The City of Toronto’s targeted testing of tap water in 2017 indicated significantly lower lead levels, a result of a Corrosion Control Plan implemented from 2009 to 2017.

The Safe Drinking Water Act requires that fewer than 10 per cent of water samples can exceed 10 parts per billion (ppb) lead in order to be in compliance with the act. From June to October 2008, Toronto found 52 per cent of samples exceeded 10 ppb. In the same period for 2009, 18 per cent of samples exceeded the limit.

“The implementation of corrosion control at Toronto’s four water treatment plants has been completed and we are cautiously optimistic that we will continue to see a reduction in lead levels,” said William Fernandes, director of Water Treatment and Supply at Toronto Water.

The 2017 tap water test results show significantly lower lead levels compared with previous years. Of the 55 homes and businesses tested, 2 per cent of samples exceeded 10 ppb and no samples in the water distribution system exceeded 10 ppb.

“Toronto Public Health worked closely with Toronto Water on the implementation of this initiative. We are pleased with the results that show a decrease in lead in water from homes with pipes and other plumbing materials containing lead,” said Dr. Eileen de Villa, Toronto’s Medical Officer of Health.

Since Toronto City has fully implemented corrosion control, it resumed the regulated lead testing of properties known or suspected of having lead pipes as required by the Ontario Ministry of Environment and Climate Change.

The city began implementing corrosion control in 2014, which involves adding phosphate to the drinking water system at the water treatment plants. The phosphate helps form a protective coating on pipes and household plumbing fixtures, which helps to reduce the potential for lead to enter tap water. It costs approximately $3 million annually to add phosphate to the drinking water system and remove excess phosphate from treated wastewater before it is released into the lake.

Corrosion control is just one strategy the city is using to reduce lead. It is also replacing lead water services on the public side through scheduled capital projects, emergency work, and the Priority Lead Service Replacement Program. More information is available at


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