MONTREAL — Water contamination has led to 1.3 million of the 1.8 million residents in Montreal, Can. to be issued a boil-water advisory, according to the Montreal Gazette.

One of the island’s largest water filtration plants spurred the largest advisory in the city’s history after a problem occurred during routine maintenance, noted the article.

The advisory was issued at 9:30 a.m. on the morning of May 22, 2013 and was to last for at least 24 hours.

Officials with the city’s water department said the advisory was a precautionary measure and noted that the contamination was likely limited to non-toxic sediment, stated the article.

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During regular maintenance at the Atwater filtration plant water levels fell far lower than they were supposed to, causing officials to send out an emergency notice to residents through its 911 message service.

“For a reason we’re not aware of yet, the water went down at least 30 feet (10 meters),” said Chantal Morissette, head of Montreal’s water supply department. “It was almost emptied. This stirred up particles that were deposited at the bottom of the reservoir.”

Read the entire article here.