increased risk of cancer
Increased risk of cancer
Increased risk of cancer, kidney toxicity
Erosion of natural deposits of certain
minerals that are radioactive and may
emit a form of radiation known as
alpha radiation
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
Erosion of natural deposits
Erosion of natural deposits
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.

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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 ofl/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, 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£. coll 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 - MCLGs were not established before the 1986 Amendments to the Safe Drinking Water Act. The standard for this contaminant was set
prior to 1986. 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 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).
For More Information:
Call the Safe Drinking Water Hotline, 1-800-426-4791
Office of Water (4606)
EPA 816-F-02-013
www.epa.gov/safewater
July 2002

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