Groundwater in Canada
Overview
Groundwater refers to water reservoirs stored in deep geologic formations known as aquifers. Groundwater sources vary in their capacity, depth and quality. Nonetheless, they are an important source of freshwater. It is estimated that if all groundwater on Earth were to submerge the planet it would completely cover its surface to a depth of 120 meters! In contrast, all surface water on Earth from lakes, rivers and swamps can cover the entire planet surface with only 0.25 meter.
In Canada, 8.9 million people rely on groundwater for domestic use. This represents about 30% of total freshwater sources consumed by Canadians. Certain regions in the country depend more on groundwater than others. For instance, Prince Edward Island relies 100% on groundwater since they do not have significant sources of surface water. Similarly, New Brunswick obtains 60% of its freshwater from groundwater sources.
Groundwater is normally accessed by means of a well. A pump is typically installed to pump water for consumption. In rural Canada and Prairie Provinces, groundwater is relied upon for crop irrigation. In British Columbia and Quebec, on the other hand, groundwater is used mostly for industrial applications.
Groundwater as a Source of Energy
Some groundwater reservoirs contain hot water. This heat can be harnessed to provide domestic heating. While the technology is not yet widespread, there are successful examples of smart utilization of groundwater as an energy source. For instance, the City of Moose Jaw in Saskatchewan uses a geothermal heating system to heat a public swimming pool. Similarly, Carleton University in Ottawa uses hot groundwater to heat its buildings.
Groundwater Quality
Mother Nature has provided a natural filtration system for groundwater, and humans have been depended on it for thousands of years. The various layers of silt, sand and rock that cover aquifers act as natural filters that remove sediments and impurities, particularly harmful microorganisms. Unlike surface water, groundwater is generally confined and not exposed to the multitude of contamination sources, and that preserves its pristine quality.
However, groundwater is susceptible to contamination from nearby pollution sources. For example, leaking gasoline tanks from gas stations, leaking septic tanks in cottages or wastewater leachate from landfills can seriously contaminate groundwater with serious diseases.
The unfortunate Walkerton tragedy for instance occurred due to contamination of well water by manure that leached into the soil from a nearby farm (combined with improper treatment). In Ville Mercier, Quebec, a similar incident happened where industrial waste contaminated local groundwater supplies, and residents had to pump water from a well 10 kilometers away from their community to provide an alternative source of safe water.
In general, groundwater has larger values of hardness and dissolved minerals than surface water, yet this is not always the case. Unlike surface water, groundwater preserves its quality, temperature and other parameters over time and is less susceptible to weather fluctuations and land use.
When designing a water treatment system for a well, it is advisable to perform detailed water analysis to ensure that water is microbiologically safe for consumption. Depending on water quality and local regulations, additional treatment or disinfection may be necessary.