oEPA National Primary Drinking Water Standards

Contaminant
MCLorTTl
(mg/L)2
Potential health effects from
exposure above the MCL
Common sources of
contaminant in drinking water
Public
Health Goal
oc
Acrylamide
TT8
Nervous system or blood problems;
Added to water during
sewage/wastewater increased
risk of cancer treatment
zero
oc
Alachlor
0.002
Eye, liver, kidney or spleen problems;
anemia; increased risk of cancer
Runoff from herbicide used on
row crops
zero
R
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
IOC
Antimony
0.006
Increase in blood cholesterol; decrease in
blood sugar
Discharge from petroleum
refineries; fire retardants;
ceramics; electronics; solder
0.006
IOC
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
IOC
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
oc
Atrazine
0.003
Cardiovascular system or reproductive
problems
Runoff from herbicide used on
row crops
0.003
IOC
Barium
2
Increase in blood pressure
Discharge of drilling wastes;
discharge from metal refineries;
erosion of natural deposits
2
oc
Benzene
0.005
Anemia; decrease in blood platelets;
increased risk of cancer
Discharge from factories;
leaching from gas storage tanks
and landfills
zero
oc
Benzo(a)pyrene (PAHs)
0.0002
Reproductive difficulties; increased risk of
cancer
Leaching from linings of water
storage tanks and distribution
lines
zero
IOC
Beryllium
0.004
Intestinal lesions
Discharge from metal refineries
and coal-burning factories;
discharge from electrical,
aerospace, and defense
industries
0.004
R
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
DBP
Bromate
0.010
Increased risk of cancer
Byproduct of drinking water
disinfection
zero
IOC
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
OC
Carbofuran
0.04
Problems with blood, nervous system, or
reproductive system
Leaching of soil fumigant used on
rice and alfalfa
0.04
OC
Carbon tetrachloride
0.005
Liver problems; increased risk of cancer
Discharge from chemical plants
and other industrial activities
zero
D
Chloramines (as CI2)
MRDL=4.01
Eye/nose irritation; stomach discomfort,
anemia
Water additive used to control
microbes
MRDLG=41
LEGEND
Dinsinfectant
Disinfection Byproduct
Inorganic Chemical
Microorganism
Organic Chemical
Radionuclides

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Contaminant
MCLorTTl
(mg/L)2
Potential health effects from
exposure above the MCL
Common sources of
contaminant in drinking water
Public
Health Goal
oc
Chlordane
0.002
Liver or nervous system problems; increased
risk of cancer
Residue of banned termiticide
zero
D
Chlorine (as CI2)
MRDL=4.01
Eye/nose irritation; stomach discomfort
Water additive used to control
microbes
MRDLG=41
D
Chlorine dioxide (as CIO2)
MRDL=0.81
Anemia; infants & young children: nervous
system effects
Water additive used to control
microbes
MRDLG=0.81
DBP
Chlorite
1.0
Anemia; infants & young children: nervous
system effects
Byproduct of drinking water
disinfection
0.8
OC
Chlorobenzene
0.1
Liver or kidney problems
Discharge from chemical and
agricultural chemical factories
0.1
IOC
Chromium (total)
0.1
Allergic dermatitis
Discharge from steel and pulp
mills; erosion of natural deposits
0.1
IOC
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
M
Cryptosporidium
TT3
Gastrointestinal illness (e.g., diarrhea,
vomiting, cramps)
Human and animal fecal waste
zero
IOC
Cyanide (as free cyanide)
0.2
Nerve damage or thyroid problems
Discharge from steel/metal
factories; discharge from plastic
and fertilizer factories
0.2
OC
2,4-D
0.07
Kidney, liver, or adrenal gland problems
Runoff from herbicide used on
row crops
0.07
OC
Dalapon
0.2
Minor kidney changes
Runoff from herbicide used on
rights of way
0.2
OC
1,2-Dibromo-3-chloropropa
ne (DBCP)
0.0002
Reproductive difficulties; increased risk of
cancer
Runoff/leaching from soil
fumigant used on soybeans,
cotton, pineapples, and orchards
zero
OC
o-Dichlorobenzene
0.6
Liver, kidney, or circulatory system problems
Discharge from industrial
chemical factories
0.6
OC
p-Dichlorobenzene
0.075
Anemia; liver, kidney or spleen damage;
changes in blood
Discharge from industrial
chemical factories
0.075
OC
1,2-Dichloroethane
0.005
Increased risk of cancer
Discharge from industrial
chemical factories
zero
OC
1,1-Dichloroethylene
0.007
Liver problems
Discharge from industrial
chemical factories
0.007
OC
cis-1,2-Dichloroethylene
0.07
Liver problems
Discharge from industrial
chemical factories
0.07
OC
trans-1,2-Dichloroethylene
0.1
Liver problems
Discharge from industrial
chemical factories
0.1
OC
Dichloromethane
0.005
Liver problems; increased risk of cancer
Discharge from drug and
chemical factories
zero
OC
1,2-Dichloropropane
0.005
Increased risk of cancer
Discharge from industrial
chemical factories
zero
OC
Di(2-ethylhexyl) adipate
0.4
Weight loss, live problems, or possible
reproductive difficulties
Discharge from chemical
factories
0.4
OC
Di(2-ethylhexyl) phthalate
0.006
Reproductive difficulties; liver problems;
increased risk of cancer
Discharge from rubber and
chemical factories
zero
OC
Dinoseb
0.007
Reproductive difficulties
Runoff from herbicide used on
soybeans and vegetables
0.007
OC
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
OC
Diquat
0.02
Cataracts
Runoff from herbicide use
0.02
OC
Endothall
0.1
Stomach and intestinal problems
Runoff from herbicide use
0.1
LEGEND
D
DBP
Dinsinfectant
Disinfection Byproduct
Inorganic Chemical
Microorganism
Organic Chemical
Radionuclides

