# 35 Ill. Adm. Code 6200.620.410: Section 620.410 Groundwater Quality Standards for Class I: Potable Resource Groundwater

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URL: https://www.frixlaw.com/law-library/statutes/STATE_IL_IAC_T35_P6200_S620_410

## Section

- **Citation:** 35 Ill. Adm. Code 6200.620.410
- **Heading:** Section 620.410 Groundwater Quality Standards for Class I: Potable Resource Groundwater
- **Jurisdiction:** Illinois
- **Kind:** Regulations
- **Status:** In force
- **Text as of:** August 14, 2026
- **Source:** Compiled text
- **Location:** Illinois Administrative Code / Title 35  /  / Part 6200  / Section 620.410 Groundwater Quality Standards for Class I:  Potable Resource Groundwater

## Text

Section 620
TITLE 35: ENVIRONMENTAL PROTECTION
SUBTITLE F: PUBLIC WATER SUPPLIES
CHAPTER I: POLLUTION CONTROL BOARD
PART 620 GROUNDWATER QUALITY
SECTION 620.410 GROUNDWATER QUALITY STANDARDS FOR CLASS I: POTABLE RESOURCE GROUNDWATER
Section 620.410  Groundwater
Quality Standards for Class I:  Potable Resource Groundwater
a)         Inorganic Chemical Constituents
Except due to
natural causes or as provided in Section 620.450, concentrations of the
following chemical constituents must not be exceeded in Class I groundwater:
CASRN
Constituent
Standar
d
(mg/L)
a,b
7429-90-5
Aluminum
l.9
c
7440-36-0
Antimony
0.006
d
7440-38-2
Arsenic
e
0.01
d
7440-39-3
Barium
2.0
d
7440-41-7
Beryllium
0.004
d
7440-42-8
Boron
2.0
f
7440-43-9
Cadmium
0.005
d
16887-00-6
Chloride
200
g
7440-47-3
Chromium (total)
0.l
d
7440-48-4
Cobalt
0.0012
c
7440-50-8
Copper
0.5
h
143-33-9
Cyanide
0.2
d
7681-49-4
Fluoride
4
d
7439-89-6
Iron
5
g
7439-92-1
Lead
0.0075
i
7439-93-2
Lithium
0.04
j
7439-96-5
Manganese
0.l5
k
7487-94-7
Mercury (mercuric chloride)
0.002
d
7439-98-7
Molybdenum
0.308
c
7440-02-0
Nickel
0.077
c
14797-55-8
Nitrate as N
10
d
14797-73-0
Perchlorate
0.0081
c
7440-14-4
Radium (combined 226+228)
5
d
7782-49-2
Selenium
0.02
f
7440-22-4
Silver
0.058
c
14808-79-8
Sulfate
400
g
TDS (total dissolved solids)
1,200
g
7440-28-0
Thallium
0.002
d
7440-62-2
Vanadium
0.00027
c
7440-66-6
Zinc
l.2
c
Constituent Name and Groundwater
Quality Standard Notations
a
The
standard unit for radium (combined 226+228) is picocuries per liter (pCi/L).
b
The
inorganic groundwater quality standards are based on total metal analyses for
the evaluation of human health effects.
c
The
standard is calculated using the Human Threshold Toxicant Advisory
Concentration (HTTAC) procedures at Appendix A.
d
The
standard is based on the Maximum Contaminant Level (MCL), promulgated by USEPA,
Office of Water, and Illinois Primary Drinking Water Standards specified in 35
Ill. Adm. Code 611
y standards are based on total metal analyses for
the evaluation of human health effects.
c
The
standard is calculated using the Human Threshold Toxicant Advisory
Concentration (HTTAC) procedures at Appendix A.
d
The
standard is based on the Maximum Contaminant Level (MCL), promulgated by USEPA,
Office of Water, and Illinois Primary Drinking Water Standards specified in 35
Ill. Adm. Code 611.
e
The
constituent meets the definition of a "carcinogen" in Section
620.110.
f
The
standard is based on beneficial use for irrigation of crops, per "Water
Quality Criteria", by National Academy of Sciences, incorporated by
reference in Section 620.125.
g
The
standard is the 95% confidence concentration stated in the Agency's "Integrated
Water Quality Report and Section 303(d) List", incorporated by reference in
Section 620.125.
h
The
standard is based on beneficial use for watering livestock, per "Water
Quality Criteria", by National Academy of Sciences, incorporated by
reference in Section 620.125.
i
The
standard is 50% of the USEPA "action level" of 0.015 mg/L for lead.
