DAYTON, Ohio (AP) — The city of Dayton, Ohio, is telling residents their water is OK to use again without being boiled first.

City authorities said late Friday morning that water samples were clear of bacteria. However, some 15,000 to 20,000 customers elsewhere in Montgomery County remained under a boil-water advisory. A household or business is counted as one customer.

Crews located a water-line leak Thursday under the Great Miami River, but high river levels have hindered repair work. There’s been no word on the break’s cause.

Schools resumed Friday, a day after many closed. The Dayton school district says bottled water is available in all buildings.

Dayton officials estimated 75,000 people — more than half the city’s population — began Friday under the boil-water advisory.