National Primary Drinking Water Regulations
CLor
(mg/L)2
Potential health effects from
long-term3 exposure above the MCL
Common sources of contaminant
in drinking water
Nervous system or blood problems;
increased risk of cancer
Added to water during sewage/
wastewater treatment
Eye, liver, kidney or spleen problems;
anemia; increased risk of cancer
Runoff from herbicide
used on row crops
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
Increase in blood cholesterol; decrease
in blood sugar
Discharge from petroleum refineries;
fire retardants; ceramics; electronics;
solder
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
Increase in blood pressure
Discharge of drilling wastes; discharge
from metal refineries; erosion
of natural deposits
Anemia; decrease in blood platelets;
increased risk of cancer
Discharge from factories; leaching
from gas storage tanks and landfills
Reproductive difficulties; increased risk
of cancer
Leaching from linings of water storage
tanks and distribution lines
Intestinal lesions
Discharge from metal refineries and
coal-burning factories; discharge
from electrical, aerospace, and
defense industries
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
Public Health
Goal (mg/L)2
0.006
7 million
fibers per
,iter (MFL)
0.003
Increased risk of developing benign
intestinal polyps
Cardiovascular system or reproductive
problems
Decay of asbestos cement in water
mains; erosion of natural deposits
Runoff from herbicide used on row
crops
7 MFL
0.003
0.004
Increased risk of cancer
Byproduct of drinking water disinfection
Kidney damage
Corrosion of galvanized pipes; erosion
of natural deposits; discharge
from metal refineries; runoff from
waste batteries and paints
Problems with blood, nervous system, or
reproductive system
Leaching of soil fumigant used on rice
and alfalfa
Liver problems; increased risk of cancer
Discharge from chemical plants and
other industrial activities
Eye/nose irritation; stomach discomfort;
anemia
Water additive used to control
microbes
Liver or nervous system problems;
increased risk of cancer
Residue of banned termiticide
Eye/nose irritation; stomach discomfort
Water additive used to control
microbes
0.04
MRDLG=41
MRDLG=41
Anemia; infants, young children, and fetuses of
pregnant women: nervous system effects
Water additive used to control
microbes
Anemia; infants, young children, and fetuses of
pregnant women: nervous system effects
Byproduct of drinking water
disinfection
Liver or kidney problems
Discharge from chemical and agricultural
chemical factories
Allergic dermatitis
Discharge from steel and pulp mills;
erosion of natural deposits
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
Short-term exposure: Gastrointestinal illness
(e.g., diarrhea, vomiting, cramps)
Human and animal fecal waste
MRDLGO.8
1.3
Disinfectant
Disinfection Byproduct
Inorganic Chemical
Microorganism
| Organic Chemical
| Radionuclides
-------
Contaminant
MCLor
TT1 (mg/L)2
Potential health effects from
long-term3 exposure above the MCL
Common sources of contaminant
in drinking water
Liver problems
Liver problems
Liver problems
1,1 -Dichloroethylene
cis-l,2-Dichloroethylene
Nerve damage or thyroid problems
Discharge from steel/metal factories;
discharge from plastic and fertilizer
factories
Kidney, liver, or adrenal gland problems
Runoff from herbicide used on row
crops
Minor kidney changes
Runoff from herbicide used on rights
of way
Reproductive difficulties; increased risk
of cancer
Runoff/leaching from soil fumigant
used on soybeans, cotton, pineapples,
and orchards
Liver, kidney, or circulatory system
problems
Discharge from industrial chemical
factories
Anemia; liver, kidney or spleen damage;
changes in blood
Discharge from industrial chemical
factories
Increased risk of cancer
Discharge from industrial chemical
factories
Discharge from industrial chemical
factories
Discharge from industrial chemical
factories
Discharge from industrial chemical
factories
Liver problems; increased risk of cancer
Discharge from drug and chemical
factories
Increased risk of cancer
Discharge from industrial chemical
factories
Weight loss, liver problems, or possible
reproductive difficulties
Discharge from chemical factories
Reproductive difficulties; liver problems;
increased risk of cancer
Discharge from rubber and chemical
factories
Reproductive difficulties
Runoff from herbicide used on soybeans
and vegetables
Reproductive difficulties; increased risk
of cancer
Emissions from waste incineration
and other combustion; discharge
from chemical factories
Runoff from herbicide use
Public Health
Goal (mg/L)2
0.07
0.2
0.075
0.07
0.4
0.007
Stomach and intestinal problems
Runoff from herbicide use
Liver problems
Residue of banned insecticide
Increased cancer risk; stomach problems
Discharge from industrial chemical
factories; an impurity of some water
treatment chemicals
Liver or kidney problems
Discharge from petroleum refineries
0.7
Problems with liver, stomach, reproductive
system, or kidneys; increased risk of cancer
Discharge from petroleum refineries
Fecal coliforms andE. coll are bacteria whose
presence indicates that the water may be contaminated
with human or animal wastes. Microbes in these wastes
may cause short term effects, such as diarrhea, cramps,
nausea, headaches, or other symptoms. They may pose a
special health risk for infants, young children, and people
with severely compromised immune systems.
