Drinking water comes from surface water or groundwater. Surface water includes lakes, rivers, streams and ponds. Groundwater is water found in soil or cracks in underground rock, then pumped out of the ground by wells. About 26 percent of Canadians and 34 percent of Americans get water from groundwater sources.
Surface water usually has a higher risk of being polluted or contaminated since it is open to the environment. Groundwater is usually safer because it is protected from most sources of pollution. However, as problems at Walkerton showed, groundwater can still be contaminated. Dugout water is not meant for drinking. It should not be used as drinking water without proper treatment.
As communities expand, the threat to drinking water also increases. Growing towns and recreation activities are intruding on pure water sources. Byproducts of our modern lifestyle, including waste from cities, agriculture and industry, are entering the water supply. Examples of pollution include surface run-off from agriculture areas, waste products from sewage lagoons or septic tanks, and oil from boats and cars.
Contamination can be in physical, microbiological, inorganic and organic forms.
Physical contamination of water includes cloudiness, or turbidity. Cloudiness is usually caused by clay and silt, sometimes a result of soil run-off and erosion.
Microbiological contamination includes the presence of bacteria, viruses and parasites. Examples are Giardia (beaver fever) and Cryptosporidium, the bug that affected people in North Battleford. In some cases, however, it is not the presence of these bugs that is a concern. Rather, the chemicals they may produce can cause problems. For instance, blue-green algae is found in many lakes in North America, especially during hot dry summers. This algae can make a toxic chemical.
Inorganic pollution includes metals such as lead and arsenic, and salts such as nitrate. Organic pollution includes pesticides.
Water suppliers use a variety of treatments to remove contamination. This may include thickening (coagulation), settling of silts and particles (sedimentation), and filtration. Disinfection follows, usually done by adding chemicals like chlorine to water. Many water treatment plants are also considering the use of ultraviolet light. It is more effective against parasites such as Cryptosporidium.
Regardless of the size of the operation, the minimum recommended treatment method for any surface water source is filtration and disinfection. The minimum method of treatment for groundwater is disinfection.
In a typical community water supply system, water is pumped from surface or groundwater into a provincially-approved water treatment plant. Treated water is then transported under pressure through a network of buried pipes, reservoirs and main water lines to bring water to our houses. In many places, pumping water up into a storage tank provides water pressure. The tank stores the water at a higher elevation than the house. The force of gravity then pushes the water into the home when the tap is opened.
Houses on a private supply usually get water by drilling a well to reach groundwater sometimes hundred of metres below the surface. A pump then brings the water up into a storage tank inside the home to be stored under pressure. In Alberta about 600,000 people, or 20 per cent of the population, get water from wells or private systems. These are not licensed by the provincial environment department. Many people in rural areas have contracts with water hauling companies to truck water from cities or towns to store in cisterns.
In Canada, the federal government sets safety limits for substances and conditions known to affect drinking water quality. The information is published in Health Canada's Guidelines for Canadian Drinking Water Quality. Provincial governments may choose to use these guideline limits. They may also adopt appropriate recommendations from the United States Environmental Protection Agency (USEPA).
Provincial environment departments license all municipal water treatment plants. Their license agreements give the plant conditions for processing water. All violations must be reported. The provincial environment department works with water treatment plants to constantly improve the system and staff training. All water treatment plants must submit regular water samples for testing. In Alberta, all water sample results are sent directly to Regional Health Authorities (RHAs). Under this system health officials must be told of any unacceptable results, even during weekends and holidays. RHAs must make sure the water is safe to drink. If the RHA finds a problem in the drinking water, the Medical Health Officer will issue a Boil Water Advisory. Information will also be released to the public about the safety of the water.
Provincial environment departments and RHAs work closely with water treatment plant operators to make sure water is safe.
Owners of private homes are encouraged to regularly submit water samples for testing. Information on collecting water samples can usually be obtained from the local health department.
In Canada, other government agencies also provide information on safe drinking water, especially in rural areas. These include the federal Department of Agriculture and Agri-Food Canada Prairie Farm Rehabilitation Administration and provincial agriculture departments.
You can help by keeping bodies of surface water unpolluted. Avoid dumping waste from your boat, cottage, recreation vehicle and septic tank. Waste dumped into a river or lake may be carried away by the current, but will never disappear. It re-emerges downstream, sometimes changed, often just diluted.
Fresh water bodies have a great ability to break down some waste materials, but not in the amounts generated today. This overload of nature's ability to clean up is called pollution. A septic tank that is not maintained or installed properly can also pollute the groundwater system.
In the city, be careful with hazardous products including waste oil, pesticides, solvents or paints. Do not dump them onto driveways, road ditches or storm drains. Storm drains may flow directly into lakes or rivers. As well, do not misuse the sewage system. Pouring toxic household products down the toilet damages the environment and may return harmful substances through the water cycle.
Use fewer pesticides and hazardous products in the garden and the home. Use more environmentally friendly products by looking for the Environmental Choice Program EcoLogo. Products with this label have been tested and certified by the Canadian Standards Association, and may create less pollution.
It is also important to save water. Ask your local utility service about water conservation methods. Get involved with your community's home hazardous waste disposal program by getting rid of toxic products properly at approved locations. Keeping our water sources in mind will help make sure water remains safe for our children to use.