327 IAC 8-2-4 - Inorganic chemicals; maximum contaminant levels

Authority: IC 13-13-5; IC 13-14-8-7; IC 13-14-9; IC 13-18-3; IC 13-18-16

Affected: IC 13-18

Sec. 4.

(a) The following MCLs for inorganic chemicals apply to all CWSs, NTNCWSs, and TWSs except as provided in subsection (b):

Contaminant	Level in Milligrams Per Liter
Nitrate	10 (as nitrogen)
Nitrite	1 (as nitrogen)
Nitrate and nitrite	10 (as nitrogen)

(b) The commissioner may allow nitrate levels up to, but not to exceed, twenty (20) milligrams per liter in a noncommunity water system if the supplier of water meets all of the following conditions:

(1) Such water will not be available to children under six (6) months of age.

(2) There will be continuous posting of the fact that nitrate levels exceed ten (10) milligrams per liter and the potential health effects of exposure.

(3) Local and state public health authorities shall be notified annually of nitrate levels that exceed ten (10) milligrams per liter.

(4) No adverse health effects shall result.

(5) The commissioner may require additional notice to the public as provided by 327 IAC 8-2.1-14.

(c) The following MCL for fluoride applies to all CWSs:

Contaminant	Level in Milligrams Per Liter
Fluoride	4.0

(d) The following MCLs for inorganic chemicals apply to all CWSs and NTNCWSs:

valign="top" align="left">Level in Milligrams

Contaminant	Per Liter Except Asbestos
Antimony	0.006
Arsenic	0.0101
Asbestos	7 (MFL) 2
Barium	2
Beryllium	0.004
Cadmium	0.005
Chromium	0.1
Cyanide (free)	0.2
Mercury	0.002
Selenium	0.05
Thallium	0.002
1Effective January 1, 2006. Until then, the arsenic MCL is 0.05 mg/l.
2MFL = million fibers per liter greater than ten (10) micrometers.

(e) For the inorganic chemicals listed in this section and nickel, the monitoring frequency is specified in section 4.1 of this rule and analytical methods are specified in section 4.2 of this rule.

(f) The commissioner hereby identifies the following as the BAT, treatment technique, or other means available for achieving compliance with the MCLs for inorganic contaminants identified in subsections (a), (c), and (d), except fluoride:

BAT for Inorganic Chemicals Listed in This Section
Chemical Name	BATs
Antimony	2,7
Arsenic4	1, 2, 5, 6, 7, 9, 125
Asbestos	2,3,8
Barium	5,6,7,9
Beryllium	1,2,5,6,7
Cadmium	2,5,6,7
Chromium	2,5,62,7
Cyanide	5,7,10
Mercury	21,4,61,71
Nitrate	5,7,9
Nitrite	5,7
Selenium	1,23,6,7,9
Thallium	1,5

¹BAT only if influent mercury concentrations less than ten (10) micrograms per liter.

²BAT for Chromium III only.

³BAT for Selenium IV only.

⁴BATs for Arsenic V. Preoxidation may be required to convert Arsenic III to Arsenic V. Arsenic BATs apply beginning January 1, 2006.

⁵To obtain high removals, iron to arsenic ratio must be at least 20:1.

Key to BATs in Table

1 = Activated alumina

2 = Coagulation/filtration (not BAT for systems > 500 service connections)

3 = Direct and diatomite filtration

4 = Granular activated carbon

5 = Ion exchange

6 = Lime softening (not BAT for systems > 500 service connections)

7 = Reverse osmosis

8 = Corrosion control

9 = Electrodialysis

10 = Chlorine

11 = Ultraviolet

12 = Oxidation/filtration

(g) The commissioner, pursuant to Section 1412 of the Act, hereby identifies in the following table the affordable technology, treatment technique, or other means available to systems serving ten thousand (10,000) persons or fewer for achieving compliance with the MCL for arsenic that will be applicable beginning January 1, 2006:

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	501-3,300, 3,301-10,000
Coagulation-assisted microfiltration	501-3,300, 3,301-10,000
Electrodialysis reversal6	501-3,300, 3,301-10,000
Enhanced coagulation/filtration	All size categories
Enhanced lime softening (pH 10.5)	All size categories
Ion exchange	All size categories
Lime softening5	501-3,300, 3,301-10,000
Oxidation/filtration7	All size categories
Reverse osmosis (centralized)6	501-3,300, 3,301-10,000
Reverse osmosis (point-of-use)4	All size categories

¹Section 1412(b)(4)(E)(ii) of the Act specifies that SSCTs must be affordable and technically feasible for small systems.

²SSCTs for Arsenic V. Preoxidation may be required to convert Arsenic III to Arsenic V.

³The Act (ibid.) specifies three (3) categories of small systems as follows:

(A) Those serving twenty-five (25) or more, but fewer than five hundred one (501).

(B) Those serving more than five hundred (500), but fewer than three thousand three hundred one (3,301).

(C) Those serving more than three thousand three hundred (3,300), but fewer than ten thousand one (10,001).

⁴When POU or POE devices are used for compliance, programs to ensure proper long term operation, maintenance, and monitoring must be provided by the water system to ensure adequate performance.

⁵Unlikely to be installed solely for arsenic removal. May require pH adjustment to optimal range if high removals are needed.

⁶Technologies reject a large volume of water; may not be appropriate for areas where water quantity may be an issue.

⁷To obtain high removals, iron to arsenic ratio must be at least 20:1.

Notes

327 IAC 8-2-4

Water Pollution Control Board; 327 IAC 8-2-4; filed Sep 24, 1987, 3:00 p.m.: 11 IR 706; filed Dec 28, 1990, 5:10 p.m.: 14 IR 1006; filed Aug 24, 1994, 8:15 a.m.: 18 IR 22; filed Aug 25, 1997, 8:00 a.m.: 21 IR 34; filed Nov 20, 2001, 10:20 a.m.: 25 IR 1079; filed Jun 13, 2005, 2:30 p.m.: 28 IR 3188 Readopted filed 10/18/2024, 1:57 p.m.: 20241113-IR-327230810RFA