The USEPA action level applies at the service connection.  The standard is
reduced by 50% as a safety margin, based on the assumption that 50% of water
would be treated.
j
The
standard is the "LLOQ" or "LCMRL" as defined in Section
620.110.
k
The standard is promulgated at 35 Ill. Adm. Code 611.300.
b)         Organic Chemical Constituents
Except due to
natural causes or as provided in Section 620.450 or subsection (c) of this
Section, concentrations of the following organic chemical constituents must not
be exceeded in Class I groundwater:
CASRN
Constituent
Standard (mg/L)
83-32-9
Acenaphthene
0.23
a
67-64-1
Acetone
3.5
a
15972-60-8
Alachlor
b
0.002
c
116-06-3
Aldicarb
0.003
c
120-12-7
Anthracene
1.2
a
319-84-6
alpha-
BHC
(
alpha-
benzene
hexachloride)
b
0.000012
d
71-43-2
Benzene
b
0.005
c
56-55-3
Benzo(a)anthracene
e
0.00025
d
205-99-2
Benzo(b)fluoranthene
e
0.00025
d
207-08-9
Benzo(k)fluoranthene
e
0.0025
d
50-32-8
Benzo(a)py
r:
CASRN
Constituent
Standard (mg/L)
83-32-9
Acenaphthene
0.23
a
67-64-1
Acetone
3.5
a
15972-60-8
Alachlor
b
0.002
c
116-06-3
Aldicarb
0.003
c
120-12-7
Anthracene
1.2
a
319-84-6
alpha-
BHC
(
alpha-
benzene
hexachloride)
b
0.000012
d
71-43-2
Benzene
b
0.005
c
56-55-3
Benzo(a)anthracene
e
0.00025
d
205-99-2
Benzo(b)fluoranthene
e
0.00025
d
207-08-9
Benzo(k)fluoranthene
e
0.0025
d
50-32-8
Benzo(a)pyrene
e
0.0002
c
65-85-0
Benzoic acid
15
a
78-93-3
2-Butanone (methyl ethyl
ketone)
2.3
a
1563-66-2
Carbofuran
0.04
c
75-15-0
Carbon disulfide
0.38
a
56-23-5
Carbon tetrachloride
b
0.005
c
12789-03-6
Chlordane
b
0.002
c
108-90-7
Chlorobenzene
0.l
c
67-66-3
Chloroform
b
0.07
f
218-01-9
Chrysene
e
0.025
d
94-75-7
2,4-D (2,4-dichlorophenoxy
acetic acid)
0.07
c
75-99-0
Dalapon
0.2
c
53-70-3
Dibenzo(a,h)anthracene
e
0.0001
g
96-12-8
1,2-Dibromo-3-chloropropane (dibromochloropropane)
e
0.0002
c
1918-00-9
Dicamba
0.12
a
95-50-1
o
-Dichlorobenzene (1,2-dichlorobenzene)
0.6
c
106-46-7
p
-Dichlorobenzene (1,4-dichlorobenzene)
b
0.075
c
75-71-8
Dichlorodifluoromethane
0.7
7
a
75-34-3
1,1-Dichloroethane
0.77
a
107-06-2
1,2-Dichloroethane
b
0.005
c
75-35-4
1,1-Dichloroethylene
0.007
c
156-59-2
cis
-1,2-Dichloroethylene
0.07
c
156-60-5
trans
-1,2-Dichloroethylene
0.l
c
75-09-2
Dichloromethane (methylene
chloride)
e
0.005
c
78-87-5
1,2-Dichloropropane
b
0.005
c
117-81-7
Di(2-ethylhexyl)phthalate
b
0.006
c
84-66-2
Diethyl phthalate
3.1
a
84-74-2
Di-
n
-butyl phthalate
0.38
a
99-65-0
1,3-Dinitrobenzene
0.001
g
121-14-2
2,4-Dinitrotoluene
b
0.001
g
606-20-2
2,6-Dinitrotoluene
b
0.0001
g
88-85-7
Dinoseb
0.007
c
123-91-1
1,4-Dioxane (
p
-dioxane)
b
0.00078
d
145-73-3
Endothall
0.l
c
72-20-8
Endrin
0.002
c
100-41-4
Ethylbenzene
b
0.7
c
106-93-4
Ethylene dibromide (1,2-dibromoethane)
b
0.00005
c
206-44-0
Fluoranthene
0.15
a
86-73-7
Fluorene
0.15
a
58-89-9
gamma-
HCH (
gamma-
Hexachlorocyclohexane,
lindane)
b
0.0002
c
13252-13-6
