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 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 P13 | 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 | ||||
