A cross-contamination incident caused water fountains and concessions at the terminal to close down on Wednesday.
Airport authorities believe the problem was related to work on the airport's central utility plant, where recycled air conditioning water contaminated a water line.
LAX says the staff immediately notified all airlines and concessionaries of the contamination and notified the public not to drink the water. Restrooms remained open with portable hand washing sinks.
The airport handed out food, bottled water and snacks to passengers and workers during the duration of the incident.
The water was declared safe early Thursday morning after the terminal's water lines were flushed and the water tested.