How many Canadians get sick each year from microorganisms in their drinking water? What caused recent outbreaks of waterborne illness? What should you do if your water supply goes bad?

Take our quiz about waterborne disease in the news and find out how much you really know about what lurks in Canada's drinking water!

In November 2006, a boil-water advisory was issued for greater Vancouver because the water contained:

E. coli bacteria
Raw sewage
Cryptosporidium protozoa
None of the above

None of the above

The boil-water advisory was issued as a precaution, after torrential rains washed dirt and debris into the reservoirs that supply Vancouver's drinking water. The water had become turbid (cloudy with floating particles), and turbidity can make water-disinfecting procedures less effective. At the same time, the heavy rains had increased the risk of contamination, because rapid run-off can wash animal faeces and other unsavoury objects into reservoirs.

In 2005, about 800 residents of an Ontario community were evacuated because of ongoing problems with the water supply in their area. Where did this happen?



Almost half the residents of this community in northern Ontario were moved to other locations in November of 2005. The residents of Kashechewan had been living under a boil-water order for two years, and tests detected E. coli in their drinking water. Many of the residents also were suffering from rashes and skin diseases that may have been caused or aggravated by poor water quality.

Health Canada advocates a "multi-barrier" approach in order to ensure that your drinking water is safe. "Multi-barrier" means that:

Water quality is defended at source, treatment plant, and in the distribution system
All water must pass through 3 different types of filter before being distributed
Areas where drinking water is collected and treated must be secured behind fences
All drinking water flows over a series of baffles to purify and aerate it before distribution

Water quality is defended at source, treatment plant, and in the distribution system

The "multi-barrier" approach looks at possible threats to water quality all along the supply route and then tries to prevent these potential problems. The strategies include selecting the best available source of water, protecting it from contamination, using effective water treatment, and preventing water-quality deterioration in the distribution system.

This approach recognizes that while each individual barrier may be not be able to completely remove or prevent contamination, and therefore protect public health, together the barriers provide greater assurance that the water will be safe to drink over the long term.

On April 25, 2001, a boil-water advisory was issued for North Battleford, Saskatechewan, after 10 cases of an illness usually transmitted through water were reported. What was the illness?



Cryptosporidiosis is caused by a common one-celled parasite called Cryptosporidium that infects humans and many animals. The microorganism that causes the illness is found in almost every lake and river in Canada, but is usually removed by filters at water-treatment facilities.

North Battleford draws part of its drinking water from the North Saskatchewan River. Cryptosporidia entered the water supply after a filtration unit did not resume proper functioning when restarted after maintenance.

Health Canada estimates that 6,000 to 8,000 people among a population of 14,000 fell ill during this outbreak. Fortunately, there were no deaths.

According to Statistics Canada, how many Canadians are killed each year by microorganisms in their drinking water?



Drinking water contaminated by microorganisms causes an estimated 90 deaths a year in Canada. It also causes about 90,000 cases of illness.

Usually, we hear only about outbreaks that affect large numbers of people. Many incidents are small and isolated: one farm's well becomes contaminated, for example, or a hiker falls ill after drinking untreated water from a stream.

In 1995, a single-celled parasite that causes the disease toxoplasmosis was detected in the drinking water of Victoria, B.C. People usually catch this disease through raw or undercooked meat or from house cat faeces. How did the parasite get into Victoria's water?

From cougar droppings near a reservoir
From a dead cow buried near a municipal well
Flushable kitty litter contaminated water near an intake pipe
Someone threw a dead pig in a reservoir "as a joke"

From cougar (mountain lion) droppings near a reservoir

Victoria draws its drinking water from a reservoir in the hills outside the city. The area is wilderness, and cougars regularly frequent the area around the reservoir. Researchers also found some domestic cats that had "gone wild" living in the vicinity. Rain washed the Toxoplasma gondii cysts from the cougar and cat feces into the reservoir.

The cysts are resistant to chlorine, and so were not killed by the usual municipal water- treatment procedures.

Boil-water orders are issued:

When there is evidence of dangerous levels of microorganisms in water
When water becomes turbid (filled with particles)
As a precautionary measure when there is a concern that contamination may occur
All of the above

All of the above

Many boil-water orders are issued as a precaution, rather than after there is firm evidence of contamination. Orders may be issued when a water pipe has broken or been disturbed by construction, because there is a chance that microorganisms may have entered the water "downstream" from the treatment plant through the break or disconnection. Orders are also issued as a precaution when water becomes turbid (cloudy), since turbidity can reduce the effectiveness of the usual disinfecting procedures.

