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Drinking Water Quality Guidelines

The following guidelines provided are Canadian, American, and the guidelines set forth by the World Health Organization (WHO).

Click on each underlined contaminant for a brief description and more information. Most information on contaminants has been adapted from the Guidelines for Canadian Drinking Water Quality Sixth Edition, 1996.

Selection of Maximum Limits Permissible in Drinking Water

The following table is a brief selection of some contaminants and physical conditions that may be present in drinking water. A dash (-) indicates that there is no information available regarding possible limits.

Units are in milligrams per liter (mg/L) unless otherwise noted. Milligrams per liter are equivalent to parts per million.

Contaminant Canadian Limits (mg/L)* US Limits (mg/L)** WHO Limits (mg/L)***
Aluminum  0.1  0.05 – 0.2  –
Antimony  0.006  0.006  0.018
Arsenic  0.010  0.010  0.01
Asbestos  –  7 million fibers per liter  –
Barium  1.00  2  0.7
Beryllium  –  0.004  –
Boron  5.00  –  0.5
Bromate  0.01  0.010  0.010
Cadmium  0.005  0.005  0.003
Calcium  200  –  –
Chloramines  3.0  4.0  3
Chloride  250  250  –
Chlorite  –  1.0  0.7
Chromium  0.050  0.1  0.05
Cobalt  –  –  –
Total Coliforms (including fecal coliform & E. coli)  0 CFU/100mL  5%  0 CFU/100mL
Copper  1.0  1.0  2
Cryptosporidium  –  0  1.3×10-5 (organisms per L)
Colour  15 TCU  –  15 TCU
Cyanide  0.2  0.2  0.07
Cyanobacteria (total microystins)  0.0015  –  0.001
Fluoride  1.5  2.0  1.5
Giardia lamblia  –  0  –
Gold  –  –  –
Hardness (as CaCo3)  75-150  –  –
Heterotrophic plate count  –  500 CFU/mL  –
Iron  0.3  0.3  –
Lanthanum  –  –  –
Lead  0.010  0  0.001
Legionella  –  0  –
Magnesium  50  –  –
Manganese  0.050  0.05  0.1
Mercury  0.001  0.002  0.001
Molybdenum  0.25  –  0.07
Nickel  –  –  0.020
Nitrate  45  10  50
Nitrite  –  1  3
Odour  inoffensive  –  –
pH  6.5-8.5  6.5 – 8.5  –
Phosphorus  0.010  –  –
Potassium  –  –  –
Scandium  –  –  –
Selenium  0.01  0.05  0.04
Silicon  –  –  –
Silver  0.050  0.10  –
Sodium  200  –  –
Strontium  –  –  –
Sulphate  500 250  500
Sulphide  –  –  –
Thallium  –  0.002  –
Titanium  –  –  –
Total Dissolved Solids (TDS)  500 500  –
Trichloroethylene (TCE)  0.005 0.005  –
Trihalomethanes (total)^^  0.1  0.08  1
Tungsten  –  –  0
Turbidity  0.3/1.00.1 NTU^^^  5 NTU  0
Uranium  0.02  0.03  0.009
Vanadium  –  –  –
Viruses (entric)  –  0  –
Zinc  5.0  5  –

This table represents only a selection of contaminants that are posted in the guidelines. A full list is available via the websites below.

* As per Canadian or BC Health Act Safe Drinking Water Regulation BC Reg 230/92, & Sch 120, 2001. Task force of the Canadian Council or Resource and Environment Ministers Guidelines for Canadian Drinking Water Quality, 1996. See their website for more information.

** As per the U.S. Environmental Protection Agency Drinking Water Standards. See their website for more information.

*** As per the WHO (1998) Guidelines for drinking water quality, 2nd edition. Geneva, World Health Organization. See their website for more information.

^ TCU = true colour unit

^^ Individual limits for some of the individual trihalomethanes & haloacetic acids:

  • Trihalomethanes: bromodichloromethane (zero); bromoform (zero); dibromochloromethane (0.06 mg/L). Chloroform is regulated with this group but has no MCLG.
  • Haloacetic acids: dichloroacetic acid (zero); trichloroacetic acid (0.3 mg/L). Monochloroacetic acid, bromoacetic acid, and dibromoacetic acid are regulated with this group but have no limits.

^^^ NTU = nephelometric turbidity unit. Based on conventional treatment/slow sand or diatomaceous earth filtration/membrane filtration.

Selection of Maximum Limits Permissible in Drinking Water of Pesticides

The following table is a brief selection of some pesticides, herbicides, and insecticides that may be present in drinking water. A dash (-) indicates that there is no information available regarding possible limits.

Units are in milligrams per liter (mg/L) unless otherwise noted. Milligrams per liter are equivalent to parts per million.

Contaminant Canadian Limits (mg/L)*   US Limits (mg/L)**  WHO Limits (mg/L)***
 aldicarb + metabolites  0.009  –  –
 aldrin + dieldrin  0.0007  –  0.0003
 atrazine + metabolites  0.005  0.005  –
 azinphos-methyl  0.03  –  –
 bendiocarb  0.04  –  –
 bromixynil  0.005  –  –
 carbaryl  0.09  –  –
 carbofuran  0.09  0.04  0.007
 chlorpyrifos  0.09  –  0.03
 cyanazine  0.01  –  –
 diazinon  0.02  –  –
 dicamba  0.12  –  –
 dimethoate  0.009  –  0.006
 dinoseb  0.02  0.007  –
 diquat  0.07  0.02  0.006
 diuron  0.15  –  –
 glyphosate  0.28  0.7  0.005
 malathion  0.19  –  0.0009
 methoxychlor  0.9  0.4  0.02
metolachlor  0.05  –  –
 metribuzin  0.08  –  –
 paraquat (as dichloride)  0.01  –  –
 parathion  0.05  –  0.010
 phorate  0.002  –  –
 picloram 0.19  0.5  –
simazine  0.01  0.004  –
 terbufos  0.001  –  –
 trifluralin  0.045  –  –

This table represents only a selection of contaminants that are posted in the guidelines. A full list is available via the websites below.

* As per Canadian or BC Health Act Safe Drinking Water Regulation BC Reg 230/92, & Sch 120, 2001. Task force of the Canadian Council or Resource and Environment Ministers Guidelines for Canadian Drinking Water Quality, 1996. See their website for more information.

** As per the U.S. Environmental Protection Agency Drinking Water Standards. See their website for more information.

*** As per the WHO (1998) Guidelines for drinking water quality, 2nd edition. Geneva, World Health Organization. See their website for more information.

Water Testing & Sampling

(from the Guidelines for Canadian Drinking Water Quality, Sixth Edition)

The frequency of sampling water depends on the quality of the source water, the number of water sources, the past frequency of unsatisfactory samples, the adequacy of treatment and the capacity of the treatment plant, the size and complexity of the distribution system, the practice of disinfection and the size of the population serviced. The following is offered as a guide:

Population Served : Number of Samples per Month

up to 5000 : 4

5000 to 90000 : 1 per 1000 population

more than 90000 : 90 + (1 per 10000 population)

Contaminant Details

More details can be found on a full list of contaminants by visiting Health Canada’s website.