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Potable water volumes

Drinking water plants in Canada supplied 5,103 million cubic metres of potable water in 2011 (Tables 1-1 and 1-2). Surface water sources provided about 89% of the total volume, groundwater sources provided about 10%, and the remaining 1% came from groundwater under the direct influence of surface water (GUDI) ¹  sources.

Comparing the 2011 survey results to those from the last survey (2007), the total volume of potable water produced decreased by 9% from 5,617 million cubic metres, reflecting a trend of declining water use over the last decade. ²  The decline for groundwater and GUDI sources was more pronounced at 15% (combined) than it was for surface water sources at 8% (Chart 1). This reflects a trend away from using groundwater towards using surface water piped from larger lakes. ³ 

Chart 2 compares monthly volumes of potable water produced by drinking water plants in 2007 and 2011, showing that the seasonal fluctuations in both years are similar (Tables 1-3 and 1-4). ⁴  In 2011, volumes ranged between a low of 372 million cubic metres in February to a peak of 522 million cubic metres in July. Volumes for 2011 were 7% to 14% lower than in 2007.

Population served

In 2011, drinking water plants provided potable water to nearly 29 million Canadians (Tables 2-1 and 2-2). The majority of those (just over 25 million people) received drinking water drawn from surface water sources. Groundwater sources supplied nearly three and a half million people, while GUDI sources supplied just over 440,000 people. The remaining five and a half million Canadians either had their own water supply or received water from facilities outside the scope of the survey.

Between 2007 and 2011, the total population served by drinking water plants grew by three and a half percent, or nearly one million people. Surface water sources accommodated all of this growth; groundwater and GUDI sources experienced small declines in the number of people they supplied.

Treatment methods

Conventional plants and direct filtration plants produced 60% of potable water in 2011 (Table 3-1), up 5% from 2007. The share of the total population served by these plants increased by 7% to just over 19 million people, or 66% of the population served (Table 3-1). Conventional plants apply coagulation, flocculation, sedimentation and granular media filtration in the treatment process. The difference between conventional plants and direct filtration plants is that direct filtration plants do not include a sedimentation process. ⁵  Plants using unfiltered systems that disinfect only, or disinfect and use other non-filtration processes, served 16% of the population. Plants using membrane filtration systems served 8% of the population and another 8% of the population was served by plants with other types of filtration systems. The remaining 1% of the population was served by plants with no treatment system, which primarily drew water from groundwater sources.

Water use by sector

The survey collected data on the use of potable water by sector for the first time in 2011 (Table 4). Chart 3 shows that the portion of water volumes used by the residential sector was 43% or 2,196 million cubic metres. The industrial, commercial, institutional and other non-residential uses combined used 1,092 million cubic metres (21%). Nationally, the end-use for 18% of the total water volume (930 million cubic metres) was unknown to the respondent and could not be allocated to a particular sector. Losses from the distribution system (such as leakage) made up 13% of the volume produced. The remaining 4% of water was not allocated to a specific user because it was reported as wholesale transfers to other jurisdictions.

The provinces and territories with the highest percentage of unknown water use were the Northwest Territories (67%), Newfoundland and Labrador (67%), New Brunswick (52%) and Québec (30%) (Table 4). Higher proportions of unknown water use reduce the accuracy of average daily water use estimates.

Average daily water use

In total for all sectors ⁶ , Canadians served by drinking water plants used an average of 483 litres of water per person per day in 2011 (Table 4), a reduction of 12% from 550 litres per person per day in 2007. For plants reporting the percentage of water used by the residential sector, the average person used 251 litres per day at home in 2011.

Newfoundland and Labrador, Prince Edward Island, New Brunswick, Quebec, British Columbia and Yukon were higher in total water use per capita than the national average (Chart 4 and Table 4). Total water use per capita was lowest in Manitoba, Alberta and the Northwest Territories.

In terms of residential use, households in Newfoundland and Labrador, Prince Edward Island, New Brunswick, Quebec, British Columbia and Yukon used more water per capita than the Canadian average. Residents of the three Prairie Provinces used the least.

Many factors can account for differences in water use, including water metering and pricing, water supply shortages, conservation measures, climate, demographics, dwelling types, economic activities and the state of infrastructure.

The decline in per capita water use is influenced both by increasing population and decreasing drinking water demand. Results from an Environment Canada survey showed a decline in per capita water use between 2001 and 2009 in Canada. ⁷  The trend of waning demand over the last decade mirrors that being experienced in the United States. ⁸ 

Capital expenditures

Capital expenditures on drinking water plants totalled $1,336 million in 2011 (Table 5). ⁹  Plants treating primarily surface water received most of this investment ($1,075 million or 80%). Plants treating primarily groundwater spent $205 million (15% of the total) and the remainder was spent by plants treating primarily mixed or GUDI source water. These expenses exclude costs related to the distribution of potable water.

