Many are without water or have low pressure after a main ruptured near the University of Louisville campus. A boil-water advisory is in effect for Kentucky's largest city.
The 48-inch main broke Monday evening.
A Louisville Water Co. spokesman says crews are trying to isolate the break and repair it. He says about 75,000 people have no water or low pressure.
The company issued a boil-water advisory for customers in large area. Anyone outside the boundary who had low pressure during the break should also boil their water.
The rupture flooded an area about the size of a city block by the university.