HFPO-DA (hexafluoropropylene
oxide dimer acid GenX)
0.000010
c
2691-41-0
HMX (octahydro-1,3,5,7-tetranitro-1,3,5
b
0.00078
d
145-73-3
Endothall
0.l
c
72-20-8
Endrin
0.002
c
100-41-4
Ethylbenzene
b
0.7
c
106-93-4
Ethylene dibromide (1,2-dibromoethane)
b
0.00005
c
206-44-0
Fluoranthene
0.15
a
86-73-7
Fluorene
0.15
a
58-89-9
gamma-
HCH (
gamma-
Hexachlorocyclohexane,
lindane)
b
0.0002
c
13252-13-6
HFPO-DA (hexafluoropropylene
oxide dimer acid GenX)
0.000010
c
2691-41-0
HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine)
0.77
a
76-44-8
Heptachlor
b
0.0004
c
1024-57-3
Heptachlor epoxide
b
0.0002
c
77-47-4
Hexachlorocyclopentadiene
0.05
c
193-39-5
Indeno(l,2,3-c,d)pyrene
e
0.00025
d
98-82-8
Isopropylbenzene (cumene)
b
0.38
a
93-65-2
MCPP (mecoprop)
0.1
g
1634-04-4
MTBE (methyl tertiary-butyl
ether)
0.038
a
72-43-5
Methoxychlor
0.04
c
90-12-0
1-Methylnaphthalene
0.27
a
91-57-6
2-Methylnaphthalene
0.015
c
95-48-7
2-Methylphenol (
o
-cresol)
0.19
a
91-20-3
Naphthalene
0.077
a
98-95-3
Nitrobenzene
0.0077
a
1336-36-3
PCBs (polychlorinated
biphenyls as decachloro-biphenyl)
b
0.0005
c
375-73-5
PFBS (perfluorobutanesulfonic
acid)
0.002
c
355-46-4
PFHxS (perfluorohexanesulfonic
acid)
0.000010
c
375-95-1
PFNA (perfluorononanoic acid)
0.000010
c
335-67-1
PFOA (perfluorooctanoic acid)
b
0.000004
bc
1763-23-1
PFOS (perfluorooctanesulfonic
acid)
0.000004
bc
87-86-5
Pentachlorophenol
0.00
1
c
108-95-2
Phenol
0.1
h
1918-02-1
Picloram
0.5
c
129-00-0
Pyrene
0.12
a
121-82-4
RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine)
0.062
a
122-34-9
Simazine
0.004
c
100-42-5
Styrene
0.l
c
118-96-7
TNT (2,4,6-trinitrotoluene)
0.0077
a
93-72-1
2,4,5-TP (silvex)
0.05
c
127-18-4
Tetrachloroethylene
b
0.005
c
108-88-3
Toluene
1
c
8001-35-2
Toxaphene
b
0.003
c
120-82-1
1,2,4-Trichlorobenzene
0.07
c
71-55-6
1,1,1-Trichloroethane
0.2
c
79-00-5
1,1,2-Trichloroethane
0.005
c
79-01-6
Trichloroethylene
e
0.005
c
75-69-4
Trichlorofluoromethane
1.2
a
99-35-4
1,3,5-Trinitrobenzene
0.46
a
75-01-4
Vinyl chloride
e
0.002
c
1330-20-7
Xylenes
10
c
Constituent Name and Groundwater
Quality Standard Notations
a
The
standard is the Human Threshold Toxicant Advisory Concent
82-1
1,2,4-Trichlorobenzene
0.07
c
71-55-6
1,1,1-Trichloroethane
0.2
c
79-00-5
1,1,2-Trichloroethane
0.005
c
79-01-6
Trichloroethylene
e
0.005
c
75-69-4
Trichlorofluoromethane
1.2
a
99-35-4
1,3,5-Trinitrobenzene
0.46
a
75-01-4
Vinyl chloride
e
0.002
c
1330-20-7
Xylenes
10
c
Constituent Name and Groundwater
Quality Standard Notations
a
The
standard is the Human Threshold Toxicant Advisory Concentration (HTTAC),
calculated using procedures specified in Appendix A.
b
The
constituent meets the definition of a "carcinogen" in Section
620.110.
c
The
standard is based on the Maximum Contaminant Level (MCL), promulgated by USEPA,
Office of Water, and Illinois Primary Drinking Water Standards in 35 Ill. Adm.
