Story highlights Some residents have not been able to use the water in their homes for four days

The mayor says 30 water samples are being tested

(CNN) Many residents of Corpus Christi, Texas, have been told by city officials they will have to wait another 24 hours to see whether they can drinking the city water again.

Mayor Dan McQueen told reporters that 30 water samples have been sent to an Environmental Protection Agency laboratory for testing. The results should be known Sunday.

Water-use restrictions that were imposed Wednesday because of the possible water contamination are still in effect for two of three zones. In the zone where a possible contamination might have taken place, residents have been told not to drink or use water.

In a second zone in the city of 300,000 people, adult residents have been told they can safely bathe and wash clothes. But they should not drink the water or cook with it, the advisory from the Texas Commission on Environmental Quality said. The advisory was lifted in the third zone on Friday.

McQueen said the city three times in December received dirty water reports from a company that officials have not identified. The city investigated each time and determined the problem was not with the water from the city's system.

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