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Study: Freshwater supply and demand in Canada

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1971 to 2005

Renewable water resources have declined in Southern Canada over the past three decades. From 1971 to 2004, water yield in Southern Canada, the area in which 98% of the population lives, fell by an average of 3.5 cubic kilometres a year.

This annual loss is equivalent to the water contained in 1.4 million Olympic-size swimming pools, and almost as much water as was supplied to Canada's entire residential population in 2005. This represents an overall loss of 8.5% of the water yield in Southern Canada over the 34-year period.

Trends in water yield for Southern Canada, 1971 to 2004

Canada's total annual renewable freshwater supply is about 3,470 cubic kilometres, roughly equivalent to the volume of Lake Huron. This water yield is the result of precipitation and melted ice that flow over and under the ground, eventually reaching our rivers and lakes.

Water yield is distributed unequally across the country. The Pacific Coastal drainage region has the highest water yield in the country, followed by the Newfoundland and Labrador drainage region. Drainage regions in the Prairies and north of the Prairies produce the least water.

Note to readers

This release is based on an analytical article titled "Freshwater supply and demand in Canada" in the 2010 edition of Human Activity and the Environment. The article provides information on Canada's freshwater supply as well as the demands placed on it. This article combines new research done within Statistics Canada with information from other sources, including other federal government departments, international bodies and scientific journals.

The supply of freshwater, or Canada's renewable freshwater resources, is represented by water yield. Water yield is the amount of freshwater derived from unregulated flow measurements for a given geographic area over a defined period of time and is an estimate of the renewable water. Southern Canada is delineated by the North-line which separates Canada into two regions based on 16 social, biotic, economic and climatic variables (see map). Southern Canada, the portion of Canada below this line, has an area of almost 2.6 million square kilometres, is home to the majority of Canadians, and is where most economic activity takes place.

Human Activity and the Environment publications bring together a collection of environmental statistics that paint a statistical portrait of Canada's environment. Special emphasis is given to the relationship of human activity to air, water, soil, plants and animals. In the past, each annual issue of Human Activity and the Environment began with a feature article on an environmental topic of concern to Canadians, followed by a compendium of statistical tables. Starting with this edition, the article and statistical tables are published separately, with the article continuing to be released annually.

Water yield is also distributed unequally throughout the year. In much of Canada, the bulk of the water yield comes in spring and declines greatly through the summer months. However, demand increases in the summer, and is highest in July and August.

Trends in water yield on the Prairies

From 1971 to 2004, the area that had the lowest water yield and the highest variability in water yield was the Prairies. This variability is of interest because a lack of predictability in the flows of renewable water resources affects economic activities, including agriculture.

Four drainage regions comprise most of the Prairies and stretch across the southern part of Alberta, Saskatchewan and Manitoba. The population of this area rose by 1.6 million between 1971 and 2006 to about 4.5 million.

Yet this collection of drainage regions received an average annual yield of renewable freshwater equivalent to 12% of the yield of the Great Lakes drainage region, 6% of the Maritime Coastal drainage region and 3% of the Pacific Coastal drainage region. Compared internationally, the renewable freshwater per unit area of the Prairies is less than that for either Australia or South Africa.

From 1971 to 2004, the water yield for the Prairies fell by 0.56 cubic kilometres a year. In perspective, this annual loss represents about 80% of the total volume of water that was produced by drinking water plants in this region in 2005.

Trends in water yield for the Prairies, 1971 to 2004

Industrial and agricultural water use

In 2005, Canadians withdrew about 42 cubic kilometres of water from the environment, roughly 1.2% of the total average water yield. More than 90% of this volume went to support economic activity, while about 9% was used directly by the residential sector.

The sector that withdrew the most water overall, by a considerable margin, was thermal-electric power generation. In 2005, it used almost 28 cubic kilometres of water, the bulk of which was returned to the environment within a short period of time.

The manufacturing sector, in second place, used almost 6 cubic kilometres of water, or about 14% of all water use. Manufacturing industries use water mainly for processing, cleaning and cooling, but water can also be added to the content of final products.

The agricultural sector was responsible for almost 5% of total water withdrawals in 2005, the bulk of which (84%) was used to irrigate crops. The remainder predominantly went to support livestock production.

Residential water use

Water withdrawals for the residential sector were the third largest overall with 9.0% of total water use, about 3.8 cubic kilometres, in 2005. This amount includes the water supplied by drinking water plants to households, as well as the water withdrawn from private wells.

Drinking water plants provided water to about 28 million Canadians in 2005. Roughly 88% of water processed was from surface water sources, while 12% was from groundwater. Canadians who do not receive water supplied by drinking water plants typically rely on wells, which are fed by groundwater. Overall, about 25% of Canadians rely on groundwater, though this percentage varies from region to region.

The population in the Saint John–St. Croix drainage region of New Brunswick is the most reliant on groundwater, whereas the population in the South Saskatchewan drainage region is the least.

Embedded water

Water is present in all aspects of our lives, and is embedded in the goods and services that we rely on. This embedded water, also referred to as "virtual" water content, refers to the water used to make a product, including in the generation of the energy used in manufacturing, as well as all the water in all the inputs used in production. Water is used both to satisfy the demands of Canada's domestic economy, and to produce goods for export.

Of all the water withdrawn by Canadians in 2005, 63% was used to satisfy internal domestic demand for goods and services, and the remaining 37% was used to produce goods for export.

Relationship between supply and demand

Monthly water yield is lowest in August, a month in which demand for water is typically high.

Looking at August 2005 as an example, more than 40% of the water yield in some Prairie drainage regions was withdrawn for use by farms, industry and households.

Similarly intense demand was present in the Great Lakes drainage region. The Great Lakes themselves, however, contain more than 6.5 times Canada's annual water yield. Therefore, low summertime water yield in that drainage region has less potential to impose a constraint on human activities.

The publication Human Activity and the Environment: Freshwater Supply and Demand in Canada, 2010 (16-201-X, free) is now available. From the Key resource module of our website under Publications, choose All subjects, then Environment. Print versions can also be ordered through Statistics Canada's National Contact Centre (toll-free 1-800-263-1136;

For more information, or to enquire about the concepts, methods or data quality of this release, contact the information officer (613-951-0297;, Environment Accounts and Statistics Division.

Table 1

Water use in Canada, by sector, 2005 
  Water use Share of total water use
  km3 %
Total, all sectors 42.1 100.0
Thermal-electric power generation 27.8 66.2
Manufacturing 5.7 13.6
Residential 3.8 9.0
Irrigation 1.6 3.9
Livestock 0.3 0.8
Commercial and institutional 1.1 2.7
Water treatment and distribution systems 1.0 2.3
Mining (except oil and gas) 0.5 1.1
Oil and gas extraction 0.2 0.5