Residents and employees at Lemoore Naval Air Station, about 40 miles south of Fresno, Calif., are being told not to drink the base’s water after more than two dozen people became sick at the base.

Base spokeswoman Melinda Larson says 29 people have become ill with nausea, vomiting and diarrhea.

The source or the cause of what is making people sick has not been determined, but Larson told the Fresno Bee that base residents and base personnel are being told to drink bottled water, not the base’s water.