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Contaminant
MCLorTTl
Potential health effects from
Common sources of
Public

(mg/L)2
exposure above the MCL
contaminant in drinking water
Health Goal
oc
Endrin
0.002
Liver problems
Residue of banned insecticide
0.002
oc
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
oc
Ethylbenzene
0.7
Liver or kidneys problems
Discharge from petroleum
refineries
0.7
oc
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
Water additive which promotes
4.0
IOC


bones); Children may get mottled teeth
strong teeth; erosion of natural
deposits; discharge from fertilizer
and aluminum factories

M
Giardia lamblia
TT3
Gastrointestinal illness (e.g., diarrhea,
Human and animal fecal waste
zero


vomiting, cramps)


oc
Glyphosate
0.7
Kidney problems; reproductive difficulties
Runoff from herbicide use
0.7
DBP
Haloacetic acids (HAA5)
0.060
Increased risk of cancer
Byproduct of drinking water
disinfection
n/a6
OC
Heptachlor
0.0004
Liver damage; increased risk of cancer
Residue of banned termiticide
zero
OC
Heptachior 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
HPC measures a range of
bacteria that are naturally present
in the environment
n/a







the concentration of bacteria in drinking





water, the better maintained the water





system is.


oc
Hexachlorobenzene
0.001
Liver or kidney problems; reproductive
difficulties; increased risk of cancer
Discharge from metal refineries
and agricultural chemical
factories
zero
oc
Hexachlorocyclopentadien
e
0.05
Kidney or stomach problems
Discharge from chemical
factories
0.05
IOC
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
M
Legionella
TT3
Legionnaire's Disease, a type of pneumonia
Found naturally in water;
multiplies in heating systems
zero
OC
Lindane
0.0002
Liver or kidney problems
Runoff/leaching from insecticide
used on cattle, lumber, gardens
0.0002
IOC
Mercury (inorganic)
0.002
Kidney damage
Erosion of natural deposits;
discharge from refineries and
factories; runoff from landfills and
croplands
0.002
oc
Methoxychlor
0.04
Reproductive difficulties
Runoff/leaching from insecticide
used on fruits, vegetables, alfalfa,
livestock
0.04
IOC
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
IOC
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
LEGEND
Dinsinfectant
Disinfection Byproduct
Inorganic Chemical
Microorganism
Organic Chemical
Radionuclides

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Contaminant
MCLorTTl
(mg/L)2
Potential health effects from
exposure above the MCL
Common sources of
contaminant in drinking water
Public
Health Goal
oc
Oxamyl (Vydate)
0.2
Slight nervous system effects
Runoff/leaching from insecticide
used on apples, potatoes, and
tomatoes
0.2
oc
Pentachlorophenol
0.001
Liver or kidney problems; increased cancer
risk
Discharge from wood preserving
factories
zero
oc
Picloram
0.5
Liver problems
Herbicide runoff
0.5
oc
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
R
Radium 226 and Radium
228 (combined)
5 pCi/L
Increased risk of cancer
Erosion of natural deposits
zero
IOC
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
oc
Simazine
0.004
Problems with blood
Herbicide runoff
0.004
oc
Styrene
0.1
Liver, kidney, or circulatory system problems
Discharge from rubber and plastic
factories; leaching from landfills
0.1
oc
Tetrachloroethylene
0.005
Liver problems; increased risk of cancer
Discharge from factories and dry
cleaners
zero
IOC
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
oc
Toluene
1
Nervous system, kidney, or liver problems
Discharge from petroleum
factories
1
M
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
DBP
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





OC
Toxaphene
0.003
Kidney, liver, or thyroid problems; increased
risk of cancer
Runoff/leaching from insecticide
used on cotton and cattle
zero
OC
2,4,5-TP (Silvex)
0.05
Liver problems
Residue of banned herbicide
0.05
OC
1,2,4-Trichlorobenzene
0.07
Changes in adrenal glands
Discharge from textile finishing
factories
0.07
OC
1,1,1-Trichloroethane
0.2
Liver, nervous system, or circulatory
problems
Discharge from metal degreasing
sites and other factories
0.20
OC
1,1,2-Trichloroethane
0.005
Liver, kidney, or immune system problems
Discharge from industrial
chemical factories
0.003
oc
Trichloroethylene
0.005
Liver problems; increased risk of cancer
Discharge from metal degreasing
sites and other factories
zero
M
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
p
Uranium
30 ug/L
as of
12/08/03
Increased risk of cancer, kidney toxicity
Erosion of natural deposits
zero





LEGEND
Dinsinfectant
Disinfection Byproduct
Inorganic Chemical
Microorganism
Organic Chemical
Radionuclides

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Contaminant
MCLorTTl
Potential health effects from
Common sources of
Public

(mg/L)2
exposure above the MCL
contaminant in drinking water
Health Goal
oc
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% rem ova l/in activation
•	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 nephelometric 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 orE. coli if two consecutive TC-positive samples, and one is also positive forE. 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).
LEGEND
D
DBP
Dinsinfectant
Disinfection Byproduct
Inorganic Chemical
Microorganism
Organic Chemical
Radionuclides

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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.
Contaminant
Secondary Standard
Aluminum
0.05to0.2mg/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
Office of Water (4606M)
EPA 816-F-03-016
www.epa.gov/safewater
June 2003
6

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