WHO's Guidelines for Drinking-Water Quality

WHO's Guidelines for Drinking-water Quality, the international reference point for standard setting and drinking-water safety.

Element/ substance	Symbol/ formula	Normally found in fresh water/surface water/ground water	Health based guideline by the WHO
Aluminium	Al		0,2 mg/l
Ammonia	NH4	<>	No guideline
Antimony	Sb	<>	0.005 mg/l
Arsenic	As		0,01 mg/l
Asbestos			No guideline
Barium	Ba		0,3 mg/l
Berillium	Be	<>	No guideline
Boron	B	<>	0,3 mg/l
Cadmium	Cd	<>	0,003 mg/l
Chloride	Cl		250 mg/l
Chromium	Cr+3, Cr+6	<>	0,05 mg/l
Colour			Not mentioned
Copper	Cu		2 mg/l
Cyanide	CN-		0,07 mg/l
Dissolvedoxygen	O2		No guideline
Fluoride	F	<>	1,5 mg/l
Hardness	mg/lCaCO3		No guideline
Hydrogen sulfide	H2S		No guideline
Iron	Fe	0,5 - 50 mg/l	No guideline
Lead	Pb		0,01 mg/l
Manganese	Mn		0,5 mg/l
Mercury	Hg	<>	0,001 mg/l
Molybdenum	Mb	<>	0,07 mg/l
Nickel	Ni	<>	0,02 mg/l
Nitrate and nitrite	NO3, NO2		50 mg/l total nitrogen
Turbidity			Not mentioned
pH			No guideline
Selenium	Se	< <>	0,01 mg/l
Silver	Ag	5 – 50 μg/l	No guideline
Sodium	Na	<>	200 mg/l
Sulfate	SO4		500 mg/l
Inorganic tin	Sn		No guideline
TDS			No guideline
Uranium	U		1,4 mg/l
Zinc	Zn		3 mg/l

Organic compounds

Group	Substance			Formula	Health based guideline by the WHO
Chlorinated alkanes	Carbon tetrachloride			C Cl4	2 μg/l
	Dichloromethane			C H2 Cl2	20 μg/l
	1,1-Dichloroethane			C2 H4 Cl2	No guideline
	1,2-Dichloroethane			Cl CH2 CH2 Cl	30 μg/l
	1,1,1-Trichloroethane			CH3 C Cl3	2000 μg/l
Chlorinated ethenes	1,1-Dichloroethene			C2 H2 Cl2	30 μg/l
	1,2-Dichloroethene			C2 H2 Cl2	50 μg/l
	Trichloroethene			C2 H Cl3	70 μg/l
	Tetrachloroethene			C2 Cl4	40 μg/l
Aromatic hydrocarbons	Benzene			C6 H6	10 μg/l
	Toluene			C7 H8	700 μg/l
	Xylenes			C8 H10	500 μg/l
	Ethylbenzene			C8 H10	300 μg/l
	Styrene			C8 H8	20 μg/l
	Polynuclear Aromatic Hydrocarbons (PAHs)			C2 H3 N1 O5 P1 3	0.7 μg/l
Chlorinated benzenes	Monochlorobenzene (MCB)			C6 H5 Cl	300 μg/l
	Dichlorobenzenes (DCBs)		1,2-Dichlorobenzene (1,2-DCB)	C6 H4 Cl2	1000 μg/l
			1,3-Dichlorobenzene (1,3-DCB)	C6 H4 Cl2	No guideline
			1,4-Dichlorobenzene (1,4-DCB)	C6 H4 Cl2	300 μg/l
	Trichlorobenzenes (TCBs)			C6 H3 Cl3	20 μg/l
Miscellaneous organic constituents	Di(2-ethylhexyl)adipate (DEHA)			C22 H42 O4	80 μg/l
	Di(2-ethylhexyl)phthalate (DEHP)			C24 H38 O4	8 μg/l
	Acrylamide			C3 H5 N O	0.5 μg/l
	Epichlorohydrin (ECH)			C3 H5 Cl O	0.4 μg/l
	Hexachlorobutadiene (HCBD)			C4 Cl6	0.6 μg/l
	Ethylenediaminetetraacetic acid (EDTA)			C10 H12 N2 O8	200 μg/l
	Nitrilotriacetic acid (NTA)			N(CH2COOH)3	200 μg/l
	Organotins	Dialkyltins		R2 Sn X2	No guideline
		Tributil oxide (TBTO)		C24 H54 O Sn2	2 μg/l