Human and animal fecal waste
lone 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
Short-term exposure: Gastrointestinal illness
(e.g., diarrhea, vomiting, cramps)
Human and animal fecal waste
Kidney problems; reproductive
difficulties
Runoff from herbicide use
Increased risk of cancer
Byproduct of drinking water
disinfection
Liver damage; increased risk of cancer
Residue of banned termiticide
Liver damage; increased risk of cancer
Breakdown of heptachlor
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
4.0
0.7
n/a
Disinfectant
| Disinfection Byproduct
| Inorganic Chemical
Microorganism
| Organic Chemical
Radionuclides
-------
Contaminant
MCLor
TT1 (mg/L)2
Potential health effects from
long-term3 exposure above the MCL
Common sources of contaminant
in drinking water
Legionella
Lindane
Mercury (inorganic)
Liver or kidney problems; reproductive
difficulties; increased risk of cancer
Discharge from metal refineries and
agricultural chemical factories
Kidney or stomach problems
Discharge from chemical factories
Infants and children: Delays in physical or
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
Legionnaire's Disease, a type of
pneumonia
Found naturally in water; multiplies in
heating systems
Liver or kidney problems
Runoff/leaching from insecticide used
on cattle, lumber, gardens
Kidney damage
Erosion of natural deposits; discharge
from refineries and factories;
runoff from landfills and croplands
Reproductive difficulties
Runoff/leaching from insecticide used
on fruits, vegetables, alfalfa, livestock
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
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
Slight nervous system effects
Runoff/leaching from insecticide used
on apples, potatoes, and tomatoes
Liver or kidney problems; increased
cancer risk
Discharge from wood-preserving
factories
Liver problems
Herbicide runoff
Skin changes; thymus gland problems;
immune deficiencies; reproductive or
nervous system difficulties; increased
risk of cancer
Runoff from landfills; discharge of
waste chemicals
Increased risk of cancer
Erosion of natural deposits
Hair or fingernail loss; numbness in fingers
or toes; circulatory problems
Discharge from petroleum and metal refineries;
erosion of natural deposits; discharge
from mines
Problems with blood
Herbicide runoff
Liver, kidney, or circulatory system problems
Discharge from rubber and plastic
factories; leaching from landfills
Liver problems; increased risk of cancer
Discharge from factories and dry cleaners
Hair loss; changes in blood; kidney, intestine,
or liver problems
Leaching from ore-processing sites;
discharge from electronics, glass,
and drug factories
Nervous system, kidney, or liver problems
Discharge from petroleum factories
Public Health
Goal (mg/L)2
0.05
0.004
Coliforms are bacteria that indicate that other,
potentially harmful bacteria may be present.
See fecal coliforms andE. coll
Naturally present in the environment
Liver, kidney or central nervous system problems;
increased risk of cancer
Byproduct of drinking water disinfection
Kidney, liver, or thyroid problems;
increased risk of cancer
Runoff/leaching from insecticide used
on cotton and cattle
Liver problems
Residue of banned herbicide
Changes in adrenal glands
Discharge from textile finishing
factories
Liver, nervous system, or circulatory
problems
Discharge from metal degreasing
sites and other factories
Liver, kidney, or immune system
problems
Discharge from industrial chemical
factories
Liver problems; increased risk of cancer
Discharge from metal degreasing
sites and other factories
n/a9
0.05
0.07
0.003
Disinfectant
Disinfection Byproduct
| Inorganic Chemical
Microorganism
Organic Chemical
Radionuclides
-------
Contaminant
MCLor
TT1 (mg/L)2
Potential health effects from
long-term3 exposure above the MCL
Common sources of contaminant
in drinking water
Public Health
Goal (mg/L)2
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 short term symptoms such as
nausea, cramps, diarrhea, and associated headaches.
