Thousands in Michigan Under Boil Water Advisory

More than 130,000 people in communities north of Detroit are under a boil water advisory after a break in the water main that distributes drinking water to the region from the Lake Huron Water Treatment Facility, the authorities said on Sunday.

The break was discovered early on Saturday morning, according to the Great Lakes Water Authority, and nearly one million Michigan residents were initially instructed to boil water before use as a precaution.

The leak came from a 120-inch water transmission main and was found about one mile west of the water treatment facility in Lake Huron, the authorities said, adding that they expected it would take about two weeks until they could return the pipeline to service.

Water flow and pressure had been restored to many communities as of 11:30 a.m. on Sunday, they said.

But several other communities, including the Village of Almont, Bruce Township, Burtchville Township, Imlay City, Rochester, Shelby Township and Washington Township, were still being instructed to boil water before use. One business in Greenwood and an industrial park in Romeo also remained affected.

On Saturday afternoon, Gov. Gretchen Whitmer of Michigan activated the state’s emergency operations center to respond to the continuing water main break, making state disaster resources available to help communities get necessities like bottled water.

“Our top priority right now is protecting the public health and safety of Michigan residents until this water main is fixed as quickly as possible,” Governor Whitmer said in a statement.

The authorities said that crews had isolated the break and, in preparation for repairs, had begun removing water from the site using pumps. The replacement pipe was already en route to Michigan from Texas, they said.

Barring any unforeseen circumstances, the authorities said that they expected repairs to take a week, and that they would spend the following week testing water quality.

Whenever a water system loses pressure, precautionary measures are recommended, the authorities said, since the loss of pressure can cause bacterial contamination. Boiling the water kills that bacteria.

Under the advisory, residents should not drink tap water without boiling it first, the authorities said. They should boil the water for at least one minute and allow it to cool before using it.

Residents in the affected communities should use boiled, bottled or disinfected water for drinking, making ice, washing dishes, brushing teeth and preparing food “until further notice,” the authorities said, adding that they were investigating the cause of the break.

In a statement released on Sunday morning, Suzanne R. Coffey, the chief executive of the Great Lakes Water Authority, said that the agency understood the “real-life impact” the leak was having on hundreds of thousands of people.

“We truly appreciate their patience and understanding as we work to implement the necessary repairs,” Ms. Coffey said, adding that she was grateful to those “working tirelessly to restore water pressure to all communities.”