Illinois Administrative Code › Title 35 - ENVIRONMENTAL PROTECTION › Part 611 - PRIMARY DRINKING WATER STANDARDS › Subpart F - MAXIMUM CONTAMINANT LEVELS (MCLs) AND MAXIMUM RESIDUAL DISINFECTANT LEVELS (MRDLs) › Section 611.301 - Revised MCLs for Inorganic Chemical Contaminants

Current through Register Vol. 48, No. 28, July 12, 2024
a) This subsection corresponds with
				40 CFR
				141.62(a), reserved by
				USEPA. This statement maintains structural consistency with USEPA
				rules.
b) The MCLs in the following
				table apply to CWSs. Except for fluoride, the MCLs also apply to NTNCWSs. The
				MCLs for nitrate, nitrite, and total nitrate and nitrite also apply to
				transient non-CWSs.
Contaminant
MCL
Units
Antimony
0.006
mg/L
Arsenic
0.010
mg/L
Asbestos
7
MFL
Barium
2
mg/L
Beryllium
0.004
mg/L
Cadmium
0.005
mg/L
Chromium
0.1
mg/L
Cyanide (as free
							 CN-)
0.2
mg/L
Fluoride
4.0
mg/L
Mercury
0.002
mg/L
Nitrate (as N)
10
mg/L
Nitrite (as N)
1
mg/L
Total Nitrate and Nitrite (as N)
10
mg/L
Selenium
0.05
mg/L
Thallium
0.002
mg/L
BOARD NOTE: See Section
				  611.300(d) for
				  an elevated nitrate level for non-CWSs. USEPA removed and reserved the MCL for
				  nickel on June 29, 1995, at 60 Fed. Reg. 33932, as a result of a judicial order
				  in Nickel Development Institute v. EPA, No. 92-1407, and Specialty Steel
				  Industry of the U.S. v. Browner, No. 92-1410 (D.C. Cir. Feb. 23 & Mar. 6,
				  1995), while retaining the contaminant, analytical methodology, and detection
				  limit entries for this contaminant.
c) USEPA identifies specific treatment
				technologies as BAT for achieving compliance with the IOC MCLs, except for
				fluoride:
Contaminant
BATs
Antimony
C/F
RO
Arsenic (BATs for AsV.
							 Pre-oxidation may be required to convert AsIII to
							 AsV.)
AAL
C/F
IX
LIME
RO
ED
O/F (to obtain high removals, the iron to arsenic
							 ratio must be at least 20:1)
Asbestos
C/F
DDF
CC
Barium
IX
LIME
RO
ED
Beryllium
AA
C/F
IX
LIME
RO
Cadmium
C/F
IX
LIME
RO
Chromium
C/F
IX
LIME (for CrIII
							 only)
RO
Cyanide
IX
RO
ALK Cl2
Mercury
C/F (only if influent Hg concentrations less than or
							 equal to 10 µg/L)
GAC
LIME (only if influent Hg concentrations less than or
							 equal to 10 µg/L)
RO (only if influent Hg concentrations less than or
							 equal to 10 µg/L)
Nickel
IX
LIME
RO
Nitrate
IX
RO
ED
Nitrite
IX
RO
Selenium
AAL
C/F (for SeIV only)
LIME
RO
ED
Thallium
AAL
IX
Abbreviations
AAL
Activated alumina
ALK Cl2
Alkaline chlorination (pH [GREATER THAN OR EQUAL TO]
							 8.5)
C/F
Coagulation/filtration (not BAT for a system having
							 fewer than 500 service connections)
CC
Corrosion control
Cl2
Oxidation (chlorine)
DDF
Direct and diatomite filtration
ED
Electrodialysis
GAC
Granular activated carbon
IX
Ion exchange
LIME
Lime softening
O/F
Oxidation/filtration
RO
Reverse osmosis
UV
Ultraviolet irradiation
d)
				At 40 CFR
				141.62(d), USEPA identified
				the affordable technology, treatment technique, or other means available to
				systems serving 10,000 persons or fewer for achieving compliance with the MCL
				for arsenic:
Small System Compliance Technologies
							 (SSCTs)1 for
							 Arsenic2
Small system compliance technology
Affordable for listed small system
							 categories3
Activated alumina (centralized)
All size categories
Activated alumina
							 (point-of-use)4
All size categories
Coagulation/filtration5
501 to 3,300 persons,
3,301 to 10,000 persons
Coagulation-assisted microfiltration
501 to 3,300 persons,
3,301 to 10,000 persons
Electrodialysis
							 reversal6
501 to 3,300 persons,
3,301 to 10,000 persons
Enhanced coagulation/filtration
All size categories
Enhanced lime softening (pH >10.5)
All size categories
Ion exchange
All size categories
Lime softening5
501 to 3,300 persons,
3,301 to 10,000 persons
Oxidation/filtration7
All size categories
Reverse osmosis
							 (centralized)6
501 to 3,300 persons,
3,301 to 10,000 persons
Reverse osmosis
							 (point-of-use)4
All size categories
1 Section 1412(b)(4)(E)(i) through
				  (iii) of SDWA (42 U.S.C.
				  300g-1(b)(4)(E)(i) through
				  (iii)) specifies that SSCTs must be
				  affordable and technically feasible for a small system supplier.
2 SSCTs for
				  AsV. Pre-oxidation may be required to convert
				  AsIII to AsV.
3 SDWA specifies three categories
				  of small system suppliers: (1) those serving 25 or more, but fewer than 501
				  persons, (2) those serving more than 500 but fewer than 3,301 persons, and (3)
				  those serving more than 3,300 but fewer than 10,001 persons.
				  42 U.S.C.
				  300g-1(b)(4)(E)(ii).
4 When a supplier uses POU or POE
				  devices for compliance, the supplier must provide programs to ensure proper
				  long-term operation, maintenance, and monitoring to ensure adequate
				  performance.
5 A supplier will not likely
				  install this technology solely for arsenic removal. This technology may require
				  pH adjustment to optimal range to obtain high removals.
6 This technology rejects a large
				  volume of water and may not be appropriate for areas where water quantity is an
				  issue.
7 To obtain high removals using
				  this technology, the iron to arsenic ratio must be at least 20:1.
BOARD NOTE: This Section derives from
					 40 CFR
					 141.62.