Drinking Water Quality Standards FAQ - Ontario

1.   What are drinking quality water standards?

Drinking water quality standards are legally enforceable limits on contaminants in drinking water. They are designed to protect public health by limiting the amount of specific contaminants allowed in drinking water. Under Ontario's Safe Drinking Water Act and the new Ontario Drinking-Water Quality Standards Regulation (O. Reg. 169/03), the province has established standards for numerous contaminants. Water supplied by drinking water systems subject to the Safe Drinking Water Act must legally meet these standards.

2. What contaminants do Ontario's drinking water quality standards cover?

Drinking water quality standards under O. Reg 169/03 cover three different types of contaminants:

Microbiological:

The province has set standards for E. coli, fecal coliforms and total coliforms. Under O. Reg. 169/03 these parameters should not be detectable in drinking water. This Regulation also prescribes numerical limits for general bacteria populations that may be present in drinking water.

Coliforms are bacteria common in the environment and come from human and animal waste. Although most are harmless, their presence may indicate that there are other harmful bacteria in the water.

In addition, some bacteria can have a wide range of adverse health impacts -- they may cause acute illnesses such as gastroenteritis, or they may be a serious public health risk. For example, the infiltration of E. coli 157/H7 bacteria into a municipal well was a cause of seven deaths in Walkerton, Ontario in May 2000.

Operators at drinking water treatment plants are required to test regularly for coliform bacteria. The disinfection of drinking water by chlorination is designed to eliminate harmful bacteria.

Other pathogens that can cause gastrointestinal illness include viruses and parasites such as giardia lamblia and cryptosporidium. These are not currently regulated under Ontario's drinking water quality standards.

Chemical:

The province has set numerical standards for both inorganic and organic chemicals. These standards are expressed in milligrams per litre (for example, 1.01 mg/l. for lead) as maximum concentrations allowed in drinking water.

Many of the chemical contaminants come from industrial discharges or agricultural runoff into the source water, and are not necessarily removed by drinking water treatment. These chemicals can cause health problems if, over a lifetime, they are consumed in drinking water at levels above these limits. Mercury, for example, can cause kidney damage. Some organic chemicals, such as the pesticide alachlor, may pose an increased risk of cancer.

The province has also set a numerical limit on total trihalomethanes. These chemicals are formed as a result of the chlorine treatment of drinking water and, at unacceptably high levels, can cause liver, kidney or central nervous system problems or increase the risk of cancer.

Radiological:

O. Reg. 169/03 prescribes numerical standards for natural and artificial radio nuclides. These standards are expressed as maximum allowable concentrations in becquerels per litre. Radiological contaminants include radio nuclides, such as radium 228, that result from the erosion of naturally-occurring deposits, or artificial radio nuclides, such as tritium, released into the water by nuclear power plants.

3.   Does Ontario have drinking water quality standards for problems like taste and odour?

Like many other jurisdictions, Ontario has not regulated cosmetic or aesthetic problems in drinking water such as taste and odour. Odour and taste, as well as colour and clarity, are considered to be aesthetic parameters, and not a risk to health. While the colour, taste or odour of drinking water may not have health effects, it is not desirable in drinking water.

4. How do contaminants find their way into drinking water sources?

Some contaminants found in drinking water sources may occur naturally, such as arsenic. The majority of contaminants are the result of human activities and come from industrial discharges, agricultural runoff, sewage treatment plant outflows, nuclear power plants and other sources of pollution.

Not only are such contaminants directly discharged into waterways, but they may also find their way into water from aerial deposition and other pathways. These contaminants are not necessarily eliminated when drinking water is treated. Although the province has set standards for 78 contaminants, there are many chemicals in raw water for which no standards have been set, and many that are not even monitored.

5. What contaminants are removed through drinking water treatments?

Raw water is treated by physical and chemical processes to remove contaminants. The standard treatments in Canada are coagulation, flocculation, sedimentation, followed by filtration and chlorination. Coagulation, flocculation, sedimentation and filtration remove dirt, bacteria, viruses and other impurities from the water.

The final treatment is the addition of chlorine to disinfect and eliminate any organisms that might have survived the filtration process. Although these treatments do reduce the contaminants in drinking water, they are not designed to remove organic or inorganic chemicals, or radiological contaminants. Chlorine itself can combine with naturally occurring organic material in the water to form trihalomethanes.

6.   What is the federal role in establishing drinking water quality standards in Canada?

In Canada, a Federal-Provincial-Territorial Committee on Drinking Water develops and recommends national drinking water guidelines. It includes representatives of federal, provincial and territorial departments of health and the environment. It reviews toxicological and epidemiological evidence, and then makes recommendations on adding new substances to the guidelines or revising old guidelines. The Federal-Provincial-Territorial Committee makes recommendations for drinking water standards based on a process known as risk assessment. Provinces and territories then decide which of the guidelines to adopt for their jurisdictions. The provinces and territories may choose to adopt them as guidelines or as enforceable drinking water standards.

7. How are drinking water quality standards set in Ontario?

For many years Ontario adopted the national guidelines as the Ontario Drinking Water Objectives. After the deaths at Walkerton in May 2000, the objectives were incorporated into enforceable regulatory standards.

Currently, recommendations from the federal-provincial-territorial process are reviewed by Ontario, and if they are considered appropriate, they are then included in revisions to the schedules in the Regulation.

8.  How can I find out if my drinking water meets current Ontario standards?

Under Ontario's Drinking-Water Systems Regulation (O.Reg 170/03), owners of drinking water systems are required to prepare annual reports. The results of all drinking water tests must be reported, including the total number of adverse results. A copy of the annual report prepared by your drinking water supplier must be given to you upon your request and without charge. It must also be provided to the office of every "designated facility" (such as schools or health care facilities) served by the drinking water system.

For large municipal residential systems serving more than 10,000 people, the annual reports must be available for free on a web site. on the Internet. The water quality report of the City of Toronto, for example, may be found at: www.city.toronto.on.ca/water/quality_report.htm

You can also find more immediately available information on specific "adverse drinking water quality incidents" on the web site. of the Ministry of the Environment. Instances in which water quality standards in Ontario have been exceeded are listed according to region. However, the Ministry only reports health-related adverse water quality incidents involving high levels of E. coli or fecal coliforms, or where a boil water advisory or order has been issued. These incident reports can be found at:
www.ene.gov.on.ca/envision/adverse/adversewater.htm