Saint-Bruno-de-Montarville, Que., has lifted its boil-water advisory Monday, but it remains in place for Boucherville.
The advisory has been in place since Friday, when E. coli bacteria was found in the water supply.
Some residents have said they weren't informed of the advisory.
Matthew Banks, a father of three in Saint-Bruno de Montarville, learned of the measure on Sunday after it had been in place for two days.
"I don't even know where to go from here,'' he said in an interview with The Canadian Press on Monday. "We've been drinking the water, using it to wash dishes and stuff, and everyone seems to be fine."
But, he added, he's bothered that he learned about the boil water advisory via a local Facebook group.
"We have electric signs," he said, "We're not in the 19th century. With today's technology, there's no reason why we can't advise the community of this."
He noted Meta, Facebook's parent company, is blocking Canadians from viewing links to news after the Online News Act required tech giants to pay for the news content shared on their platforms.
"That's where a lot of people get their news from," Banks said. "But there's no reason why [the city] can't do a massive telephone call, or an advisory on electronic signs, or something."
In an email, Saint-Bruno de Montarville said it's keeping people updated through its official Facebook page.
Lavigne said Boucherville is sending messages directly to around 20,000 residents — roughly half the city's population — who have signed up to receive texts, calls or emails from the city.
It's also communicating through its website and Facebook page, she said, adding people are being encouraged to share information with those around them.
The city of Longueuil said Sunday it had experienced an issue with its emergency alert system the day the advisory took effect and was investigating the cause.
In an emailed statement, Longueuil said it's still investigating the source of the contamination, adding that only a single sample tested positive for E. coli.
The city of Longueuil lifted its boil-water advisory for the boroughs of Vieux-Longueuil and Saint-Hubert Sunday.
"The results of recent analyses carried out on the Longueuil water network are in order. Longueuil residents affected by the advisory no longer need to boil their water before drinking it," the city said in a news release.
The city said it is still waiting for the results of an analysis of samples from the water plants serving Boucherville. Water should still be heated to a rolling boil for a full minute in order to be safe to drink, wash food, give to pets or brush teeth.
For more information, visit the city of Longueuil's website and the section dedicated to drinking water or call 311.