LOUISVILLE, Ky. (WDRB) -- Officials hope a boil water advisory in much of Louisville could be lifted by 8 p.m.  A massive water main break has left about 75,000 people without water.  It affected hospitals, homes, and businesses in a major geographic region of the city.

The boil water advisory was issued Monday evening after the 48-inch line burst near the University of Louisville. The break occurred around 6:20 p.m. and flooded athletic fields on UofL's campus. Firefighters waded through knee deep water to rescue students and children participating in athletic camps.

Humana announced early Tuesday that it is closing its downtown offices for the day.  Other locations will remain open. The University of Louisville closed its Belknap campus canceling classes and closing offices.  The U of L Health Sciences Building and Shelby Campus remained open and on schedule.  All dental patient appointments are also canceled on campus.

Water company officials compared the break to "bursting a vein close to your heart."

Late Monday, it was still unclear what caused the break. Louisville Water Company President Greg Heitzman speculated that the burst happened where two lines form a "T" near Floyd and Eastern Parkway. He said the infrastructure could be "old."

The Louisville Water Company says service is disrupted from downtown to Old Louisville to the Highlands and Audubon Park. In these areas, water is out or water pressure is significantly reduced.

Status of Hospitals:

University Hospital is using pumps to maintain water pressure during the water main break.  But spokesman David McArthur says that has forced some changes in operations.  People are drinking only bottled water, and both employees and visitors are being advised to avoid washing their hands with tap water.  The hospital is setting up clean hand-washing stations and using hand sanitizer.

McArthur says the situation at University is "not normal, but is manageable."

Jewish Hospital says it has water, but is "continuing to abide with the boil water advisories."

WDRB News has also learned that Norton Hospital downtown is being affected, as is Kosair Children's Hospital and Audubon Hospital. A spokesperson for Norton Health Care says Norton's entire downtown medical campus is being affected, but that spokesperson would not elaborate on whether or not the hospitals have any water service. They said patient care is not being affected, and hospital staff are handing out bottled water to patients.

A former employee of WDRB News contacted the station and indicated that the grocery stores near the University of Louisville are out of bottled water.

Employees on Belknap and Medical Center campuses were advised to bring bottled drinking to work on Tuesday, a university spokesman said. 

Kentucky Center:

Air conditioning units at the Kentucky Center for the Performing Arts went down Monday.  That led to the closing of the box office and drive-through counters.  You can still order tickets by calling (502) 584-7777, (800) 775-7777, or (502) 562-0730 TTY, or by going on-line at www.kentuckycenter.org.

Boil water advisory:

WDRB News has also learned that a boil water advisory has been issued for a large part of the Louisville area as a result of the water main break that took place near the University of Louisville.

The boundaries of the boil water advisory are as follows:

Northern Boundary: The Ohio River

Western Boundary: 9th Street

Eastern Boundary: Baxter Avenue and Bardstown Road corner, extending south along Newburg Road

Southern Boundary: The Watterson Expressway

Residents within these boundaries are asked to boil their water before using.

The water company says "Customers in this area should bring all water used for cooking and drinking to a rolling boil for three minutes before consuming (and) discard ice in their ice dispensers.

"Customers outside this boundary who had low pressure during the break should also boil their water."

If you have images of the water main break, please e-mail them to pix@fox41.com. We may run them on the air.

Stay with WDRB.com. We'll have more information as soon as it becomes available.