About 9,000 St. Lucie County Utilities customers on North Hutchinson Island face a boil water order.
A water main break has interrupted service.
The utility says it was caused by a contractor error.
Once service is back the boil order will be in place.
Water used for drinking or cooking will need to be boiled.
Experts say a rolling boil of one minute is sufficient.
Customers can also use bottled water.
Anyone with questions can call St. Lucie County Utilities at 772-462-1150.