(AP) - United Water has issued a boil water advisory for thousands of customers in northern New Jersey.

The advisory was issued early Sunday, shortly after the utility completed a major repair project it had started on Saturday. Workers closed a 30-inch water main, which runs along Route 9W, for several hours to repair one valve and install a new one.

The advisory was issued for customers in Englewood Cliffs, eastern sections of Tenafly and Englewood and northern Fort Lee. They were told to boil their water for one minute before using it for drinking or cooking purposes.

It's not known how long the advisory will remain in effect. United Water officials say they continue to collect water samples in the area and testing is ongoing.