The Ottawa-Carleton District School Board has a problem with dangerous levels of lead in drinking water at some of its schools, according to a new report from the Canadian Environmental Law Association (CELA).
More than 100 samples of drinking water from OCDSB school taps exceeded the provincial lead maximum in 2024/25, according to the report.
And, using Health Canada’s even more stringent guideline for lead in drinking water, the number of tests in which lead exceeded acceptable levels at the Ottawa board topped 150.
Several tests also showed high lead levels at some other Ontario school boards, including the Dufferin Peel Catholic District School Board; Peel District School Board; Toronto District School Board; and the Ottawa Catholic School Board.
Within the OCDSB, the report cites Orleans Wood Elementary School, Fallingbrook Community Elementary School and Manor Park Public School as having the worst test results last year.
Thousands of drinking water samples that exceed provincial standards in schools and daycares across Ontario — and sometimes even the safety measures in place to address them — are exposing students to drinking water “that would be considered unsafe in the majority of the country,” says the report.
No amount of lead in water is safe for children, according to the World Health Organization. Even low levels are linked to decreased IQ and attention span, motor skill weakness and behavioural problems.
“Minor increases in exposure, even one microgram per decilitre, can reduce a child’s IQ on average by about one to one and a half points and put children at greater risk for ADHD-type behaviours,” said Bruce Lanphear, an early childhood health and lead-poisoning expert at Simon Fraser University.
Ontario, unlike almost all other provinces, has maintained what some experts call an outdated safety guideline of 10 parts per billion (ppb) — double Health Canada’s federal guideline of five ppb.
Many schools narrowly remain within the provincial guideline but still exceed what the federal government considers safe.
“Because lead is such a pernicious and clearly understood neurotoxin, what you really want to do is minimize lead exposure,” said Miriam Diamond, an environmental sciences expert and professor at the University of Toronto. “Studies continue to push down the level of safe lead exposure.”
Flushing taps doesn’t fix things: report
The primary fix for high lead levels in schools and daycares under Ontario legislation is to flush the taps once daily — a solution that fails to reliably address the risks, says the CELA report.
Flushing is not a solution, said Simon Fraser’s Lanphear. “Maybe for a day or two with lower lead levels, but people won’t do it. You can’t sit at a fountain for 30 seconds or two minutes every time you get a drink. Maintenance workers won’t do it. It’s completely flawed.”
Cambridge Street Community Public School is an example of a school in the Ottawa board that struggled with elevated lead levels for years despite flushing the taps.
In September 2020, a newly installed water bottle filling station at the school contained 136 ppb of lead in one water sample — more than 13 times the Ontario safety guideline for lead in drinking water.
That test result is one of at least 33 that exceeded Ontario safe levels between 2020 and 2025 at the school, which has about 100 students from kindergarten to Grade 6, according to data provided by CELA.
For two years after discovering elevated lead, the school’s flushing protocol did not prevent lead levels at the filling station from spiking back above safe thresholds for drinking, the CELA report says.
It took multiple rounds of testing before lead levels consistently fell below the threshold.
Just over a week after the fixture’s second advisory in August 2022, Ottawa Public Health reinstated the water bottle filling station, following two consecutive flushed sample results below 10 ppb. According to water testing data provided under the Freedom of Information Act, the fixture has had no further testing since the 2022 lead spikes, CELA says.
An OCDBS spokesperson said that, since 2017, the board has “regularly tested designated drinking water locations in all OCDSB schools. Any fixture exceeding provincial lead standards is immediately taken out of service and remediated.
“We follow all provincial regulations to ensure these locations are safe before re-opening them for consumption,” said Diane Pernari, general manager of communications and public relations. Testing results are posted on the board’s website.
The CELA report identifies Ontario’s heavy reliance on flushing taps as a major safety concern, saying “research shows that lead concentration in water can return to dangerous levels just minutes or hours (after flushing a fixture).”
“Ontario hasn’t recognized that no amount of lead is safe,” says Julie Mutis, lead author of the CELA report.
A provincial spokesperson said schools, private schools, and childcare centres are “required to flush their plumbing on a daily or weekly basis, depending on the most recent fixture test results.
“Where lead levels exceed the provincial drinking water quality standard of 10 micrograms per litre (10 µg/L), facility owners … must take immediate corrective action as directed by the local medical officer of health,” said Lindsay Davidson of the Ontario Ministry of the Environment and Climate Change.
“This approach has ensured there have been no reported cases of lead poisoning in children due to drinking water in the last 10 years.”
Internal documents obtained by the IJB last year show that Ontario officials have discussed toughening the province’s lead standards to match Health Canada’s five-ppb guideline since at least 2021.
Quebec was the first province to mirror Health Canada’s tougher guideline on lead in drinking water.
Quebec’s stricter approach to tackling lead is also backed by more transparent reporting, and since 2021, the province has replaced or added filters to 61 per cent of fixtures that tested high for lead. Parents and staff can view biannual, accessibly formatted reports that list how many school taps and fountains are compliant.
In 2024, the IJB launched a database in collaboration with the University of Toronto’s HIVE Lab, where parents can check lead test results for Ontario schools and daycares between 2019 and 2023.
This story was also published in the Ottawa Citizen