WHO's drinking water standards 1993

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

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 P_{1 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

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

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 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