Epcor is assuring Edmontonians their tap water is safe after an investigation revealed some residents have been drinking water that far exceeds federal safety guidelines for lead contamination.

"Nothing has changed overnight with Edmonton drinking water – it continues to be safe to drink," Edmonton's water utility company said Monday on Twitter.

"Lead in drinking water at the levels we have found in Edmonton is not an acute or immediate health risk."

The comments follow the release of data obtained by a consortium of media organizations on the presence of the poisonous metal in drinking water across Canada.

The year-long investigation by more than 120 journalists from nine universities and 10 media organizations, including The Associated Press and the Institute for Investigative Journalism at Concordia University, tested exposure to lead in 11 cities including Edmonton.

New guidelines

Test data obtained from Epcor reveals lead levels in some Edmonton houses has exceeded the current federal safety guideline of five parts per billion (ppb) every year since 2008, with the highest readings exceeding 400 parts per billion.

In March, Health Canada cut the guideline for acceptable lead levels in drinking water in half — to five ppb from 10 ppb. This change has also moved the point of compliance from the water main to the tap.

At the time, Health Canada warned of lead's adverse health effects including reduced cognition, increased blood pressure and renal dysfunction in adults, and the risk of reduced IQ in children who are especially vulnerable to exposure.

On Twitter, Epcor said its new lead mitigation strategy, approved by city council earlier this year, will deal with the most common source of lead contamination in the city — old service lines.

"The bottom line: Edmonton's drinking water is safe, and Epcor's lead mitigation strategy will make Edmonton among the first communities in Canada to meet Health Canada's new national drinking water standards," Epcor said.

"When drinking water is treated and distributed, it contains no measurable level of lead. The most common sources of lead in drinking water are lead service lines."

The bottom line: Edmonton’s drinking water is safe, and EPCOR’s lead mitigation strategy will make Edmonton among the first communities in Canada to meet Health Canada’s new national drinking water standards. Visit <a href="https://t.co/8HWpswpugM">https://t.co/8HWpswpugM</a> to learn more. <a href="https://twitter.com/hashtag/yeg?src=hash&ref_src=twsrc%5Etfw">#yeg</a> 9/9 —@EPCOR

Epcor has replaced all lead water mains in Edmonton. However, each home has a service line that runs from the water main under the street to the house.

About 4,450 homes in Edmonton have lead service lines on either side of the property line, the company said.

These are homes that were typically built before 1960 — when lead was still widely used in plumbing — and represent about 1.6 per cent of the 270,000 homes in the city supplied by Epcor, the company said. Currently, residents must pay to replace lead service lines on their property.

But under the new strategy, Epcor will soon pay to replace the private portion of lead lines any time it replaces the utility portion. The company will also prioritize the replacement of pipes in homes that continue to exceed safety guidelines.

"We've been testing and we've been reaching out to the homeowners and tenants in those homes for about 10 years now," said Steve Craik, Epcor's director of quality assurance and environment.

"They've all been informed. We do a mail-out once a year, sometimes more than once a year, to the residents in those homes," Craik said in an interview Tuesday with CBC Radio's Edmonton AM.

"We've been offering filters as well and we've been reporting the lead results directly to the people in those homes."

However, contamination was not only found in homes with lead service lines. Data from Epcor testing conducted from 2008 to 2018 shows the metal is present in homes even without the old pipes.

About 27 per cent of 5,390 samples collected from lead service pipes during the 10-year period were unsafe. Of 533 samples collected from non-lead service lines, more than five per cent were considered unsafe.

Additional testing by Epcor in April 2019 revealed that about 8.5 per cent of randomly conducted samples from homes across the city are "likely to have lead levels that will exceed a new, lower Health Canada guidelines for drinking water quality," Epcor said in a report on its lead mitigation strategy.

The source of lead in the homes is likely old internal plumbing components and fixtures, Craik said.

"It's an issue," he said. "It's not as serious of an issue as the lead service lines but we are aware of it and that is one of the reasons that we're going forward with the orthophosphate because that will be effective against that old plumbing as well."

Epcor will soon begin adding orthophosphate to the drinking supply. The corrosion inhibitor is expected to reduce lead concentration at the tap, not only in homes with lead service pipes but also in homes with other sources of lead, such as solder and brass.

The testing of orthophosphate began in early 2017. The company is working to determine the appropriate dosing level for Edmonton's water chemistry. The new treatment system should be brought online by late 2020, Craik said.

The new guideline is a "difficult" one but the company is committed to meeting it, Craik said.

"We've been through the testing on that and we've started to build the systems.

"And for those homes who might still test above the guideline even after we've done that, we're going to be paying for the replacement of the whole lead service line."