00:32 Tap Water Warning in Corpus Christi, TX Residents of Corpus Christi, Texas, are warned not to drink city water because of industrial contamination.

At a Glance Corpus Christi, Texas, officials told residents Wednesday to stop drinking or using tap water.

The chemical Indulin AA86, an asphalt emulsifier, was introduced into the city's water supply from a third-party "back-flow incident."

Some 320,000 residents in Corpus Christi, Texas, have been told to not use tap water because it might be contaminated with a petroleum-based chemical.

According to the Associated Press, city officials warned residents in a statement late Wednesday that a "back-flow incident" at an industrial area earlier that day may have caused the chemical to seep into the water. The announcement prompted a rush on bottled water and school closures.

City officials noted in the statement that "boiling, freezing, filtering, adding chlorine or other disinfectants, or letting the water stand will not make the water safe."

"Only bottled water should be used for all drinking, beverage and food preparation (including baby formula and juice), making ice, brushing teeth, washing dishes or clothes, washing hands, and bathing until further notice," the release further states.

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During a press conference Thursday, city officials said about three to 24 gallons of the chemical Indulin AA86, an asphalt emulsifier, seeped into the water supply.

According to a material safety data sheet, Indulin AA86 can cause burning to the skin, eyes or internal organs if ingested . It can also cause an allergic reaction.

City councilman Michael Hunter told the Corpus Christi Caller-Times that the city issued the warning in order to "take every precaution that we can to make sure that everybody is safe," adding that it's unlikely the chemicals infecting the city's supply are concentrated enough to do harm.

Lillian Riojas, a spokeswoman for Valero, issued a statement saying the backflow issue occurred near Valero's asphalt terminal and was prompted by Valero's Corpus Christi refineries.

"At this time, we believe this is a localized backflow issue from third party operations in the area of Valero’s asphalt terminal. We do not believe this issue is being caused by Valero’s Corpus Christi refineries. While the City continues to investigate this issue, we do not believe the City’s water has been impacted," the statement reads. "We believe this issue is isolated to a lateral industrial line. Valero is offering its resources to assist the City in isolating the issue and to help confirm this has not impacted the City’s water supply."

The announcement prompted school and business closures on Thursday and triggered long lines at grocery stores as people stocked up on bottled water.

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