KEY WEST, Fla. -- The Florida Keys Aqueduct Authority has issued a precautionary boil-drinking-water order to begin Friday and continue through Sunday for most of the Keys, from mile marker 126 through mile marker 6.

The order includes military facilities at Naval Air Station Boca Chica, Sigsbee Park and Truman Annex, but does not include Ocean Reef or the city of Key West, according to FKAA officials.

A break in a 36-inch main freshwater line, discovered Thursday afternoon at the entrance of the aqueduct authority's Florida City-based transmission plant, has necessitated the precautionary boil-water order for human consumption, said FKAA spokeswoman Kathy Ovide.

"We don't have any reason to believe the freshwater supply has been compromised, but need to issue the boil-water order as a precaution," Ovide said.

Ovide said until repairs were completed, water service to all customers in the Keys is being maintained through back pumping and delivery of water from storage tanks.

She said the reason why Key West and Ocean Reef would not be under the precautionary order is because customers there receive their water from storage tanks, which are isolated from the transmission system.