1. A. With the exception of nitrate, nitrite, and total nitrate plus nitrite, all inorganic chemical contaminant levels are based on potential adverse health effects resulting from long term exposure to the contaminant in drinking water. All suppliers of water to community water systems shall comply with the MCL for fluoride. All suppliers of water to community water systems and nontransient noncommunity water systems shall comply with the MCLs for arsenic, asbestos, barium, cadmium, chromium, mercury, selenium, antimony, beryllium, cyanide, and thallium. All suppliers of water to community water systems, nontransient noncommunity water systems, and transient noncommunity water systems shall comply with the MCLs for nitrate, nitrite, and total nitrate plus nitrite. Compliance with MCLs for inorganic chemicals is determined under Regulation .14 of this chapter. The following are maximum contaminant levels for inorganic chemicals:

   Contaminant	Maximum Contaminant Level (mg/l)1
   (1) Antimony	0.006
   (2) Arsenic	0.010
   (3) Asbestos	7 million fibers per liter (longer than 10 µm)
   (4) Barium	2
   (5) Beryllium	0.004
   (6) Cadmium	0.005
   (7) Chromium	0.1
   (8) Cyanide (as free cyanide)	0.2
   (9) Flouride	4.0
   (10) Mercury	0.002
   (11) Nitrate as nitrogen	10
   (12) Nitrite as nitrogen	1
   (13) Total nitrate plus nitrite	10
   (14) Selenium	0.05
   (15) Thallium	0.002

2. B. Notwithstanding §A(2) of this regulation, the MCL value of 0.05 milligrams per liter (mg/l) for arsenic applies to community water systems until January 22, 2006. Beginning January 23, 2006, this section is no longer applicable.

3. C. At the discretion of the Approving Authority, levels of nitrate and total nitrate plus nitrite not to exceed 20 milligrams/liter may be allowed in a noncommunity water system if the supplier of water demonstrates to the satisfaction of the Approving Authority that:

   1. (1) The water is not available to children under 6 months old;
   2. (2) The supplier will post a warning which indicates that levels of nitrate or total nitrate plus nitrite exceed 10 milligrams/liter and the potential health effects of exposure;
   3. (3) Adverse health effects do not result; and
   4. (4) The supplier notified county health officers and the Approving Authority annually of all nitrate or total nitrate plus nitrite levels that exceed 10 milligrams/liter.

¹Unless otherwise specified.

Authority: Environment Article, Title 9, Subtitles 2 and 4, Annotated Code of Maryland

Effective date: October 21, 1977 (4:22 Md. R. 1670)

Appendix E adopted effective January 27, 1978 (5:2 Md. R. 84)

Regulations .01, .06—.11, .15A, .19A and B, .20F, and .22 amended effective August 10, 1987 (14:16 Md. R. 1774)

Regulations .15G—P, .19E, .28—.33, and .35 adopted effective August 10, 1987 (14:16 Md. R. 1774)

Regulations .26, .27, and .34 adopted effective November 30, 1987 (14:24 Md. R. 2555)

Appendices A—E recodified as Regulation .36

Chapter recodified from COMAR 10.17.07 to COMAR 26.04.01

Chapter revised effective March 18, 1991 (18:5 Md. R. 596)

Regulation .01B amended effective December 21, 1992 (19:25 Md. R. 2208)

Regulation .03A amended effective December 21, 1992 (19:25 Md. R. 2208)

Regulation .04A amended effective December 21, 1992 (19:25 Md. R. 2208)

Regulation .05-2 adopted effective December 21, 1992 (19:25 Md. R. 2208)

Regulation .08 amended effective December 21, 1992 (19:25 Md. R. 2208)

Regulation .10 repealed and new Regulation .10 adopted effective December 21, 1992 (19:25 Md. R. 2208)

Regulation .11 repealed and new Regulation .11 adopted effective December 21, 1992 (19:25 Md. R. 2208)

Regulation .11-1—.11-3 adopted effective December 21, 1992 (19:25 Md. R. 2208)

Regulation .12 amended effective December 21, 1992 (19:25 Md. R. 2208)

Regulation .17 amended effective December 21, 1992 (19:25 Md. R. 2208)

Regulation .20A, F amended effective December 21, 1992 (19:25 Md. R. 2208)

Regulation .33 amended effective December 21, 1992 (19:25 Md. R. 2208)

Chapter revised effective January 2, 1995 (21:26 Md. R. 2192)

Regulation .01B amended effective October 4, 1999 (26:20 Md. R. 1548); October 16, 2000 (27:20 Md. R. 1842)

Regulation .03A amended effective October 16, 2000 (27:20 Md. R. 1842)

Regulation .04 amended effective October 16, 2000 (27:20 Md. R. 1842)

Regulation .12 amended effective October 16, 2000 (27:20 Md. R. 1842)

Regulation .15 amended effective October 16, 2000 (27:20 Md. R. 1842)

Regulation .15-1 amended effective October 16, 2000 (27:20 Md. R. 1842)

