EPA Thoughts
Microorganisms
| Contaminant |
MCLG1
(mg/L)2 |
MCL
or TT1
(mg/L)2 |
Potential
Health Effects from Ingestion of Water |
Sources
of Contaminant in Drinking Water |
| \Cryptosporidium\ |
zero
|
TT 3
|
Gastrointestinal
illness (e.g., diarrhea, vomiting, cramps) |
Human
and fecal animal waste |
| Giardia lamblia |
zero
|
|
Gastrointestinal
illness (e.g., diarrhea, vomiting, cramps) |
Human
and animal fecal waste |
| Heterotrophic plate count |
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) |
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
|
|
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. |
Soil
runoff |
| Viruses (enteric) |
zero
|
|
Gastrointestinal
illness (e.g., diarrhea, vomiting, cramps) |
Human
and animal fecal waste |
Disinfection Byproducts
| Contaminant |
MCLG1
(mg/L)2 |
MCL
or TT1
(mg/L)2 |
Potential
Health Effects from Ingestion of Water |
Sources
of Contaminant in Drinking Water |
| Bromate |
zero
|
0.010
|
Increased risk of
cancer |
Byproduct of drinking
water disinfection |
| Chlorite |
0.8
|
1.0
|
Anemia; infants &
young children: nervous system effects |
Byproduct of drinking
water disinfection |
| Haloacetic acids (HAA5) |
|
0.060
|
Increased risk of
cancer |
Byproduct of drinking
water disinfection |
| Total Trihalomethanes
(TTHMs) |
|
0.10
----------
0.080
|
Liver, kidney or
central nervous system problems; increased risk of cancer |
Byproduct of drinking
water disinfection |
Disinfectants
| Contaminant |
MRDLG1
(mg/L)2 |
MRDL1
(mg/L)2 |
Potential
Health Effects from Ingestion of Water |
Sources
of Contaminant in Drinking Water |
| Chloramines (as Cl2) |
MRDLG=41 |
MRDL=4.01 |
Eye/nose irritation;
stomach discomfort, anemia |
Water additive used
to control microbes |
| Chlorine (as Cl2) |
MRDLG=41 |
MRDL=4.01 |
Eye/nose irritation;
stomach discomfort |
Water additive used
to control microbes |
| Chlorine dioxide (as ClO2) |
MRDLG=0.81 |
MRDL=0.81 |
Anemia; infants &
young children: nervous system effects |
Water additive used
to control microbes |
Inorganic Chemicals
| Contaminant |
MCLG1
(mg/L)2 |
MCL
or TT1
(mg/L)2 |
Potential
Health Effects from Ingestion of Water |
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 |
|
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 & electronicsproduction
wastes |
Asbestos
(fiber >10 micrometers) |
7 million fibers
per liter
|
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
|
|
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 |
zero
|
|
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; leaching 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; leaching 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 |
Organic Chemicals
| Contaminant |
MCLG1
(mg/L)2 |
MCL
or TT1
(mg/L)2 |
Potential
Health Effects from Ingestion of Water |
Sources
of Contaminant in Drinking Water |
| Acrylamide |
zero
|
|
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
|
|
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 |
Radionuclides
| Contaminant |
MCLG1
(mg/L)2 |
MCL
or TT1
(mg/L)2 |
Potential
Health Effects from Ingestion of Water |
Sources
of Contaminant in Drinking Water |
| 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 |
| 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 |
| Radium 226
and Radium 228 (combined) |
|
5
pCi/L
|
Increased
risk of cancer |
Erosion
of natural deposits |
| Uranium |
zero
|
|
Increased risk
of cancer, kidney toxicity |
Erosion of
natural deposits |
Notes:
1Definitions:
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 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 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.
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 - 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.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 of1/1/02 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 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 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 is regulated with this group but has no MCLG.
-
Haloacetic acids:
dichloroacetic acid (zero); trichloroacetic acid (0.3 mg/L). Monochloroacetic
acid, bromoacetic acid, and dibromoacetic acid are regulated with this group
but have no MCLGs.
7 MCLGs were not established before the 1986 Amendments to the Safe Drinking Water
Act. 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 (using third-party
or manufacturer's certification) that when acrylamide and epichlorohydrin are
used in drinking water systems, the combination (or product) of dose and monomer
level does not exceed the levels specified, as follows:
National Secondary
Drinking Water Regulations
National
Secondary Drinking Water Regulations (NSDWRs or secondary 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. For more information, read Secondary Drinking
Water Regulations: Guidance for Nuisance Chemicals.
| Contaminant |
Secondary
Standard |
| Aluminum |
0.05
to 0.2 mg/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 |
| 
 |