Compared to 2007, capital expenditures in 2011 were 51% greater as the result of upgrades to existing infrastructure and new water treatment plants being commissioned. The increase was larger for plants treating primarily groundwater (+97%) or GUDI (+65%) and smaller for those treating primarily surface water (+45%) or mixed source water (+28%).

Operation and maintenance costs

In 2011, drinking water plants spent $882 million on operation and maintenance (O&M), including $338 million on labour, $213 million on materials, $200 million on energy and $130 million on other requirements for the acquisition and treatment of potable water (Tables 6-1 and 6-2). Total O&M costs rose by approximately 9% from $807 million in 2007. These expenses exclude costs related to the distribution of potable water.

On average, drinking water plants incurred about $173 in O&M expenses to supply one thousand cubic metres of potable water in 2011, or about 17 cents per cubic metre (Table 6-3). A cubic metre is equal in volume to about five household hot water tanks. Labour costs were responsible for 38% of O&M expenses, materials for 24%, energy for 23% and other types of O&M costs for 15%.

Nationally, O&M costs in 2011 were $150 per thousand cubic metres for plants treating primarily surface water (Table 6-4) and $334 per thousand cubic metres for plants treating primarily groundwater and GUDI (Table 6-5).

A number of factors influence O&M costs, such as source water type, plant size and method of treatment. ¹⁰  Costs per unit of volume are lower for surface water plants in part because they are mostly high-volume plants that benefit from economies of scale (Table 6-4). Plants that treat groundwater or GUDI supplies are mostly lower-volume plants (Table 6-5). Chart 5 demonstrates the effect of plant size (based on production volume categories) and main source water type on O&M costs per unit volume in 2011. For both source water types, costs per unit volume went down as production volumes went up.

For plants treating primarily surface water, O&M costs ranged from $85 to $809 per thousand cubic metres, whereas for plants treating mainly groundwater and GUDI, O&M costs ranged from $185 to $564 per thousand cubic metres, depending on the plant size. Only surface water plants treated more than 50,000 cubic metres per day. In the medium size categories (between 10,000 and 50,000 cubic metres per day), O&M costs per unit volume were similar for both source water types. In the three smallest plant size categories, O&M costs per unit volume for surface water exceeded those of groundwater and GUDI by considerable margins.

The O&M costs associated with treating water also varied by plant type. In 2011, O&M costs for conventional plants and direct filtration plants were $203 and $104 per thousand cubic metres of production, respectively (Table 6-3).

Overall, O&M costs associated with the acquisition and treatment of water ranged from $74 to $936 per thousand cubic metres because of differences in plant size, treatment technology and source water type.

Source water quality

Under the Canadian Environment Sustainability Indicators ¹¹  (CESI) project, fresh water quality is assessed by Environment Canada using a network of 173 core monitoring stations from federal, provincial, territorial and joint programs. This network was established to monitor water quality for the protection of aquatic life and pressures on them from human activities.

Other networks of water quality information include source water monitoring done by drinking water plant operations. Water utilities then can also play a role in assessing source water quality and ecosystem conditions. ¹²  Monitoring of source water intakes provides water quality information from over 800 surface water and over 950 groundwater sites across Canada.

Source water quality – Temperature

Water temperature affects many other water quality parameters; for example, the concentration of pathogens in water can rise as temperature increases. ¹³  Chart 6 contrasts the seasonal variation of water temperature in raw groundwater and raw surface water sources in 2011.

The monthly maximum temperature for raw groundwater sources was relatively stable, with median maximum values ranging between about 9°C and 10°C. Monthly maximum temperatures of raw surface water sources, which are more influenced by seasonal weather fluctuations, had median values that ranged from 3°C to 22°C, peaking in August.

