A boil-water advisory affecting large sections of the south shore will remain in effect until at least noon Friday, according to a city spokesperson.

Jacques Tetrault tells CJAD they have to be sure the water is completely free of bacteria before they can lift it.

This follows a massive water main break on Roland-Therrien Blvd. in Longueuil Wednesday morning. The advisory touches residents of Old Longueuil and St-Hubert, as well as Boucherville, St-bruno de Montarville and Carignan-sur-le-Golf.

It affects about 190,000 residents.

Those residents are being advised to boil their water for at least a minute before consuming it, although the advisory does say hot water can be used for washing dishes and clothes, and for showering or taking baths.

They say it's a preventive measure.

Meanwhile, the city says it now knows what may have caused the break.

Tetrault explains when they dug the pipe they found that workers made a mistake when installing it fifty years ago. He says  that instead of using sand to cover the top of the concrete, workers poured gravel.                             

"There was a friction between the concrete and the gravel that led to minor cracks, and water got in it, which eventually caused corrosion."

For more information, or to check on the status of the advisory, visit the city of Longueuil's website here.

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