Pesticides

Substance		Formula	Health based guideline by the WHO
Alachlor		C14 H20 Cl N O2	20 μg/l
Aldicarb		C7 H14 N2 O4 S	10 μg/l
Aldrin and dieldrin		C12 H8 Cl6/ C12 H8 Cl6 O	0.03 μg/l
Atrazine		C8 H14 Cl N5	2 μg/l
Bentazone		C10 H12 N2 O3 S	30 μg/l
Carbofuran		C12 H15 N O3	5 μg/l
Chlordane		C10 H6 Cl8	0.2 μg/l
Chlorotoluron		C10 H13 Cl N2 O	30 μg/l
DDT		C14 H9 Cl5	2 μg/l
1,2-Dibromo-3-chloropropane		C3 H5 Br2 Cl	1 μg/l
2,4-Dichlorophenoxyacetic acid (2,4-D)		C8 H6 Cl2 O3	30 μg/l
1,2-Dichloropropane		C3 H6 Cl2	No guideline
1,3-Dichloropropane		C3 H6 Cl2	20 μg/l
1,3-Dichloropropene		CH3 CHClCH2 Cl	No guideline
Ethylene dibromide (EDB)		Br CH2 CH2 Br	No guideline
Heptachlor and heptachlor epoxide		C10 H5 Cl7	0.03 μg/l
Hexachlorobenzene (HCB)		C10 H5 Cl7 O	1 μg/l
Isoproturon		C12 H18 N2 O	9 μg/l
Lindane		C6 H6 Cl6	2 μg/l
MCPA		C9 H9 Cl O3	2 μg/l
Methoxychlor		(C6H4OCH3)2CHCCl3	20 μg/l
Metolachlor		C15 H22 Cl N O2	10 μg/l
Molinate		C9 H17 N O S	6 μg/l
Pendimethalin		C13 H19 O4 N3	20 μg/l
Pentachlorophenol (PCP)		C6 H Cl5 O	9 μg/l
Permethrin		C21 H20 Cl2 O3	20 μg/l
Propanil		C9 H9 Cl2 N O	20 μg/l
Pyridate		C19H23ClN2O2S	100 μg/l
Simazine		C7 H12 Cl N5	2 μg/l
Trifluralin		C13 H16 F3 N3 O4	20 μg/l
Chlorophenoxy herbicides (excluding 2,4-D and MCPA)	2,4-DB	C10 H10 Cl2 O3	90 μg/l
	Dichlorprop	C9 H8 Cl2 03	100 μg/l
	Fenoprop	C9H7Cl3O3	9 μg/l
	MCPB	C11 H13 Cl O3	No guideline
	Mecoprop	C10H11ClO3	10 μg/l
	2,4,5-T	C8 H5 Cl3 O3	9 μg/l

Disinfectants and disinfectant by-products

Group	Substance				Formula	Health based guideline by the WHO
Disinfectants	Chloramines				NHnCl(3-n), where n = 0, 1 or 2	3 mg/l
	Chlorine				Cl2	5 mg/l
	Chlorine dioxide				ClO2	No guideline
	Iodine				I2	No guideline
Disinfectant by-products	Bromate				Br O3-	25 μg/l
	Chlorate				Cl O3-	No guideline
	Chlorite				Cl O2-	200 μg/l
	Chlorophenols	2-Chlorophenol (2-CP)			C6 H5 Cl O	No guideline
		2,4-Dichlorophenol (2,4-DCP)			C6 H4 Cl2 O	No guideline
		2,4,6-Trichlorophenol (2,4,6-TCP)			C6 H3 Cl3 O	200 μg/l
	Formaldehyde				HCHO	900 μg/l
	MX (3-Chloro-4-dichloromethyl-5-hydroxy-2(5H)-furanone)				C5 H3 Cl3 O3	No guideline
	Trihalomethanes		Bromoform		C H Br3	100 μg/l
			Dibromochloromethane		CH Br2 Cl	100 μg/l
			Bromodichloromethane		CH Br Cl2	60 μg/l
			Chloroform		CH Cl3	200 μg/l
	Chlorinated acetic acids			Monochloroacetic acid	C2 H3 Cl O2	No guideline
				Dichloroacetic acid	C2 H2 Cl2 O2	50 μg/l
				Trichloroacetic acid	C2 H Cl3 O2	100 μg/l
	Chloral hydrate (trichloroacetaldehyde)				C Cl3 CH(OH)2	10 μg/l
	Chloroacetones				C3 H5 O Cl	No guideline
	Halogenated acetonitriles			Dichloroacetonitrile	C2 H Cl2 N	90 μg/l
				Dibromoacetonitrile	C2 H Br2 N	100 μg/l
				Bromochloroacetonitrile	CH Cl2 CN	No guideline
				Trichloroacetonitrile	C2 Cl3 N	1 μg/l
	Cyanogen chloride				Cl CN	70 μg/l
	Chloropicrin				C Cl3 NO2	No guideline