Corpus Christi, Texas Tells Residents Not to Use Tap Water A "back-flow" incident in the city's industrial district is being blamed.

 -- The city of Corpus Christi, Texas has warned residents not to use tap water after the municipal water supply may have been contaminated by an unknown chemical.

"Late today an unknown chemical substance may have contaminated the City of Corpus Christi drinking water due to a recent back-flow incident in the industrial district," the city said in a statement on Wednesday.

"In an abundance of caution and until results can confirm water safety, the city is issuing an avoid tap water usage until further notice."

Residents were advised to only use bottled water for beverage and food preparation, making ice, brushing teeth, washing dishes or clothes, washing hands, and bathing, "until further notice."

City officials added that water purification treatments, boiling, freezing, filtering, adding chlorine or other disinfectants, or letting the water stand would not make the water safe.

ABC News' Matt Foster contributed to this report.