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List of Contaminants & their Maximum Contaminant Level (MCLs)
From:
U.S Environmental Protective Agency
Website:
http://www.epa.gov/safewater/mcl.html
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 |
Notes
1 Definitions:
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:
- Acrylamide = 0.05% dosed at 1 mg/L (or equivalent)
- Epichlorohydrin = 0.01% dosed at 20 mg/L (or equivalent)
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