great lakes from space
Almost 60% of Ontarians get their drinking water from the Great Lakes. Changing weather patterns, low water levels, drought and flooding may threaten the quantity and quality of these water sources. Source: NASA, via Flickr.

Ontario’s drinking water is among the safest and best protected in the world, according to the province’s Chief Drinking Water Inspector’s 2015-2016 Annual Report.

Released on November 28, 2016, the report highlighted results for Ontario’s municipal drinking water systems, including:

  • 99.8% of tests from municipal residential drinking water systems met Ontario’s drinking water standards.
  • 74% of all municipal residential drinking water systems achieved a 100% inspection rating – a 7% increase since 2014-2015.
  • 99.6% of drinking water tests from systems serving designated facilities such as daycares, schools or health care centres met Ontario’s drinking water quality standards.

The report looked at a number of issues, programs and water systems, including increasing risk of algal blooms, lead in drinking water plumbing, and small drinking water systems.

Algal Blooms

Algal blooms, which are linked to climate change, can produce microcystin-LR, a toxin harmful to humans and pets. The report says operational changes implemented by Ontario municipalities have been successful is keeping microcystin-LR out of treated water.


The report shows that the majority of lead in plumbing test results meet the provincial standard with the percentage increasing each year. In 2015-2016, 95.59% of test results met standards, up from 92.69% in 2013-2014.

Twenty municipalities are required to prepare strategies addressing lead issues, a number unchanged since 2010-2011.

Lead control strategies include setting up corrosion control plans and replacing lead service lines. Six of the 20 municipalities have implemented lead control strategies, and the remaining 14 continue to make significant progress in addressing their lead issuess.

Small Systems

There are approximately 10,000 small drinking water systems in Ontario, serving thousands of businesses and community sites.

As of March 31, 2016, 16,804 risk assessments have been completed for these small systems. According to the report, over 87% were categorized as low/moderate risk and subject to regular re-inspection every four years. The remaining systems, categorized as high, risk are re-inspected every two years.

Compared to the previous year, there were 8.78% fewer adverse test results and 15.97% fewer adverse water quality incidents.

Click here to read the full report.


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