Code 611.
d
The
standard is the Human Nonthreshold Toxicant Advisory Concentration
("HNTAC"), calculated using procedures specified in Appendix A.
e
The
constituent meets the definition of a "mutagen" in Section 620.110.
f
The
standard is based on the Maximum Contaminant Level Goal ("MCLG"),
promulgated by USEPA, Office of Water.
g
The
standard is the "LLOQ" or "LCMRL" as defined in Section
620.110.
h
The
standard is based on 35 Ill. Adm. Code 302.208.
c)         Complex Organic Chemical Mixtures
1)         Concentrations of the following chemical constituents must not
be exceeded in Class I groundwater:
CASRN
Constituent
Standard (mg/L)
71-43-2
Benzene
a
0.005
b
Total BETX
11.705
c
Constituent Name and Groundwater
Quality Standard Notations
a
The
constituent meets the definition of a "carcinogen" in Section
620.110.
b
The
standard is based on the Maximum Contaminant Level (MCL), promulgated by USEPA,
Office of Water, and Illinois Primary Drinking Water Standards at 35 Ill. Adm.
Code 611.
c
The
standard is the total combined standard of benzene, ethylbenzene, toluene, and
xylenes.
2)         Atrazine
and Metabolites
Concentrations of the following
chemical constituents must not be exceeded in Class I groundwater
andard is based on the Maximum Contaminant Level (MCL), promulgated by USEPA,
Office of Water, and Illinois Primary Drinking Water Standards at 35 Ill. Adm.
Code 611.
c
The
standard is the total combined standard of benzene, ethylbenzene, toluene, and
xylenes.
2)         Atrazine
and Metabolites
Concentrations of the following
chemical constituents must not be exceeded in Class I groundwater.
CASRN
Constituent
Standard (mg/L)
1912-24-9
Atrazine
0.003
a
Total Atrazine and Metabolites
0.003
6190-65-4
DEA (desethyl-atrazine)
1007-28-9
DIA (desisopropyl-atrazine)
3397-62-4
DACT (diaminochlorotriazine)
Groundwater Quality Standard
Notation
a
The standard is based on the Maximum Contaminant Level
(MCL), promulgated by USEPA, Office of Water, and Illinois Primary Drinking
Water Standards at 35 Ill. Adm. Code 611.
d)         pH
Except due to
natural causes, a pH range of 6.5 - 9.0 units must not be exceeded in Class I
groundwater.
e)         Beta Particle and Photon Radioactivity
1)         Except due to natural causes, the average annual concentration
of beta particle and photon radioactivity from man-made radionuclides must not
exceed a dose equivalent to the total body or any internal organ greater than 4
mrem/year in Class I groundwater. If two or more radionuclides are present, the
sum of their dose equivalent to the total body or any internal organ must not
exceed 4 mrem/year in Class I groundwater except due to natural causes.
2)         Except for the radionuclides specified in subsection (e)(3),
the concentration of man-made radionuclides causing 4 mrem total body or organ
dose equivalent must be calculated on the basis of a 2 liter per day drinking
water intake using the 168-hour data in compliance with the procedure specified
in NCRP Report Number 22, incorporated by reference in Section 620.125(a)
tural causes.
2)         Except for the radionuclides specified in subsection (e)(3),
the concentration of man-made radionuclides causing 4 mrem total body or organ
dose equivalent must be calculated on the basis of a 2 liter per day drinking
water intake using the 168-hour data in compliance with the procedure specified
in NCRP Report Number 22, incorporated by reference in Section 620.125(a).
3)         Except due to natural causes, the average annual concentration
assumed to produce a total body or organ dose of 4 mrem/year of the following
chemical constituents must not be exceeded in Class I groundwater:
CASRN
Constituent
Critical Organ
Standard (pCi/L)
10028-17-8
Tritium
Total Body
20,000
10098-97-2
Strontium-90
Bone Marrow
8.0
f)         No
facility that is subject to 35 Ill. Adm. Code 811 or 814 must comply with any
requirement or standard of those rules to the extent it incorporates or is
otherwise based on any of the following constituents or their standards under
this Section:
CASRN
Constituent
13252-13-6
HFPO-DA (hexafluoropropylene
oxide dimer acid GenX)
375-73-5
PFBS (perfluorobutanesulfonic
acid)
355-46-4
PFHxS (perfluorohexanesulfonic
acid)
375-95-1
PFNA (perfluorononanoic acid)
335-67-1
PFOA (perfluorooctanoic acid)
1763-23-1
PFOS (perfluorooctanesulfonic
acid)

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