Source water quality – Total coliforms

Coliforms are a group of bacteria that are naturally found on plants and in soils, in water, and in the intestines of humans and warm-blooded animals. Because they are widespread in the environment, they are not good indicators of faecal contamination in surface water and GUDI sources. Conversely, total coliforms can be used to indicate potential contamination of groundwater, since coliforms should not be found in these sources. ¹⁵ 

The monthly data from two quantitative test methods (see text box above) are pooled together in Chart 7 to show the distribution of monthly maximum total coliform values for 2011 in raw surface water and raw groundwater sources (no GUDI sources are included). Ninety-seven percent of total coliform maximums in groundwater were less than 10 CFU or MPN per 100 mL, compared to 22% for surface water. Results from 2005 to 2007, which only reported CFU ranges, were similar at 94% and 21% respectively. ¹⁶ 

Source water quality – Escherichia coli (E. coli)

E. coli is naturally found in the intestines of humans and warm-blooded animals but usually does not occur naturally on plants or in soil and water. E. coli is well recognized as an indicator of recent faecal contamination and can indicate an increased potential for pathogens to be present in both surface and ground water sources. ¹⁷ 

The monthly data from two quantitative test methods (see text box above) are pooled together in Chart 8 to show the distribution of monthly maximum E. coli values for 2011 in raw surface and raw groundwater sources (no GUDI sources are included). The presence of E. coli was lower in groundwater sources, as 89% of the monthly maximums were zero compared to 22% for surface water sources. For groundwater, 99.7% of E. coli maximums were less than 10 CFU or MPN per 100 mL, compared to 64% of surface water maximums. Results from 2005 to 2007, which only reported CFU ranges, were similar at 99% and 64% respectively. ¹⁸ 

Elimination of coliforms and E. coli is the objective of the primary disinfection processes applied at treatment plants. Secondary disinfection processes are also applied to maintain a disinfectant “residual” throughout the distribution system to avoid recontamination before water reaches the final user. Chlorination, which can be used for both primary and secondary disinfection, was applied to 96% of the water processed by drinking water plants in 2011 (Table 3-2). Ultraviolet irradiation and ozonation, which are effective for primary disinfection only, were applied to 21% and 27% of treated water respectively.

Source water quality – Surface water turbidity

Map 1 presents the median values of monthly maximum turbidity for raw surface water sources by drainage region from plants that reported data for at least 10 months of the year. The results, which represent 90% of the surface water processed by drinking water plants, show that turbidity levels were lowest on the east and west coasts and highest in the interior. Surface water sources in the Assiniboine–Red (12), the North Saskatchewan (10), Lower Saskatchewan–Nelson (14) and the St. Lawrence (21) drainage regions had the highest median maximum turbidity, in the range of 7.0 to 11.4 NTU in 2011.

Source water quality – Surface water pH and alkalinity

The pH of source water is an important parameter for drinking water plants to monitor because specific pH ranges are required for a number of treatment processes as well as for corrosion control in the water distribution system. In 2011, pH adjustments for process control were made for just over 30% of all surface water processed by drinking water plants (Table 3-2). Table 7-1 shows the median values of annual minimum, average and maximum pH levels reported for raw surface water by drainage region in 2011. The data, which represent 88% of the surface water processed by drinking water plants, show that source water pH ranges tended to be lower on the east coast — the Maritime Coastal (24) and Newfoundland–Labrador (25) drainage regions — compared to elsewhere in Canada.

Alkalinity ²²  is a measure of the capacity of water to neutralize acid. Geology can influence water quality. For example, areas that have primarily granitic rocks will be lower in alkalinity and those with more limestone will have higher alkalinity. ²³  Alkalinity is adjusted to optimize treatment processes and provide a stable pH in the distribution system. In 2011, alkalinity adjustments for process control were made for nearly 10% of all surface water processed by drinking water plants (Table 3-2). Table 7-2 shows the annual median minimum, average and maximum total alkalinity values reported for raw surface water by drainage region. The data, which represent 86% of the surface water processed by drinking water plants, indicate that source water alkalinity was generally higher in the interior of Canada than it was on the coasts, with the exception of the Winnipeg drainage region (13).

Source water quality – Surface water colour

The presence of natural organic matter in surface water, particularly aquatic humic matter, can cause a yellow-brown colour. ²⁴  The presence of metals such as iron, manganese and copper can further intensify water colour. Changes in water colouration may also be used as an indicator of environmental impact from human activities in certain situations. ²⁵ 

Table 7-3 shows the annual median minimum, average and maximum colour values reported for raw surface water by drainage region for 2011. The data, which represent 68% of the surface water processed by drinking water plants, show that surface water in the drainage regions within British Columbia — Fraser–Lower Mainland (2), Okanagan–Similkameen (3) and Columbia (4) — had less colour in contrast to other regions in Canada.

Source water quality – Groundwater

Groundwater quality monitoring is also an important part of source water protection programs. Over 950 groundwater sources in Canada were included in the Survey of Drinking Water Plants. However, data on source water quality was only received from plants representing less than 50% of the groundwater production volume. Given the lower response rates, developing national estimates of source water quality parameters for groundwater are not included in this report.