WHO's drinking water standards 1993

WHO's Guidelines for Drinking-water Quality, set up in Geneva, 1993, are 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	< 0,2 mg/l (up to 0,3 mg/l in anaerobic waters)	No guideline
Antimony	Sb	< 4 μg/l	0.005 mg/l
Arsenic	As		0,01 mg/l
Asbestos			No guideline
Barium	Ba		0,3 mg/l
Berillium	Be	< 1 μg/l	No guideline
Boron	B	< 1 mg/l	0,3 mg/l
Cadmium	Cd	< 1 μg/l	0,003 mg/l
Chloride	Cl		250 mg/l
Chromium	Cr⁺³, Cr⁺⁶	< 2 μg/l	0,05 mg/l
Colour			Not mentioned
Copper	Cu		2 mg/l
Cyanide	CN^-		0,07 mg/l
Dissolved oxygen	O₂		No guideline
Fluoride	F	< 1,5 mg/l (up to 10)	1,5 mg/l
Hardness	mg/l CaCO₃		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	< 0,5 μg/l	0,001 mg/l
Molybdenum	Mb	< 0,01 mg/l	0,07 mg/l
Nickel	Ni	< 0,02 mg/l	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	0,01 mg/l
Silver	Ag	5 – 50 μg/l	No guideline
Sodium	Na	< 20 mg/l	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 H₂Cl₂	20 μg/l
	1,1-Dichloroethane			C₂H₄Cl₂	No guideline
	1,2-Dichloroethane			Cl CH₂CH₂Cl	30 μg/l
	1,1,1-Trichloroethane			CH₃C Cl₃	2000 μg/l
Chlorinated ethenes	1,1-Dichloroethene			C₂H₂Cl₂	30 μg/l
	1,2-Dichloroethene			C₂H₂Cl₂	50 μg/l
	Trichloroethene			C₂H Cl₃	70 μg/l
	Tetrachloroethene			C₂Cl₄	40 μg/l
Aromatic hydrocarbons	Benzene			C₆H₆	10 μg/l
	Toluene			C₇H₈	700 μg/l
	Xylenes			C₈H₁₀	500 μg/l
	Ethylbenzene			C₈H₁₀	300 μg/l
	Styrene			C₈H₈	20 μg/l
	Polynuclear Aromatic Hydrocarbons (PAHs)			C₂ H₃ N₁ O₅ P₁ ₃	0.7 μg/l
Chlorinated benzenes	Monochlorobenzene (MCB)			C₆H₅Cl	300 μg/l
	Dichlorobenzenes (DCBs)		1,2-Dichlorobenzene (1,2-DCB)	C₆H₄Cl₂	1000 μg/l
			1,3-Dichlorobenzene (1,3-DCB)	C₆H₄Cl₂	No guideline
			1,4-Dichlorobenzene (1,4-DCB)	C₆H₄Cl₂	300 μg/l
	Trichlorobenzenes (TCBs)			C₆H₃Cl₃	20 μg/l
Miscellaneous organic constituents	Di(2-ethylhexyl)adipate (DEHA)			C₂₂H₄₂O₄	80 μg/l
	Di(2-ethylhexyl)phthalate (DEHP)			C₂₄H₃₈O₄	8 μg/l
	Acrylamide			C₃H₅N O	0.5 μg/l
	Epichlorohydrin (ECH)			C₃H₅Cl O	0.4 μg/l
	Hexachlorobutadiene (HCBD)			C₄Cl₆	0.6 μg/l
	Ethylenediaminetetraacetic acid (EDTA)			C₁₀H₁₂N₂O₈	200 μg/l
	Nitrilotriacetic acid (NTA)			N(CH₂COOH)₃	200 μg/l
	Organotins	Dialkyltins		R₂Sn X₂	No guideline
		Tributil oxide (TBTO)		C₂₄H₅₄O Sn₂	2 μg/l

Pesticides

Substance		Formula	Health based guideline by the WHO
Alachlor		C₁₄H₂₀Cl N O₂	20 μg/l
Aldicarb		C₇H₁₄N₂O₄S	10 μg/l
Aldrin and dieldrin		C₁₂H₈Cl₆/ C₁₂H₈Cl₆O	0.03 μg/l
Atrazine		C₈H₁₄Cl N₅	2 μg/l
Bentazone		C₁₀H₁₂N₂O₃S	30 μg/l
Carbofuran		C₁₂H₁₅N O₃	5 μg/l
Chlordane		C₁₀H₆Cl₈	0.2 μg/l
Chlorotoluron		C₁₀H₁₃Cl N₂O	30 μg/l
DDT		C₁₄H₉Cl₅	2 μg/l
1,2-Dibromo-3-chloropropane		C₃H₅Br₂Cl	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 CH₂CH₂ Br	No guideline
Heptachlor and heptachlor epoxide		C₁₀H₅Cl₇	0.03 μg/l
Hexachlorobenzene (HCB)		C₁₀H₅ Cl₇ O	1 μg/l
Isoproturon		C₁₂ H₁₈N₂ O	9 μg/l
Lindane		C₆ H₆ Cl₆	2 μg/l
MCPA		C₉H₉Cl O₃	2 μg/l
Methoxychlor		(C₆H₄OCH₃)₂CHCCl₃	20 μg/l
Metolachlor		C₁₅ H₂₂ Cl N O₂	10 μg/l
Molinate		C₉H₁₇N 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	C₁₀H₁₀Cl₂O₃	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				NH_nCl^(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 H₄Cl₂O	No guideline
		2,4,6-Trichlorophenol (2,4,6-TCP)			C₆ H₃Cl₃ 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 H₃Cl O₂	No guideline
				Dichloroacetic acid	C₂ H₂ Cl₂ O₂	50 μg/l
				Trichloroacetic acid	C₂H 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