Regulation .15-2 amended effective October 16, 2000 (27:20 Md. R. 1842)

Regulation .20-1 amended effective October 16, 2000 (27:20 Md. R. 1842)

Regulation .20-2 adopted effective October 16, 2000 (27:20 Md. R. 1842)

Regulation .23C adopted effective October 16, 2000 (27:20 Md. R. 1842)

Regulation .29D adopted effective October 16, 2000 (27:20 Md. R. 1842)

Regulation .31 repealed effective October 16, 2000 (27:20 Md. R. 1842)

Regulation .36 adopted effective October 4, 1999 (26:20 Md. R. 1548)

Chapter revised as an emergency provision effective January 1, 2002 (29:4 Md. R. 415); revised permanently effective April 29, 2002 (29:8 Md. R. 702)

Chapter revised effective September 1, 2003 (30:17 Md. R. 1205)

Regulation .01B amended effective April 25, 2005 (32:8 Md. R. 743); December 14, 2009 (36:25 Md. R. 1956); August 29, 2016 (43:17 Md. R. 957)

Regulation .01-1 amended effective April 25, 2005 (32:8 Md. R. 743)

Regulation .01-1B amended effective December 14, 2009 (36:25 Md. R. 1956); March 7, 2011 (38:5 Md. R. 319); August 29, 2016 (43:17 Md. R. 957)

Regulation .03A amended effective August 29, 2016 (43:17 Md. R. 957)

Regulation .04A amended effective August 29, 2016 (43:17 Md. R. 957)

Regulation .05F adopted effective March 7, 2011 (38:5 Md. R. 319)

Regulation .05-2 amended effective April 25, 2005 (32:8 Md. R. 743)

Regulation .15-2I amended effective August 29, 2016 (43:17 Md. R. 957)

Regulation .05-2L adopted effective December 14, 2009 (36:25 Md. R. 1956)

Regulation .05-5 adopted effective March 7, 2011 (38:5 Md. R. 319)

Regulation .06-2 amended effective March 7, 2011 (38:5 Md. R. 319)

Regulation .07 amended effective December 14, 2009 (36:25 Md. R. 1956)

Regulation .07-1 amended effective December 14, 2009 (36:25 Md. R. 1956)

Regulation .08E amended effective April 25, 2005 (32:8 Md. R. 743)

Regulation .09C amended effective April 25, 2005 (32:8 Md. R. 743)

Regulation .10 amended effective August 29, 2016 (43:17 Md. R. 957)

Regulation .11 amended effective August 29, 2016 (43:17 Md. R. 957)

Regulation .11D adopted effective March 7, 2011 (38:5 Md. R. 319)

Regulation .11-1 amended effective August 29, 2016 (43:17 Md. R. 957)

Regulation .11-2 amended effective March 7, 2011 (38:5 Md. R. 319); August 29, 2016 (43:17 Md. R. 957)

Regulation .11-3D adopted effective March 7, 2011 (38:5 Md. R. 319)

Regulation .11-4 adopted effective August 29, 2016 (43:17 Md. R. 957)

Regulation .12 amended effective April 25, 2005 (32:8 Md. R. 743)

Regulation .15-2 amended effective April 25, 2005 (32:8 Md. R. 743); December 14, 2009 (36:25 Md. R. 1956); March 7, 2011 (38:5 Md. R. 319)

Regulation .17A amended effective March 7, 2011 (38:5 Md. R. 319)

Regulation .19D amended effective August 29, 2016 (43:17 Md. R. 957)

Regulation .19D, G amended effective March 7, 2011 (38:5 Md. R. 319)

Regulation .20 amended effective April 25, 2005 (32:8 Md. R. 743); December 14, 2009 (36:25 Md. R. 1956); March 7, 2011 (38:5 Md. R. 319)

Regulation .20-1 amended effective March 7, 2011 (38:5 Md. R. 319)

Regulation .20-2 amended effective March 7, 2011 (38:5 Md. R. 319)

Regulation .20C, D amended effective August 29, 2016 (43:17 Md. R. 957)

Regulation .20-2E amended effective December 14, 2009 (36:25 Md. R. 1956); August 29, 2016 (43:17 Md. R. 957)

Regulation .21 amended effective December 14, 2009 (36:25 Md. R. 1956); March 7, 2011 (38:5 Md. R. 319)

Regulation .21H amended effective August 29, 2016 (43:17 Md. R. 957)

Regulation .21I adopted effective August 29, 2016 (43:17 Md. R. 957)

Regulation .23 amended effective December 14, 2009 (36:25 Md. R. 1956)

Regulation .23C amended effective March 7, 2011 (38:5 Md. R. 319)

Regulation .25B amended effective December 14, 2009 (36:25 Md. R. 1956)

Regulation .25C amended effective April 25, 2005 (32:8 Md. R. 743)

Regulation .30B amended effective December 14, 2009 (36:25 Md. R. 1956)

Regulation .34 amended effective March 1, 2004 (31:4 Md. R. 318)