This page has been archived on the Web

Information identified as archived is provided for reference, research or recordkeeping purposes. It is not subject to the Government of Canada Web Standards and has not been altered or updated since it was archived. Please contact us to request a format other than those available.

Water Pollution Control

In this Section:


Just as the quality of the water affects the use we make of it, the reverse is also true. Once we have used the water, we affect its quality. This circular process indicates that the traditional habit of discharging untreated sewage and chemical wastes directly into rivers, lakes, estuaries of oceans for eventual "assimilation" into the environment is no longer acceptable -- either technically of morally.

The explosion in human population and industrial activities, and the rate at which new chemicals and products are being developed and used pose a global environmental threat. The natural decay processes in water bodies can no longer cope with these loads.

The approach to controlling pollution depends on:

  • the type of pollutant: is it degradable? persistent? is it metal? pesticide? dioxen? PCB?
  • the source: does it come from an industrial pipe? a farmer's field? the atmosphere?
  • the effects: is it harming fish? birds? plants? humans?

Water Quality Objectives and Guidelines

There is no single measure that constitutes good water quality. For instance, water suitable for drinking can be used for irrigation, but water used for irrigation may not meet drinking water guidelines.

In Canada, governments use various measures to protect water quality, among them guidelines and objectives. The two measures are similar in that both describe how much of a substance we, as a society, will tolerate in water. But guidelines and objectives are arrived at and applied differently.

Water quality guidelines are scientifically determined and indicate the maximum allowable concentration of substances for a particular water use such as livestock watering or swimming. These national guidelines serve as the targets for environmental protection.

Water quality objectives, on the other hand, specify the concentrations of substances permissible for all intended water uses at a specific location on a lake, river, or estuary. The objectives are based on the water quality guidelines for the uses at that location, as well as on public input and socio-economic considerations.

Water quality guidelines and objectives not only protect water users nad the environment, they also promote sustainable water management strategies.

See also:Water Quality Objectives and Guidelines section.


Ideally, polluting contaminants should be prevented from entering the water. At the most, in some circumstances, they can be allowed only in low concentrations. All provinces and territories in Canada have pollution control regulations. In deciding which substances to control, and to determine their concentrations and how they may enter the environment, a number of questions have to be asked, including:

  • what are the sources, amounts and effects of various substances?
  • what happens to them and what do they do after they have entered the water? do they change? to what?
  • where do the substances end up?
  • can they be prevented from reaching the water body or removed by treatment?

An example of a substance successfully regulated to reduce pollution is the phosphate found in laundry detergents. The Canadian Environmental Protection Act (CEPA) regulates many substances that have a deleterious effect on the environment.


Technology can be used in many cases to reduce or eliminate substances that may be harmful to the environment. Sewage treatment plants, properly operated and maintained, are a means of removing many toxic substances from wastewater and returning the treated water to a river or lake without causing harm downstream. Water treatment plants can take river or lake water and make it fit for drinking.

But what happens when contaminants are not removed, even by the most modern water treatment methods? They may be present only in minuscule quantities, but because they are persistent, they can build up to very harmful levels. In such cases, we can protect future generations and the ecosystem as a whole in only one way: preventing the chemicals from entering the water system.

Be a Responsible Consumer

Something all of us, as individuals, can do to protect water quality and the environment is to recycle products that are not degradable such as glass, cans and motor oil. Many municipalities in Canada have recycling programs.

Choose non-hazardous products. Most household chemical products and pesticides sold in Canada have warning labels. These labels tell whether the product is flammable, poisonous, corrosive or explosive. Proper disposal of these products is important to ensure water quality is not affected.

See also: Water Quality section

Date modified: