A boil water advisory warning has been issued for 13 Michigan communities following the discovery of a leak on a water main, according to the Great Lakes Water Authority (GLWA).

The advisory was initially issued for 23 communities on early Saturday morning. But as of 3:00 p.m, the advisory only affects 13 communities after the GLWA took 11 off and added one.

Approximately 288,000 people are affected in the following communities:

Boil water advisories were also advised for one business in Greenwood and one business in Imlay Township, the GLWA stated.

The city of Flint and Flint Township were included in the initial boil water advisory but were removed along with nine other communities, including:

Over 935,000 people were under a boil water advisory at some point on Saturday when all 23 communities were affected, according to ABC News.

The leak was discovered on a 120-inch water transmission main about a mile west of the Lake Huron Water Treatment facility that distributes fresh drinking water to residents in the areas it serves, GLWA stated.

After crews isolate the leak, they will open up emergency connections from other mains to restore uncontaminated water to communities under advisory.

The GLWA noted that there is a chance of bacterial contamination whenever there is a pressure loss in the water system and recommends boiling water to ensure that bacteria or any other organism is killed before use.

Until further notice, it is recommended that affected residents boil water for one minute before “drinking, making ice, washing dishes, brushing teeth, and preparing food.”

Officials are still investigating what caused the initial water transmission leak.

It is unknown how long the advisory will remain.

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