Table 3 EPA regulations of drinking water contaminants.

From: US drinking water quality: exposure risk profiles for seven legacy and emerging contaminants

Contaminant group	Substance	MCL,^a MRDL^b or TT^c	Standard (mg/l)
Disinfectants	Chloramines (as Cl2)	MRDL	4.0
	Chlorine	MRDL	4.0
	Chlorine dioxide	MRDL	0.8
Disinfection by-products	Bromate	MCL	0.010
	Chlorite	MCL	1.0
	Haloacetic acids	MCL	0.060
	Total Trihalomethanes	MCL	0.080
Inorganic chemicals	Antimony	MCL	0.006
	Arsenic	MCL	0.010
	Asbestos	MCL	(fibers >10 micrometers) 7 million fibers per liter (MFL)
	Barium	MCL	2
	Beryllium	MCL	0.004
	Cadmium	MCL	0.005
	Chromium	MCL	0.1
	Copper	TT	^d; Action Level = 1.3
	Cyanide	MCL	0.2
	Fluoride	MCL	4.0
	Lead	TT	^e
	Mercury (inorganic)	MCL	0.002
	Nitrate	MCL	10
	Nitrite	MCL	1
	Selenium	MCL	0.05
	Thallium	MCL	0.002
Microorganisms	Cryptosporidium	TT	^f
	Fecal coliform & E. coli	MCL	^g
	Giardia lamblia	TT	^h
	Heterotrophic plate count	TT	ⁱ
	Legionella	TT	^j
	Total Coliforms	MCL	5.0%^k
	Turbidity	TT	^l
	Viruses	TT	^m
Organic chemicals	Acrylamide	TT	ⁿ
	Alachlor	MCL	0.002
	Atrazine	MCL	0.003
	Benzene	MCL	0.005
	Benzo(a)pyrene (PAHs)	MCL	0.0002
	Carbofuran	MCL	0.04
	Carbon tetrachloride	MCL	0.005
	Chlordane	MCL	0.002
	Chlorobenzene	MCL	0.1
	2,4-D	MCL	0.07
	Dalapon	MCL	0.2
	1,2-Dibromo-3- chloropropane (DBCP)	MCL	0.0002
	o-Dichlorobenzene	MCL	0.6
	p-Dichlorobenzene	MCL	0.075
	1,2-Dichloroethane	MCL	0.005
	1,1-Dichloroethylene	MCL	0.007
	cis-1,2- Dichloroethylene	MCL	0.07
	trans-1,2, Dichloroethylene	MCL	0.1
	Dichloromethane	MCL	0.005
	1,2-Dichloropropane	MCL	0.005
	Di(2-ethylhexyl) adipate	MCL	0.4
	Di(2-ethylhexyl) phthalate	MCL	0.006
	Dinoseb	MCL	0.007
	Dioxin (2,3,7,8-TCDD)	MCL	0.00000003
	Diquat	MCL	0.02
	Endothall	MCL	0.1
	Endrin	MCL	0.002
	Epichlorohydrin	TT	^o
	Ethylbenzene	MCL	0.7
	Ethylene dibromide	MCL	0.00005
	Glyphosate	MCL	0.7
	Heptachlor	MCL	0.0004
	Heptachlor epoxide	MCL	0.0002
	Hexachlorobenzene	MCL	0.001
	Hexachlorocyclopentadiene	MCL	0.05
	Lindane	TT	0.0002
	Methoxychlor	MCL	0.04
	Oxamyl (Vydate)	MCL	0.2
	Pentachlorophenol	MCL	0.001
	Picloram	MCL	0.5
	Polychlorinated biphenyls (PCBs)	MCL	0.0005
	Simazine	MCL	0.004
	Styrene	MCL	0.1
	Tetrachloroethylene	MCL	0.005
	Toluene	MCL	1
	Toxaphene	MCL	0.003
	2,4,5-TP (Silvex)	MCL	0.05
	1,2,4- Trichlorobenzene	MCL	0.07
	1,1,1- Trichloroethane	MCL	0.2
	1,1,2- Trichloroethane	MCL	0.005
	Trichloroethylene	MCL	0.005
	Vinyl chloride	MCL	0.002
	Xylenes (total)	MCL	10
Radionuclides	Alpha/photon emitters	MCL	15 picocuries per Liter (pCi/L)
	Beta photon emitters	MCL	4 millirems per year
	Radium 226 and Radium 228 (combined)	MCL	5 pCi/l
	Uranium	MCL	30 µg/l

^aMCL: Maximum Contaminant Level. The highest level of a contaminant that is allowed in drinking water. MCLs are set as close to Maximum Contaminant Level Goals (MCLGs) as feasible using the best available treatment technology and taking cost into consideration. MCLs are enforceable standards.
^bMRDL: Maximum Residual Disinfectant Level. The highest level of a disinfectant allowed in drinking water.
^cTT: Treatment Technique. A required process intended to reduce the level of a contaminant in drinking water.
^dTT for copper requires systems to control the corrosiveness of their water. If more than 10 percent of tap water samples exceed the action level of 1.3 mg/L, water systems must take additional steps.
^eTT for lead requires systems to control the corrosiveness of their water. If more than 10 percent of tap water samples exceed the action level of 0.015 mg/L, water systems must take additional steps.
^f99% removal for systems that filter. Unfiltered systems are required to include Cryptosporidium in their existing watershed control provisions.
^gA routine sample that is fecal coliform-positive or E. coli-positive triggers repeat samples. If any repeat sample is total coliform-positive, the system has an acute MCL violation. A routine sample that is total coliform-positive and fecal coliform-negative or E. coli negative triggers repeat samples.
^h99.9 percent removal/inactivation.
ⁱNo more than 500 bacterial colonies per milliliter.
^jNo limit.
^kNo more than 5.0 percent samples total coliform-positive in a month.
^lFor systems that use conventional or direct filtration, at no time can turbidity exceed 1 nephelometric turbidity unit (NTU), and samples for turbidity must be less than or equal to 0.3 NTU in at least 95 percent of the samples in any month. Systems that use filtration other than the conventional or direct filtration must follow state limits, which must include turbidity at no time exceeding 5 NTU.
^m99.9 percent removal/inactivation.
ⁿEach water system must certify annually, in writing, to the state (using third-party or manufacturers certification) that when it uses acrylamide and/or epichlorohydrin to treat water, the combination (or product) of dose and monomer level does not exceed the levels specified, as follows: Acrylamide = 0.05 percent dosed at 1 mg/L (or equivalent); Epichlorohydrin = 0.01 percent dosed at 20 mg/L (or equivalent).
^oEach water system must certify annually that when it uses acrylamide and/or epichlorohydrin to treat water, the combination (or product) of dose and monomer level does not exceed the levels specified, as follows: Acrylamide = 0.05 percent dosed at 1 mg/L (or equivalent); Epichlorohydrin = 0.01 percent dosed at 20 mg/L (or equivalent).

Back to article page

Table 3 EPA regulations of drinking water contaminants.

Search

Quick links