New Jersey American Water customers in several counties are being warned to stock up on bottled water as utility workers could go on strike.

Friday is the deadline for a new contract, and negotiations continued Thursday afternoon. A work stoppage would affect more than a half-million residents, along with thousands of businesses, schools, hospitals, nursing homes and hotels in several counties.

In a full statement, New Jersey American Water said it is in active negotiations with Utility Workers Union Local 423, previously Utility Workers Union Local 391, which services customers in Morris, Warren, Passaic and Essex counties, along with parts of Somerset, Union and Hunterdon counties.

The company said it believes its current offer is "fair and reasonable" and reflects its respect for employees and its commitment to providing quality, reliable service.

New Jersey American Water said its most recent offer followed nine days of bargaining in good faith and multiple separate company proposals each day in an effort to reach an agreement.

The utility also said it has contingency plans in place if union workers do strike and that it expects to continue providing water and wastewater service to the communities it serves.

"American Water says not to worry because they have outside companies and managers ready to operate the system," said Pat Mann, president and chief union negotiator of Local 423 in a statement.

"But who would customers rather have treating and handling their drinking water and responding to emergencies – experienced and highly skilled union workers who undergo stringent background checks? Or unvetted outsiders and a collection of managers with little-to-no experience and years removed from frontline experience? We know who customers would choose."