Soil runoff
Increased risk of cancer, kidney toxicity
Erosion of natural deposits
Increased risk of cancer
Leaching from PVC pipes; discharge
from plastic factories
Short-term exposure: Gastrointestinal illness
(e.g., diarrhea, vomiting, cramps)
Human and animal fecal waste
Nervous system damage
Discharge from petroleum factories;
discharge from chemical factories
10
Disinfectant
Disinfection Byproduct
| Inorganic Chemical
Microorganism
| Organic Chemical
Radionuclides
-------
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 Health effects are from long-term exposure unless specified as short-term exposure.
4 Each water system must certify annually, 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 percent dosed at 1 mg/L (or equivalent); Epichlorohydrin = 0.01 percent dosed at 20 mg/L
(or equivalent).
5 Lead and copper are regulated by a Treatment Technique that requires systems to control the
corrosiveness of their water. If more than 10 percent 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.
6 A routine sample that is fecal col if orm-positive or E. compositive triggers repeat samples-if any
repeat sample is total coliform-positive, the system has an acute MCL violation. A routine sample
that is total coliform-positive and fecal coliform-negative or E. co//-negative triggers repeat samples-if
any repeat sample is fecal coliform-positive or E. co//-positive, the system has an acute MCL violation.
See also Total Coliforms.
7 EPAs 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:
• Cryptosporidiunr. 99 percent removal for systems that filter. Unfiltered systems are required to
include Cryptosporidium in their existing watershed control provisions.
• Giardia lamblia: 99.9 percent removal/inactivation
• Viruses: 99.99 percent 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 nephelolometric turbidity unit (NTU), and samples for turbidity must be
less than or equal to 0.3 NTU in at least 95 percent of the samples in any month. Systems that use
filtration other than conventional or direct filtration must follow state limits, which must include turbidity
at no time exceeding 5 NTU.
• HPC: No more than 500 bacterial colonies per milliliter
• Long Term 1 Enhanced Surface V\foter Treatment; Surface water systems or ground water systems
under the direct influence of surface water serving fewer than 10,000 people must comply with the
applicable Long Term 1 Enhanced Surface V\foter Treatment Rule provisions (e.g. turbidity standards,
individual filter monitoring, Cryptosporidium removal requirements, updated watershed control
requirements for unfiltered systems).
• Long Term 2 Enhanced Surface V\foter Treatment; 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 storages facilities and to ensure that the systems maintain microbial
protection as they take steps to reduce the formation of disinfection byproducts. (Monitoring
start dates are staggered by system size. The largest systems (serving at least 100,000
people) will begin monitoring in October 2006 and the smallest systems (serving fewer than
10,000 people) will not begin monitoring until October 2008. After completing monitoring and
determining their treatment bin, systems generally have three years to comply with any additional
treatment requirements.)
• 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.
8 No more than 5.0 percent 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
E. coli. If two consecutive TC-positive samples, and one is also positive for E. coli or fecal coliforms,
system has an acute MCL violation.
9 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)
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National Secondary Drinking
Water Regulation
National Secondary Drinking Water Regulations are non-enforceable guidelines regarding
contaminants that may cause cosmetic effects (such as skin or tooth discoloration) or aes-
thetic 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, some states
may choose to adopt them as enforceable standards.
Contaminant
Aluminum
Chloride
Color
Copper
Corrosivity
Fluoride
Foaming Agents
Iron
Manganese
Odor
PH
Silver
Sulfate
Total Dissolved Solids
Zinc
Secondary Maximum Contaminant Level
0.05 to 0.2 mg/L
250 mg/L
15 (color units)
1.0 mg/L
noncorrosive
2.0 mg/L
0.5 mg/L
0.3 mg/L
0.05 mg/L
3 threshold odor number
6.5-8.5
0.10 mg/L
250 mg/L
500 mg/L
5 mg/L
For More Information
EPA's Safe Drinking Water Web site:
http://www.epa.gov/safewater/
EPA's Safe Drinking Water Hotline:
(800) 426-4791
To order additional posters or other
ground water and drinking water
publications, please contact the
National Service Center for
Environmental Publications at:
(800) 490-9198, or
email: nscep@bps-lmit.com.
United States
Environmental Protection
Agency
EPA816-F-09-004
May 2009
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