In April 2004, a boil-water advisory affecting over 40,000 people was issued in Saint John, New Brunswick. It was necessary because:

Giardia had been detected in the water system
A chlorine pump at the water-treatment plant had broken down
Heavy rains had washed silt and debris into the water supply
All of the above

A chlorine pump at the water-treatment plant had broken down

Residents of the east end of Saint John had to boil water for five days after a chlorine pump malfunctioned. The backup pump and alarm also failed to operate, so municipal water had been pumped out to a large part of the city without adequate treatment.

In the summer of 1996, two cities in the same province suffered major outbreaks of illness caused by Cryptosporidia in the water supply. Which province?

British Columbia

British Columbia

The first outbreak, which affected about 2000 people, was in the community of Cranbrook. A few weeks later, Kelowna suffered an outbreak in which an estimated 10,000 to 15,000 became ill.

British Columbia suffers the highest rate of "Crypto" outbreaks in Canada because many of its communities draw their water from open reservoirs, lakes, or rivers, almost all of which contain some naturally occurring Cryptosporidium. In provinces where more communities draw their water from underground sources, the rate of outbreaks is lower.

"Most Canadians take it for granted their drinking water is safe, but the nearly half million Canadians living in _____ have no such assurance."
Johanne Gélinas, the Commissioner of the Environment and Sustainable Development, 2005

Where do these Canadians live?

In Newfoundland and Labrador
In the North
In rural areas
In First Nations communities

In First Nations communities

This quotation describes the results of an audit of water quality conducted in 2005 under the auspices of the Auditor General. It found that:

In 2001, Indian and Northern Affairs Canada found a significant risk to the quality or safety of drinking water in three quarters of the water systems in First Nations communities.[In 2005] many First Nations communities remain exposed to risks from unsafe drinking water. Aside from the lack of laws and regulations on drinking water in First Nations communities, the technical support available to First Nations, such as training in operations and maintenance, is also inadequate.

At the time of the report, one First Nation in B.C. had been under a boil-water order for nine years!

In November of 2006, a boil-water advisory was issued for Greater Vancouver. The advisory made headlines across Canada because:

It became the longest-running advisory in Canadian history
It affected more people than any previous boil-water order in Canada
It was made in response to a suspected terrorist attack on the city's water supply
Authorities were criticized severely for not acting sooner

It affected more people than any previous boil-water order in Canada

The Vancouver advisory affected about one million people, including residents, commuters, and visitors. The logistical challenge was huge: getting word out to a million people, explaining what measures to take, and getting safe water to vulnerable populations, such as the homeless.

The advisory was issued as a precaution after torrential rains washed mud and debris into the mountain reservoirs that supply the city's water. It lasted for 12 days, until the turbidity (cloudiness) of the water subsided.

If a boil-water order is issued for your area, you need to disinfect:

Water that looks cloudy
Your drinking water supply
All water that may ultimately enter anyone's mouth
All water entering your home

All water that may ultimately enter anyone's mouth

This includes water for drinking, making beverages, making ice cubes, washing fruit and vegetables, adding to food, mixing infant formula and foods, and brushing teeth.

Water for such purposes as laundry, showers, household cleaning, and toilet flushing does not have to be disinfected.

In May of 2001, one province had 322 boil-water advisories in place, affecting more than 83,000 people. Which province was this?

Newfoundland and Labrador
British Columbia

Newfoundland and Labrador

Most of these advisories were not due to disease outbreaks, but were put in place as a precaution because drinking water was inadequately chlorinated - or not chlorinated at all. At the time, nearly 90 smaller communities across the province lacked water disinfecting facilities.

Which city had an outbreak of Giardiasis ("beaver fever") spread through its municipal water supply?

Banff, Alberta
Edmonton, Alberta
Dauphin, Manitoba
All of the above

All of the above

Banff had an outbreak in 1981-2, Edmonton in 1982-3, and Dauphin in 1995. Giardiasis outbreaks have occurred in many other communities, including Penticton, Princeton, and Creston in British Columbia, Temagami in Ontario, and the Shoal Lake First Nation in Manitoba.

This water-borne disease was common in Canada until the 1950s, but has now almost totally disappeared:

None of the above


Poliomyelitis was once a much-feared disease in Canada. Although it could be caught at any age, it most frequently struck children under the age of three. It could be fatal and could also cause life-long paralysis. Survivors sometimes could not breathe on their own and were confined to "iron lungs" to keep them alive.

In 1952, an effective vaccine against polio was developed. Public health officials began a mass vaccination campaign in the mid-1950s, and the last major polio outbreak in Canada occurred in 1959. Today, polio is rare in Canada; the few cases usually have been contracted elsewhere and brought into Canada by returning travellers or immigrants.

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